EPA-450/2-77-022 


November 1977 

(OAQPS NO. 1.2-079) 

OAQPS GUIDELINES 

CONTROL OF VOLATILE 

ORGANIC EMISSIONS 

FROM 

SOLVENT METAL CLEANING 

I U.S. ENVIRONMENTAL PROTECTION AGENCY 

Office of Air and Waste Management 1 

Office of Air Quality Planning and Standards a0- I,\ Research Triangle Park, North Carolina 2771 1

328 1 

RADIAN LIBRARY
 I, DURHAM, N.C. 


II i. 
This report is issued by the Environmental Protection Agency to report 

technical data of interest to a limited number of readers. Copies are 

available free of charge to Federal employees, current contractors anc! 

grantees, and nonprofit organizations - in limited quantities - from the 

Library Services Office (MD-35). Research Triangle Park, North Carolina 

27711; or, for a fee, from the National Technical Information Service, 

5285 Port Royal Road, Springfield, Virginia 22161. 

Publ ication No. EPA-45012-77-022 
PREFACE 


The purpose of this document is to inform regional, State, and local 

air pol 1 ution control agencies of the different techniques available for 

reducing organic emissions from solvent metal cleaning (degreasing) . Solvent 

metal cleaning includes the use of equipment from any of three broad categories: 

cold cleaners , open top vapor degreasers , and conveyori zed degreasers. A1 1 

of these employ organic solvents to remove soluble impurities from metal 

surfaces. 

The diversity in designs and applications of degreasers make an emission 

1imi t approach inappropriate; rather, regulations based on equipment specifications 

and operating requirements are recomnended. Reasonably available control 

technology (RACT) for these sources entails implementation of operating 

procedures which minimize solvent bss and retrofit of applicable control devices. 

Required control equipment can be as simple as a manual cover or as complex 

as a carbon adsorption system, depending on the size and design of the 

degreaser. Required operating procedures include covering degreasing 

equipment whenever possible, properly using solvent sprays, reducing the amount 

of solvent carried out of the unit on cleaned work by various means, promptly 

repairing leaking equipment, and most importantly properly disposing of wastes 

containing volatile organics. Not all controls and procedures will be applicable 

to a1 1 degreasers, a1 though in general specific operating requirements and 

control devices will be applicable to the majority of designs within each 

category of degreasers. Control of open top and conveyorized vapor 

degreasing is the most cost effective, followed by waste solvent disposal 

for a11 degreasing operations, manufacturing cold cleaning and maintenance 

cold cleaning. 

iii 
swi tches are : 

1. Vapor level control thermostat, 

2. Condenser water flow switch and thermostat, 

3. Sump thermostat, 

4. Solvent level control, 

5. Spray safety switch. 

The first four safety switches 1isted above turn off the sump heat while the 

fifth turns off the spray. 

The most important safety switch is the vapor level control thermostat. 

This device is activated when solvent vapor zone rises above the designed 

operating level. This can occur if the coolant flow is interrupted, for 

example. When the hot vapors are sensed, the sump heater is turned off thus 

minimizing vapor escape. This thermostat should be a manual reset type for 

manually operated degreasers. For conveyorized degreasers, the vapor level 

control thermostat should activate an alarm system. These controls should 

be checked frequently. 

The condenser water flow switch and thermostat turn off the sump heat 

when either the condenser water stops circulating or the condenser water becomes 

warmer than specified. If the condenser water flow swi tch and thermos tat is 

properly adjusted, then it will serve as a back-up for the safety vapor 

thermostat and also assure efficient operation of the condenser coils. 

In summer months, the cooling water for condensing coils often becomes too 

warm. In this case, the thermostats in a condenser water flow switch can 

signal a need for improvement, such as increasing the water flow rate. This 

problem occurred during a test performed for EPA. 16 

As oils, greases and other contaminants build up in the solvent, the 

boiling point of the mixture increases. Both the sump thermostat and solvent 

3-1 5 

TABLE 1. CONTROL SYSTEMS FOR COLD CLEANING 

Control System A 

Control Equipment: 

1. Cover 

2. Facility for draining cleaned parts 

3. Permanent, conspicuous label. sumnarizing the operating requirements 

Operating Requirements: 

1. Do not dispose of waste solvent or transfer it to another ~arty, 

such that greater than 20 percent of the waste (by weight) can evaporate 

into the atmosohere.* Store waste. solvent on1 v in covered containers. 

2. Close degreaser cover whenever not handling parts in the cleaner. 

3. Orain cleaned parts for at least 15 seconds or until dripping ceases. 

Control System B 

Control Equipment: 

1. Cover: Same as In System A, except if (a) solvent volatility is 

reater than 2 kPa (15 mn Hg or 0.3 psi) measured at 3B°C (10O0F),** 9b) solvent is agitated. or (c) solvent is heated, then the cover must 

be designed so that i: can be easily operated with one hand. (Covers for 

larger degreasers may require mechanical assistance, by spring loading, 

cdunterweiqhtinq or Dowered svsterns.) 

2. Drainage facility: Same as in System A, except that if solvent 

volatility is greater than about 4.3 kPa (32 mn Hg or 0.6 psi) veasured at 

38°C (lOO°F), then the drainage facility nust be internal. so that oarts are 

enclosed under the cover while draining. The drainage facility may be 

external for applications where an internal type cannot fit into the cleaning 

system. 

3. Label : Same as in System A 

4. If used, the solvent spray must be a solid, fluid stream (not a 

fine, atomized or shower type spray) and at a pressure which does not cause 

excessive splashing. 

5. Major control device for highly volatile solvents: If the solvent 

volatility is D 4.3 kPa (33 n Hg or 0.6 psi) measured at 38°C (lOO°F), or 

if solvent is heated above 50'C (12O0FJ, then one of the following control 

devices must be used: 

a. Freeboard that gives a freeboard ratiow* 20.7 

6. Nater cover (solvent must be insoluble in and heavier than water) 

c. Other system of equivalent control, such as a refrigerated chiller 

or carbon adsorption. 

Operating R~rprirrn~ntq: 

Sawe as in System P 

*Water and solid waste regulations must also be comolied with. 

**Senerally solvents consisting primarily gf mineral :pirits [:?oddard) have 

tolatilities < 2 CPa. 

***Freeboard ratio is defined aj the freoocard Aeignt divided by the 

uidth of the degreaser. 
Two levels of control for each type of degreaser have been identified 

here as examples of reasonably avai 1 able control technology (RACT). In general, 

control level A shows proper operating practice and simple, inexpensive 

control equipment. Control level B consists of level A plus additional 

requi rements to improve the effectiveness of control. The degree of 

emission reduction for both individual items and control levels are 

discussed in the text. Specific requirements can be modified to achieve 

whatever level of control is necessary. Control systems for cold cleaners 

are shown in Table 1, thosefbr open top vapor degreasers in Table 2, and 

those for conveyorized degreasers in Table 3. 

Two exemptions are recommended. First, conveyorized degreasers smaller 

2
 than 2.0 m of air/vapor interface should be exempt from a requirement for 

a major control device. This would not be cost effective and would tend to 

move the small conveyorized degreaser users to open top vapor degreasers 

which emit more solvent per unit work load. Second, open top vapor degreasers 

2 smal ler than 1 m of open area should be exempt from the application of 

refrigerated chi 1 lers or carbon adsorbers. Again, requi rement for these 

would not be cost effective. 
TABLE 3. CONTROL SYSTEMS FOR CONVEYORIZED DEGREASERS 

Control System A 

Control Equipment: None 

Operating Requirements : 

3 2 1. Exhaust ventilation should not exceed 20 m /min per m (65 cfm per ft2) 

of degreaser opening, unless necessary to meet OSHA requirements. Work place 

fans should not be used near the degreaser opening. 

2. Minimize carry-out emissions by: 

a. Racking parts for best drainage. 

b. Maintaining verticle conveyor speed at < 3.3 m/min (11 ft/min) 

3. Do not dispose of waste solvent or transfer it to another party such 

that greater than 20 percent of the waste (by weight) can evaporate 

into the atmosphere. Store waste solvent only in covered containers. 

4. Repair solvent leaks imnediately, or shutdown the degreaser. 

5. Water should not be visibly detectable in the solvent exiting the 

nater separator. 

Control System B 

Control Equipment : 

1. Major control devices; the degreaser must be controlled by either: 

a, Refrigerated chiller, 

b. Carbon adsorption system, with ventilation L 15 m2/min per m 2 (50 cfm/ft 2) 

of air/vapor area (when down-time covers are open), and exhausting <25 ppm of 

solvent by volume averaged over a complete adsorption cycle, or 

c. System demonstrated to have control efficiency ?quivalent to or better 

than either of the above. 

2. Either a drying tunnel, or another means such as rotating (tumbling) 

basket, sufficient to prevent cleaned parts from carrying out solvent liquid 

or vapor. 

3. Safety switches 

a. Condenser flow switch and thermostat - (shuts off sump heat if 

coolant is either not circulating or too wan). 

b. Spray safety switch - (shuts off spray pump or conveyor if the vapor 

level drops excessively, e.g. > 10 cm (4 in.)). 

c. Vapor level control thermostat - (shuts off sump heat when vapor 

level rises too high). 

4. Minimized openings: Entrances and exits should silhouette work 

loads so that the average clearance (between parts and the ed~e of the 

degreaser opening) is either <10 cm (4 in.) or <I0 percent of the width 

of the opening. 

5. Down-time covers: Covers should be provided for closing off the 

entrance and exit during shutdown hours. 

Operating Requirements: 

1. to 5. Same as for System A 

6. Down-time cover must be placed over entrances and exits of conveyorized 

degreasers immediately after the conveyor and exhaust are shutdown 

and removed just before they are started up. 
- - 

TABLE 2. COMPLETE CONTROL SYSTEMS FOR OPEN TOP VAPOR DEGREASERS 

Control System A 

Contrcl Equi went: 

1. Cover that can be opened and closed easily without disturbing the 

vapor zone. 

Operating Requirements: 

1. Keep cover closed at all times except when processing work loads 

through the degreaser. 

2. Minimize solvent carry-out by the following measures: 

a. Rack parts to allow full drainage. 

b. Move parts in and out of the degreaser at less than 3.3 m/sec (11 ft/min). 

c. Degrease the work load in the vapor zone at least 30 sec. or until 

condensation ceases. 

d. Tip out any pools of solvent on the cleaned parts before removal. 

e. Allow parts to dry within the degreaser for at least 15 sec. or until

visually dry. 

3. Do not degrease porous or absorbent materials, such as cloth, leather, 

wood or rope. 

4. Work loads should not occupy more than half of the degreaser's open 

top area. 

5. The vapor level should not drop more than 10 cm (4 in) when the 

mrk load enters the vapor zone. 

6. Never spray above the vapor level 

7. Repair solvent leaks imnediately, or shutdown the degreaser. 

8. Do not dispose of waste solvent or transfer it to another party 

such that greater than 20 percent of the waste (by weight) will 

evaporate into the atmosphere. Store waste solvent only in closed containers. 

9. Exhaust ventilation should not exceed 20 m3/min per m2 (65 cfm per ft2) 

of degreaser open area, unless necessary to meet OSHA requirements. Ventilation 

fans should not be used near the degreaser opening. 

10. Water should not be visually detectable in solvent exiting the water 

separator. 

Contro: System B 

Control Equipment: 

1. Cover (same as in system A). 

2. Safety switches 

a. Condenser flow switch ana tkrmostat - (siurts off sump neat if condenser 

coolant is either not circulating or too ram). 

b. Spray safety switch - (shuts off spray pump if the vapor level drops 

excessively. about 10 cm (4 in). 

3. Major Control Device: 

Either: a. Freeboar9 ratio reater than or equal to 0.75, and if the 

degreaser opening is > 1 m (10 ftB ), the cover must be powered, 

b. Refrigerated chiller, 

c. Enclosed design (cover or door opens only when the dry part 

is actually entering or exiting the degreaser.) , d. Carbon adsorption system, with ventilation 2 15 m3/min per m 2 

(50 cfm/ft ) of air/vapor area (when cover is open), and exhausting <25 ppm 

solvent averaged over one complete adsorption cycle, or 

e. Control svstem. demonstrated to have control efficiency, 

equivalent to or better than any Of the above. 

4. Permanent, conspicuous label. sumnarizing operating procedures #1 to #6. 

Operating Requirements : 

Same as in System A 
Page 

............ 3.1 .1.3 Refrigerated Chi 11 ers 3-6


............. 3.1 .1.4 Carbon Adsorption 3-9


3.1.1.5 SafetySwitches ............... 3.14 


3.1.2' Controls to Miniinize Carry-Out ............ 3-16 


3.1.3 Controls for Both Solvent Bath and 

Carry-Out Emi.ssions Com6ined ............ 3-18 


3.1.3.1 
 Automated Cover-Conveyor System ....... 3-18 


3.1.3.2 
 Refrigeration Condensation ......... 3-20 


3.1.4 Control 
of Haste Solvent Evaporation ......... 3-22 


3.1.4.1 
 Cuwent Practices .............. 3-22 


3.1.4.2 
 Recommended Practices ............ 3-23 


3.1.5 Other Control Dey'i'ces ................ 3-27 


3.1.5.1 Incineration ................ 3-28 


3.1.5.2 Liqufd Absorption .............. 3-28 


3.2 Complete Control Systems .................. 3-29 


3.2.1 Cold Cleaning Control Systems ............ 3-30 


3.2.2 Control Systems for Open Top Vapor 

Degreasing ...................... 3-32 


3.2.3 Control Systems for Conveyorized Degreasers ..... 3-32 


3.3 References ......................... 3-37 


Chapter 4.0 Cost Analysis ........................ 4-1 


4.1 Introduction ........................ 4-1 


4.1.1 Purpose ....................... 4-1 


4.1.2 Scope ........................ 4-1 


4.1.3 Model Plants ..................... 4-2 


4.1.4 Capital Cost Estimates ................ 4-3 

TABLE OF CONTENTS 

Page 

Preface ................................. iii 


Chapter 1.0 Introduction and Summary .................. 1-1 


1.1 rieed to Regulate Solvent Metal Cleaning .......... 1-1 


1.2 Regulatory Approach .................... 1-2 


Chapter 2.0 Sources and Types of Emissions ............... 2-1 


2.1 Industry Description .................... 2-1 


2.2 Types of Degreasers and Their Emissions .......... 2-4 


2.2.1 Cold Cleaners .................... 2-7 


2.2.1.1 Design and Operation ............ 2-7 


2.2.1.2 Emissions ................. 2-12 


2.2.2 Open Top Vapor Degreasers .............. 2-16 


2.2.2.1 Design and Operation ............ 2-16 


2.2.2.2 Emissions ................. 2-25 


2.2.3 Conveyorized Degreasing ............... 2-33 


2.2.3.1 Design and Operation ............ 2-33 


2.2.3.2 Emissions ................. 2-39 


2.4 References ........................ 2-45 


Chapter 3.0 Emission Control Techno1 ogy ................ 3-1 


3.1 Emission Control Devices ................. 3-1 


3.1.1 Emission Control Devices .............. 3-1 


3.1 1 Improved Cover ............... 3-2 


3.1.1.2 High Freeboard ............... 3-5 

Page 

6.1 Observation of Control Eqo~Qment and 

Operating Practices .................... 6-2 


6.2 Material Balance ..................... 6-2 


6.3 Other Emission Tests ................... 6-3 


Chapter 7.0 Enforcement Aspects .................... 7-1 


7.1 Regulatory Approaches ................... 7-2 


7.1.1 Emission Standards ................. 7-2 


7.1.2 Equipment Standards ................ 7-3 


7.1 .3 Operational Standards ............... 7-4 


7.1.4 Sol vent Exemptl'on Standards ............ 7-5 


7.2 Affected Facilities .Pri'oriities ............. 5 


7.2.1 Definitions of Affected Facilities ......... 7-5 


7.2.2 Priorities of Enforcement ............. 7-5 


Appendix A.0 Emission Test Results 

Appendix 0.0 Calculationr 
Page 

4.2 Cold Cleaners ........................ 4-4 


4.2.1 Model Plant Parameters ................ 4-4 


4.2.2 Control Costs .................... 4.0 


4.3 Open Top Vapor Degreasers .................. 4-8 


4.3.1 Model Plant Parameters ................ 4-8 


4.3.2 Control Costs .................... 4-8 


4.3.3 Cost Effectiveness .................. 4-14 


4.4 Conveyorized Degreasers ................... 4-16 


4.4.1 Model Plant Parameters ................ 4-10 


4.4.2 Control Costs .................... 4-18 


4.4.3 Cost Effectiveness .................. 4-20 


4.5 References ......................... 4.24 


Chapter 5.0 Adverse Environmental Effects of Appl yfng 

The Technology ........................ 5-1 


5.1 AirImpacts ......................... 5-1 


5.2 Uater Impacts ........................ 5.1 


5.2.1 Waste Solvent Disposal ................ 5-1 


5.2.2 Steam Condensate from Carbon Adsorpti'on ....... 5-2 


5.2.2.1 Chlorinated Solvent ih Steam 

Condensate ................. 5-2 


5.2.2.2 Stabilizers in Steam Condensate ....... 5-3 


5.2.3 Effluents from Water Separators ........... 5-4 


5.3 Solid Waste Impact ..................... 5-4 


5.4 Energy Impact ........................ 5-5 


5.5 Other Environmental Concerns ................ 5-6 


5.6 References ......................... 5-8 


Chapter 6.0 Compliance Testing Methods and Moni'tori'ng 

Techniques ......................... 6-1 

Figure 2-1 
 Cold Cleaner ........................ 2-9 


Figure 2-2 
 Cold Cleaner Emission Poi.nts ................ 2-13 


Figure 2-3 
 Open Top Vapor Degreaser .................. 2-18 


Figure 2-4 
 Basic Principle for Uater Separator for Yapor Degreaser . . 2-20 

Figure 2-5 
 Open Top Degreaser with Offset Condenser Coils ....... 2-21 


Figure 2-6 
 Two Compartment Degreaser with Offset Boili'ng Chamber ... 2-22 

Figure 2-7 
 Two Compartment Degreaser ................. 2-23 


Figure 2-8 
 Degreaser with Lip Exhaust ................. 2-24 


Figure 2-9 
 Open Top Vapor Degreaser Emission Points .......... 2-26 


LIST OF FI'GURES 

Page 

Figure 2-10 Cross Rod Conveyorized Degrearer .............. 2-35 


Figure 2-11 Monorail ConveyorPzed Degreaser .............. 2-36 


Figure 2-12 Vibra Degreaser ...................... 2-37 


Figure 2-13 Ferris Uheel Degreas.er ................... 2-38 


Figure 2-14 
Mesh Belt Conveyorized Degreaser .............. 2-40 


Figure 2-15 
 Conveyorized Degreaser Emission Points ........... 2-42 


Figure 3-1 
 Refrigerated Freeboard Chiller ............... 3-7 


Figure 3-2 
 Carbon Adsorber ...................... 3-10 


Figure 3-3 
 Adsorption Cycle ...................... 3-11 


Figure 3-4 
 Desorption Cycle ...................... 3-12 


Figure 3-5 
 Elevator Design of Degreaser .Vapor Type ......... 3-19 


Figure 3-6 
 Vapor Pressures of Several Sol~ents ............ 3-21 


Figure 3-7 
 External Still ....................... 3-25 


Figure 4-1 Cost-Effectivenass of A1 ternat ive Control Opti'ons for 

Existing Open Top Vapor Degreasers ............. 4-15 


Figure 4-2 Cost-Effectiveness of Alternative Control Options for 

Existing Monorail Degreasers ................ 4-21 


Figure 4-3 Cost-Effectiveness of Alternative Control Optfons for 

Existing Cross-Rod Degreasers ............... 4-23 


xiii 
LIST OF TABLES 

Page 

.............. Table 1 Control Systems for Cold Cleaning v


Table 2 Control Systems for Open Top Vapor Degreasers ........ vi 


Table 3 Control Systems for Conveyorized Degreasers ......... vi i 


Table 2-1 Common Metal Cleaning Solvents ................ 2-3 


Table 2-2 National Degreasing Solvent Consumption (1974) ........ 2-5 


Table 2-3 Emissions from Sol vent Degreasers (1 974) ........... 2-6 


Table 3-1 Control Systems for Cold Cleaning .............. 3-31 


Table 3-2 Complete Control Systems for Open Top Vapor Degreasers .... 3-33 


Table 3-3 Control Systems for Conveyorized Degreasers ......... 3-35 


Table 4-1 Cost Parameters for Model Cold Cleaners ........... 4-5 


Table 4-2 Control Costs for Typical Cold Cleaners ........... 4-7 


Table 4-3 Cost Parameters for Model Open Top Yapor Degreasers ..... 4-9 


Table 4-4 Control Cost for Typi'cal Stze Open Top Vapor Degreaser .... 4-10 


Table 4-5 Control Cost for Small Open Top Vapor Degreaser ....... 4-11 


Table 4-6 Cost Parameters for Model Conveyorized Degreasers ...... 4-17 


Table 4-7 Control Costs for Typical Con~eyorized Degreasers ...... 4-19 

1,0 INTRODUCTION AND SUMMARY 

The purpose of EPA's series of control technique guideline documents 

is to provide guidance on emission reduction techniques which can be applied 

to existing sources in specific industries. The documents are to be used to 

assist States in revising their implementation plans (SIP'S) to attain and 

maihtain National Ambient Air Qua1ity Standards (NAAQS) . This document discusses 

vol ati 1 e organi c compound (VOC) emissions and appl icable control techniques 

for organic sol vent metal cleaning operations (degreasing with sol vents). 

1.1 NEED TO REGULATE SOLVENT METAL CLEANING 

Solvent metal cleaning is a significant source of volatile organic 

compounds (VOC) and tends to be concentrated in urban areas where the 

oxidant NAAQS is 1 ikely to be exceeded. In 1975 solvent metal cleaning 

emitted about 725 thousand metric tons of organics. This represents 

about four percent of the national organic emissions from stationary 

sources. Presently, solvent metal cleaning is the fifth largest stationary 

source of organic emissions. Although emissions from solvent degreasing 

(i .e. , metal cleaning) represent about four percent of nationwide VOC 

sources, the proportion is significantly higher in most urban areas, 

because of their high concentration of metalworking industries. For example, 

to upper atmospheric ozone depletion. These reasons and others support the 

decision to concentrate on positive reduction rather than subs ti tution. 

Positive emission reduction from sol vent metal cleaning shoul d be 

attained t+ugh use of proper operating practices and retrofit control 

equipment. Proper operating practices are those which minimize solvent 

loss to the atmosphere. These include covering degreasing equipment 

whenever possible, proper use of solvent sprays, various means of reducing 

the amount of solvent carried out of the degreaser on cleaned work, prompt 

repair of leaking equipment, and most importantly, proper disposal of wastes 

containing volatile organic sol vents. In addition to proper operating 

practices there are many control devices which can be r e t r o f i t t o degreasers; 

however, because of the diversity in their designs, not all degreasers 

require a1 1 control devices. Small degreasers using room temperature sol vent 

may require only a cover, whereas a large degreaser using boiling solvent 

may require a refrigerated freeboard chiller or a carbon adsorption system. 

Two types of control equipment which will be applicable to many degreaser 

designs are drainage facilities for cleaned parts and safety switches and 

thermostats which prevent 1arge emissions due to equipment ma1 functi on. The 

many degreaser designs along with the emissions characteristic of those 

designs and the factors affecting those emissions are described in Chapter 2. 

Control devices for each type of emission and control systems for each 

degreaser design are described in Chapter 3. 
the Southern California Air Quality Management District estimates that 14.8 

percent of the stationary organic emissions in Los Angeles County are 

attributable to sol vent degreasi ng. 

Control technology is available to reduce hydrocarbon emissions from 

existing sol vent metal cleaning operations. However, this techno1 ogy has 

not been broadly applied 1 argely because of unawareness of economic 

incentives and the absence of regulatory requirements. In 1974, for example, 

16 states covered degreasing operations with solvent regulations identical 

or similar to Rule 66 of the Los Angeles County Air Pol lution Control District. 

Since then, additional state and local agencies have adopted the same types of 

statutes. Generally, up to 3,00 0 pounds of VOC emissions per day are allowed 

from sources using sol vents consi dered non-photochemi cal ly reacti ve under 

Rule 66 criteria. Since solvent metal cleaning operations rarely release 

more than that amount, they have usually complied with Rule 66 regulations 

merely by substitution. Regulatory incentive to institute control technology 

rather than substitution is necessary to achieve positive emission reduction. 

1.2 REGULATORY APPROACH 

Photochemical oxidant control strategies in the past have re1 ied heavily 

on the substitution of solvents of re1 atively low photochemical reactivity to reduce 

emissions of higher reactivity VOC. Thus, total emissions did not necessari ly 

decrease, only the make-up of those emissions changed. One problem with this 

approach was that many solvents classed as low reactivity materials have since 

been found to be moderately and in some cases highly reactive. EPA's current 

direction and the direction of this document is toward positive reductions of 

all VOC emissions. This is not only more rational from a standpoint of 

conservation but some low reactivity solvents are now suspected of contributing 
2.0 SOURCES AND TYPES OF EMISSIONS 

2.1 INDUSTRY DESCRIPTION 

Sol vent metal cleaning describes those processes using non-aqueous 

solvents to clean and remove soils from metal surfaces. These solvents, 

which are principally derived from petroleum, include petroleum distil 1ates, 

chlorinated hydrocarbons, ketones, and a1 coho1 s . Organic sol vents such as 

these can be used alone or in blends to remove water insoluble soils for 

cleaning purposes and to prepare parts for painting, plating, repair, 

inspection, assembly, heat treatment or machining. 

Sol vent metal cleaning is usually chosen after experience has indicated 

that sati sfactory cleaning is not obtained with water or detergent solutions. 

Availability, low cost and farni: iari1.y combine to make water the first 

consideration for cleaning; however, water has several 1 imitations as a 

cleaning agent. For example, it exhibits low solubility for many organic 

soils, a slow drying rate, electrical conductivity, a high surface tension 

and a propensity for rusting ferrous metals and staining non-ferrous metals. 

All of these limitations can be overcome with the use of organic solvents. 

A typical industrial degreasing solvent would be expected to dissolve 

oils, greases, waxes, tars, and in some cases water. Insoluble matter such 

as sand, metal chips, buffing abrasives or fibers, held by the soils, are 

flus hed away. 
Table 2-1 

COmN METAL (3LEANING SOLVENTS  

Type of Solvent/ 

Solvent 

Alcohols 

Ethanol (958) 

Isopropanol 

Methanol 

Aliphatic Hydrocarbons 

Heptane 

Kerosene 

S toddard 

Mineral Spirits 66 

Aromatic Hydrocarbons 

Benzenea**  

SC 150 N 

I Toluene w Turpentine 

Xy lene 

Chlorinated Solvents 

Carbon Tetrachloride*** 

Methylene Chloride 

Perchloroethylene 

1,1,l-Trichloroethans 

Trichloroethylene 

Fluorinated Solvents 

Trichlorotrifluoroethane (PC-113) 

Ketones 

Acetone 

Methyl ethyl ketone 

Solvency for 

Metal Working 

- Soils 

Poor 

poor 

poor 

good 

good 

good 

good 

good 

good 

good 

good 

good 

excellent 

excellent 

excellent 

excellent 

excel lent 

*Federal Register, June 27, 1974, Vol. 39, No. 125. 

Toxicity 

(PP~ 

lOOO* 

400* 

200* 

500* 

500 

200 

200 

lo* 

200 

200' 

loo* 

loo* 

lo* 

500' 

loo* 

350* 

loo* 

lOOO* 

lOOO* 

200* 

Flash 

- Point 

60°F 

55°F 

58°F 

<20°F 

149°F 

105°F 

107°F 

10°F 

151°F 

4 5°F 

91°F 

81°F 

none 

none 

none 

none 

none 

none 

<OOP 

28°F 

Water 

Evaporation Solubility Boiling Point 

Ra te* (8 wt.) (Range) 

Pounds 

Per Gal. 

6.76 

6.55 

6.60 

5.79 

6.74 

6.38 

6.40 

7.36 

7.42 

7.26 

7-17 

7.23 

13.22 

10.98 

13.47 

10.97 

12.14 

13.16 

6.59 

6.71 

Price 

Per Gal. 

$ 1.59 

$ 1.26 

S 1.11 

$ 0.86 

$ 0.66 

$ 0.62 

$ 0.62 

- - 

S 1.06 

$ 0.90 

S 2.40 

$ 0.96 

$ 3.70 

$ 2.83 

$ 3.33 

$ 2.7a 

S 3.13 

S 7.84 

S 1.45 

$ 1.74 

**~va~oratioi ate-determined by weight 106s of 50 mls in a 125 ml beaker on an analytical balance (Dow Chemical Co. method). 

***Not recommended or sold for metal cleaning (formerly standards in industry). 

****Primary source from The Solvents and Chemicals Companies 'Physical Properties of Comn Organic Solvents' and Price List 

(July 1, 1975). 
A broad spectrum of organic solvents is available. Choices among the 

solvents are based on the solubility of the soil, toxicity, flammability, 

evaporation rate, effect on non-rtietallic portions of the part cleaned and 

numerous other properties. The r~ost important properties of sol vents 

commonly used in metal cleaning are summarized in Table 2-1. 

As would be expected, the metal working industry is the major user of 

solvent metal cleaning. Eight SIC codes (Numbers 25 and 33 to 39) cover 

these industry categories. Examples of industries within these cjassifications 

are automotive, electronics, appliances, furniture, jewelry, plumbing, 

aircraft, refrigeration, business machinery and fasteners. A1 1 are frequent 

users of organic solvents for metal cleaning. However, the use of solvents 

for metal cleaning is not limited to these industries; solvent metal cleaning 

is also used in non-metal working industries such as printing, chemicals, 

plastics, rubber, textiles, glass, paper and electric power. Often, the 

function of the organic solvents in these industries is to provide maintenance 

cleaning of electric motors, fork lift trucks, printing presses, etc. Even in 

non-manufacturing industries, solvent metal cleaning is commonplace. Most 

autornoti ve, rai 1 road, bus, aircraft, truck and electric tool repai r stations 

use these solvents. In short, most businesses perform solvent metal cleaning, 

at least part time, if not regularly. The number of companies routinely using 

solvent metal cleaning operations probably exceeds one million. Furthermore, 

large scale users may often have over 100 separate degreasing operations at 

one plant location. 

Solvent metal cleaning is broken into three major categories: cold 

cleaning, open top vapor degreasi ng and conveyorized degreasi ng . In col d 

cleaning operations, all types of solvents are used depending on the type 

of parts to be cleaned. Vapor degreasing uses halogenated solvents because 
- - 

Table 2-2 

National Degreasing Sol vent Consumption* (1974) 

Sol vent Consumption (10' metric tons) 

So 1 vent Type Cold cleaning Vapor degreasing All degreasing 

Halogenated: 

Trichl oroethylene 25 128 153 

1,1,1 Trichloroethane 82 80 162 

Perchloroethyl ene 13 41 54 

Methylene Chloride 23 7 30 

Tri chl orotri fl uoroethane 10 20 30 

153 276 429 

A1iphatics 222 222 

Aromatics : 

Benzene 

To1 uene 

Xyl ene 

Cycl ohexane 

Heavy Aroma tics 

Oxygenated: 

Ketones : 

Acetone 10 

Methyl Ethyl Ketone 8 

Butyl 5 

Ethers 6 

*3 

Total Sol vents : 450 276+** 726 

Range of Accuracy: (+125) (95 (+I45) 

*See Appendix B.l for background on the above estimates. ** 

Includes 25,000 metric tone~frorn non boi 1 ing convevorized degreasers. *** 

Iqcl udes 75,000 netri c tons from conveyorized vapor degreasers. 
they are not flammable and their vapors are much heavier than air. 

The most recent estimates are that there are 1,300,000 cold 

cleaning units in the United States, with about 70 percent of these 

devoted to maintenance or servicing operations and the remainder used 

for manufacturing operations. There are a1 so an estimated 22,000 open 

top vapor degreasers and 4,000 conveyorized degreasers. Of the estimated 

726,000 metric tons per year of solvent used for degreasing, roughly 60 

percent is for cold cleaning, 25 percent for open top vapor degreasing 

and 15 percent for conveyorized degreasing. Tables 2-2 and 2-3 summarize 

the above information. Emissions are discussed in detail in the next 

chapter. 

2.2 TYPES OF DEGREASERS AND THEIR EMISSIONS 

There are three basic types of organic solvent degreasers: cold 

cleaners, open top vapor degreasers, and conveyori zed degreasers. Col d 

cleaners are usually the simplest and least expensive. Their solvent is 

usually near room temperature, but is sometimes heated. The temperature, 

however, always remains below the solvent's boiling point. A cold cleaner 

is a tank of solvent usually including a cover for nonuse periods. Inside 

is a work surface or basket suspended over the solvent. An open top vapor 

degreaser resembles a large cold cleaner; however, the solvent is heated to 

its boiling point. This creates a zone of solvent vapor that is contained by 

a set of cooling coils. Both the cold cleaner and the open top vapor degreaser 

clean individual batches of parts; thus, they are termed "batch loaded". A 

conveyori zed degreaser is 1oaded continuously by means of various types of conveyor 

systems, and may either operate as a vapor degreaser as a cold cleaner. 
2.2.1 Cold Cleaners 

Cold cleaner operati ons include spraying , brus hi ng , f 1 us hi ng and 

imnersion. The solvent occasionally is heated in cold cleaners but always 

remains we11 below its boiling point. 

Cold cleaners are defined here not to include nonboiling conveyorized 

degreasers which are covered in Section 2.3. Wipe cleaning is also not 

included. 

Cold cleaners are estimated to result in the largest total emission 

of the three categories of degreasers. This is primarily because of the 

extremely large number of these units (over 1 million nationally) and because 

much of the disposed of waste solvent is allowed to evaporate. It is 

estimated that cold cleaners emit 380 thousand metric tons of organics per 

year, this being about 55 percent of the national degreasing emissions 

(see Appendix B. 1). Cold cleaning solvents nationally account for almost 

all of the aliphatic, aromatic, and oxygenated degreasing solvents and 

about one-third of halogenated degreasing solvents. 

Despite the large aggregate emission, the average cold cleaning unit 

generally emits only about one-third ton per year of organics, with about 

one-half to three-fourths of that emission resulting from evaporation of 

the waste solvent at a disposal site. 

2.2.1.1 Design and Operation -
Table 2-3 

Emissions from Solvent Degreasers (1974) 

Estimated National Approximate Averaged Emission 

Emi ssi on No. of Uni t6 Rate per Uni t 

Type Degreaser (1o3~t/yr) National ly (WY~) 

Cold Cleaners 

Open Top Vapor 200 

Degreasers 

Conveyori zed 100 

Degreasers 

*380 emission = 450 consumption (from Table 2-2) minus 25 for wiping losses, 

25 for conveyorized cold cleaning and 20 for non-evaporative waste solvent 

disposal (incineration and non-evaporating landfill encapsulation). 
EPA-450/2-77-022 


November 1977 

(OAQPS NO. 1.2-079) 

OAQPS GUIDELINES 

CONTROL OF VOLATILE 

ORGANIC EMISSIONS 

FROM 

SOLVENT METAL CLEANING 

U.S. ENVIRONMENTAL PROTECTION AGENCY 

Office of Air and Waste Management -

Office of Air Quality Planning and Standards 

328 

Research Triangle Park, North Carolina 277 1 1 

RADIAN LIBRARY 


DURHAM, N.C. 

I 
This report is issued by the Environmental Protection Agency to report 

technical data of interest to a limited number of readers. Copies are 

available free of charge to Federal employees, current contractors and 

grantees, and nonprofit organizations - in limited quantities - from the 

Library Services Office (MD-351, Research Triangle Park, North Carolina 

2771 1; or, for a fee, from the National Technical Information Service, 

5285 Port Royal Road, Springfield, Virginia 22161. 

Publ ication No. EPA-45012-77-022 
PREFACE 

The purpose of this document is to inform regional, State, and local 

air pol 1 ution control agencies of the different techniques available for 

reducing organic emissions from solvent metal cleaning (degreasing) . Sol vent 

metal cleaning includes the use of equipment from any of three broad categories: 

cold cleaners, open top vapor degreasers , and conveyori zed degreasers. A1 1 

of these employ organic solvents to remove soluble impurities from metal 

surfaces. 

The diversity in designs and applications of degreasers make an emission 

1imi t approach inappropriate; rather, regulations based on equipment specifications 

and operating requirements are recorrmended. Reasonably available control 

technology (RACT) for these sources entails implementation of operating 

procedures which minimize solventbss and retrofit of applicable control devices. 

Required control equipment can be as simple as a manual cover or as complex 

as a carbon adsorption system, depending on the size and design of the 

degreaser. Requi red operating procedures incl ude covering degreasing 

equi prnent whenever possible, properly using sol vent sprays, reducing the amount 

of solvent carried out of the unit on cleaned work by various means, promptly 

repairing leaking equipment, and most importantly properly disposing of wastes 

containing volatile organics. Not all controls and procedures will be applicable 

to a1 1 degreasers, a1 though in general specific operating requirements and 

control devices will be applicable to the majority of designs within each 

category of degreasers. Control of open top and conveyorized .vapor 

degreasing is the most cost effective, followed by waste sol vent disposal 

for a1 1 degreasing operations, manufacturing cold cleaning and maintenance 

col d cleaning. 

iii 
Two levels of control for each type of degreaser have been identified 

here as examples of reasonably available control technology (RACT). In general, 

control level A shows proper operating practice and simple, inexpensive 

control equipment. Control level B consists of level A plus additional 

requirements to improve the effectiveness of control. The degree of 

emission reduction for both individual items and control levels are 

discussed in the text. Specific requirements can be modified to achieve 

whatever level of control is necessary. Control systems for cold cleaners 

are shown in Table 1, those fbr open top vapor degreasers in Table 2, and 

those for conveyorized degreasers in Table 3. 

Two exemptions are recommended. Fi rst, conveyori zed degreasers small er 

2 than 2.0 m of airlvapor interface should be exempt from a requirement for 

a major control device. This would not be cost effective and would tend to 

move the small conveyorized degreaser users to open top vapor degreasers 

which emit more solvent per unit work load. Second, open top vapor degreasers 

2 smaller than 1 m of open area should be exempt from the application of 

refrigerated chillers or carbon adsorbers. Again, requirement for these 

would not be cost effective. 
TABLE 1. CONTROL SYSTEMS FOR COLD CLEANING 

Control System A 

Control Equipment: 

1. Cover 

2. Facility for draining cleaned oarts 

3. Permanent, conspicuous label, summarizing the operatino requirements 

Operating Requirements: 

1. Do not dispose of waste solvent or transfer it to another Darty, 

such that greater th!n 20 percent of the waste (by weight) can evaporate 

into the atmosohere. Store waste. solvent onlv in covered containers. 

2. Close degreaser cover whenever not handling parts in the cleaner. 

3. Drain cleaned parts for at least 15 seconds or until dripping ceases. 

Control System 0 

Control Equipment: 

1. Cover: Same as fn System A, except if (a) solvent volatility is 

reater than 2 kPa (15 mn Hg or 0.3 psi) measured at 38°C (lOO°F) .** 4b) solvent is agitated, or (c) solvent is heated, then the cover must 

be designed so that it can be easily operated with one hand. (Covers for 

lar~er deqreasers may require mechanical assistance, by spring ;oading, 

countenreiqhtinq or Dowered systems.) 

2. Drainage facility: Same as in System A, except that if solvent 

volatility is greater than about 4.3 kPa (32 mn Hg or 0.6 psi) ~easured at 

38°C (10O0F), then the drainage facility mst be internal, so that oarts are enclosed under the cover while draining. The drainage facility may be 

external for applications where an internal type cannot fit into the cleaning 

system. 

3. Label : Same as in System A 

4. If used, the solvent spray must be a solid, fluid stream (not a 

fine, atomized or shower type spray) and at a pressure which does not cause excessive splashing. 

5. Major control device for highly volatile solvents: If the solvent 

volatility 1s > 4.3 kPa (33 n Hg w 0.6 psi) measured at 38°C (lT)O°F), or ifsolvent is heated above 50'C C120°F], then one of the following control 

devices must be used: 

a. Freehoard that gives a freeboard ratiof** 2 0.7 

h. Yater cover (solvent must be insoluble in and heavier than water) 

c. Other system of equivalent control, such as a refrigerated chiller or carbon adsorption. 

Operating R~rp~irprnentr: 

Sane as in System A 

%:er and sol'd waste regulations must also be cornolied Kith. 

**Senerally solvents consisting primarily ~f mineral Ioirits !Z!oddard) have 

rolatilities c 2 kPa. 

***Freeboard ratio is defined as the freeooard heiqnt divided oj the 

width of :he degreaser. 
TABLE 2. COMPLETE CONTROL SYSTEMS FOR OPEN TOP VAPOR DEGREASERS 

Control System A 

Contrcl Equipment : 

1. Cover that can be opened and closed easily without disturbing the 

vapor zone. 

Operating Requirements: 

1. Keep cover closed at all times except when processing work loads 

through the degreaser. 

2. Minimize solvent carry-out by the following measures: 

a. Rack parts to allow full drainage. 

b. Move parts in and out of the degreaser at less than 3.3 mlsec (11 ftlmin) 

c. Degrease the work load in the vapor zone at least 30 s~c. or until 

condensation ceases. d. Tip out any pools of solvent on the cleaned parts before removal. e. Allow parts to dry within the degreaser for at least 15 sec. or until 

visually dry. . - 3. Do not degrease porous or absorbent materials, such as cloth, leather, 

wood or rope. 

4. Work loads should not occupy more than half of the degreaser's open 

top area. 

5. The vapor level should not drop more than 10 crn (4 in) when the 

work load enters the vapor zone. 

6. Never spray above the vapor 1 eve1 . 

7. Repair solvent leaks imnediately, or shutdown the degreaser. 

8. Do not dispose of waste solvent or transfer it to another party such that greater than 20 percent of the waste (by weight) will 

evaporate into the atmosphere. Store waste solvent only in closed containers. 

3. Exhaust ventilation should not exceed 20 m3/min per m2 (65 cfm per ft 2)

of degreaser open area, unless necessary to meet OSHA requirements. Ventilation 

fans should not be used near the degreaser opening. 

10. Water should not be visually detectable in solvent exiting the water 

separator. 

Contro: System B 

Control Equipment: 

1. Cover (same as in syztem A). 

2. Safety switchfs 

a. Condenser flow zwitctt ana tfermostat - [snuts off sump neat if condenser 

coolant is either not circulating or too warm). 

b. Spray safety switch - (shuts off spray pump if the vapor level drops excessively, about 10 cm (4 in). 

3. Major Control Device: 

Either: a. Freeboar$ ratio reater than or equal to 0.75, and if the 

degreaser opening is > 1 m (10 ft 9 ), the cover must be powered, 

b. Refrigerated chiller, c. Enclosed design (cover or door opens only when the dry part 

is actual 1 y entering or exiting the degreaser .) , d. Carbon adsorption system, with ventilation L 15 m3/min per m2 

(50 cfmlft ) of airlvapor area (when cover is open), and exhausting 45 ppm 

solvent averaged over one complete adsorption cycle, or e. Control svstem. demonstrated to have control efficiency, equivalent to or better than any of the above. 

4. Permanent, conspicuous label, sumnarizing operating procedures #1 to 116. 

Operating Requirements : 

Same as in System A 
TABLE 3. CONTROL SYSTEMS FOR CONUEYORIZED DEGREASERS 

Control System A 

Control Equipment: None 

Operating Requirements : 

3 1. Exhaust ventilation should not exceed 20 m /min per m 2 (65 cfm per ft2) 

of degreaser opening, unless necessary to meet OSHA requirements. Work place 

fans should not be used near the degreaser opening. 

2. Minimize carry-out emissions by: 

a. Racking parts for best drainage. 

b. Maintaining verticle conveyor speed at < 3.3 m/min (11 ftlmin) 

3. Do not dispose of waste solvent or transfer it to another party such 

that greater than 20 percent of the waste (by weight) can evaporate 

into the atmosphere. Store waste solvent only In covered containers. 

4. Repair solvent leaks imnediately, or shutdown the degreaser. 

5. Water should not be visibly detectable in the solvent exiting the 

water separator. 

Control System B 

Control Equipment : 

1. Major control devices; the degreaser must be controlled by either: 

a. Refrigerated chiller, 

b. Carbon adsorption system, with ventilation 5 15 m2/min per m 

2 (50 cfm/ft 2) 

of air/vapor area (when down-time covers are open), and exhausting <25 ppm of 

solvent by volume averaged over a complete adsorption cycle, or 

c. System demonstrated to have control efficiency ?quivalent to or better 

than either of the above. 

2. Either a drying tunnel, or another means such as rotating (tumbling) 

basket, sufficient to prevent cleaned parts from carrying out solvent 1 iquid 

or vapor. 

3. Safety switches 

a. Condenser flow switch and thermostat - (shuts off sump heat if 

coolant is either not circulating or too warm). 

6. Spray safety switch - (shuts off spray pump or conveyor if the vapor 

level drops excessively, e.g. > 10 cm (4 in.)). 

c. Vapor level control thermostat - (shuts off sump heat when vapor 

level rises too high). 

4. Minimized openings: Entrances and exits should silhouette work 

loads so that the average clearance (between parts and the edge of the 

degreaser opening) is either ~10cm (4 in.) or <10 percent of the width 

of the opening. 

5. Down-time covers: Covers should he provided for closing off the 

entrance and exit during shutdown hours. 

Operating Requirements: 

1. to 5. Same as for System A 

6. Down-time cover must be placed over entrances and exits of conveyorized 

degreasers immediately after the conveyor and exhaust are shutdown 

and removed just before they are started up. 
TABLE OF CONTENTS 

Fage 


Preface ................................. iii 


Chapter 1.0 Introduction and Summary .................. 1-1 


1.1 Need to Regulate Solvent Metal Cleaning .......... 1-1 


1.2 Regulatory Approach .................... 1-2 


Chapter 2.0 Sources and Types of Emissions ............... 2-1 


2.1 Industry Description .................... 2-1 


2.2 Types of Degreasers and Their Emissions .......... 2-4 


2.2.1 Cold Cleaners .................... 2-7 


2.2.1.1 Design and Operation ............ 2-7 


2.2.1.2 Emissions ................. 2-12 


2.2.2 Open Top Vapor Degreasers .............. 2-16 


2.2.2.1 Design and Operation ............ 2-16 


2.2.2.2 Emissions ................. 2-25 


2.2.3 Conveyorized Degreasing ............... 2-33 


2.2.3.1 Design and Operation ............ 2-33 


2.2.3.2 Emissions ................. 2-39 


2.4 References ........................ 2-45 


Chapter 3.0 Emission Control Technology ................ 3-1 


3.1 Emission Control Devices ................. 3-1 


3.1.1 Emission Control Devices .............. 3-1 


3.1.1.1 Improved Cover ............... 3-2 


3.1.1.2 High Freeboard ............... 3-5 


viii 
Page 

. ............ 3 -1 1.3 Refrigerated Chi 1 lers 3-6


3.1 .1.4 Carbon Adsorption ............. 3-9


3.1.1.5 Safety Switches ............... 3-14


3.1.2 ' Controls to Flini'rnize Carry-Out ............ 3-16 


3.1.3 Controls for Both Solvent Bath and 

Carry-Out Emi'ssions Combined ............ 3-18 


3.1.3.1 
 Automated Cover-Conveyor System ....... 3-18 


3.1.3.2 
 Refrigeration Condensation ......... 3-20 


3.1.4 Control 
of Naste Solvent Evaporation ......... 3-22 


3.1.4.1 
 Cum-ent Practices .............. 3-22 


3.1.4.2 
 Recommended Practi.ces ............ 3-23 


3.1.5 Other Control Dwi'ces ................ 3-27 


3.1.5.1 Inci'neration ................ 3-28 


3.1.5.2 LiquTd Absorption .............. 3-28 


3.2 Complete Control Systems .................. 3-29 


3.2.1 Cold Cleaning Control Systems ............ 3-30 


3.2.2 Control Systems for Open Top Vapor 

Degreasing ...................... 3-32 


3.2.3 Control Systems for Conveyorized Degreasers ..... 3-32 


3.3 References ......................... 3-37 


Chapter 4.0 Cost Analysis ........................ 4-1 


4.1 Introduction ........................ 4-1 


4.1.1 Purpose ....................... 4-1 


4.1.2 Scope ........................ 4-1 


4.1.3 Model Plants ..................... 4-2 


4.1.4 Capi'tal Cost Estimates ................ 4-3 


4.1.5 Annualized Costs ................... 4-3 

Page 

4.2 Cold Cleaners ........................ 4-4 


4.2.1 Model Plant Parameters ................. 4-4 


4.2.2 Control Costs .................... 4-0 


4.3 Open Top Vapor Degreasers .................. 4-8 


4.3.1 Model Plant Parameters ................ 4-8 


4.3.2 Control Costs .................... 4-8 


4.3.3 Cost Effectiveness .................. 4-14 


4.4 Conveyorized Degreasers ................... 4-16 


4.4.1 Model Plant Parameters ................ 5-10 


4.4.2 Control Costs .................... 4-18 


4.4.3 Cost Effectiveness .................. 4-20 


4.5 References ......................... 4-24 


Chapter 5.0 Adverse Environmental Effects of Applying 

The Technology ........................ 5-1 


5.1 Air Impacts ......................... 5-1 


5.2 Water Impacts ........................ 5.1 


5.2.1 Naste Solvent Disposal ................ 5-1 


5.2.2 Steam Condensate from Carbon Adsorpti'on ....... 5-2 


5.2.2.1 Chlorinated Solvent ih Steam 

Condensate ................. 5-2 


5.2.2.2 Stabilizers in Steam Condensate ....... 5-3 


5.2.3 Effluents from Water Separators ........... 5-4 


5.3 Solid Waste Impact ..................... 5-4 


5.4 Energy Impact ........................ 5-5 


5.5 Other Environmental Concerns ................ 5-6 


5.6 References ......................... 5-8 


Chapter 6.0 Compl iance Testing Methods and Monitori'ng 

Techniques ......................... 6-1 

Page 

6.1 Observation of Control EglQment and 

Operating Practi'ces .................... 6-2 


6.2 Material Balance ..................... 6-2 


6.3 Other Emission Tests ................... 6-3 


Chapter7.0 Enforcement Aspects .................... 7-1 


7.1 Regulatory Approaches ................... 7-2 


7.1.1 Emission Standards ................. 7-2 


7.1 .2 Equipment Standards ................ 7-3 


7.1.3 Operati'onal Standards ............... 7-4 


7.1.4 Solvent Exemptton Standards ............ 7-5 


7.2 Affected Facilities .Prtariiies ............. 7-5 


7.2.1 Definitions of Affected Facilities ......... 7-51 


7.2.2 Priorities of Enforcement ............. 7.5 


Appendix A.0 Emission Test Results 

Appendix B .0 Calculations 
v 

LIST OF TABLES 

Page 

Table 1 Control Systems for Cold Cleaning .............. 


Table 2 Control Systems for Open Top Vapor Degreasers ........ v i 


Table 3 Control Systems for Conveyorized Degreasers ......... vi i 


Table 2-1 Common Metal Cleaning Solvents ................ 2-3 


Table 2-2 National Degreasing Solvent Consumption (1974) ........ 2-5 


Table 2-3 Emissions from Solvent Degreasers (19741 ........... 2-6 


Table 3-1 Control Systems for Cold Cleaning .............. 3-31 


Table 3-2 Complete Control Systems for Open Top Vapor Degreasers .... 3-33 


Table 3-3 Control Systems for Conveyorized Degreasers ......... 3-35 


Table 4-1 Cost Parameters for Model Cold Cleaners ........... 4-5 


Table 4-2 Control Costs for Typical Cold Cleaners ........... 4-7 


Table 4-3 Cost Parameters for Model Open Top Yapor Degreasws ..... 4-9 


Table 4-4 Control Cost for Typi'cal Si2e Open Top Yapor Degreaser .... 4-10 


Table 4-5 Control Cost for Small Open Top Vapor Degreaser ....... 4-11 


Table 4-6 Cost Parameters for Plodel Conveyorized Degreasers ...... 4-17 


Tab1e 4-7 Control Costs for Typical Con~eyorized Degreasers ...... 4-19 

Figure 2-1 
 Cold Cleaner ........................ 2-9 


Figure 2-2 
 Cold Cleaner Emission Points ................ 2-13 


Figure 2-3 
 Open Top Vapor Degreaser .................. 2-18 


Figure 2-4 
 Basic Principle for Water Separator for Vapor Degreaser . . 2-20 

Figure 2-5 
 Open Top Degreaser with Offset Condenser Coils ....... 2-21 


Figure 2-6 
 Two Compartment Degreaser with Offset Boili'ng Chamber ... 2-22 

Figure 2-7 
 Two Compartment Degreaser ................. 2-23 


Figure 2-8 
 Degreaser with Lip Exhaust ................. 2-24 


Figure 2-9 
 Open Top Vapor Degreaser Emission Points .......... 2-26 


LIST OF FIGURES 

Page 

Figure 2-10 Cross Rod Conveyorized Degreaser .............. 2-35 


Figure 2-11 Monorail Conveyorized Degreaser .............. 2-36 


Figure 2-12 Vibra Degreaser ...................... 2-37 


Figure 2-13 Ferris Wheel Degreaser ................... 2-38 


Figure 2-14 Mesh Belt Conveyorized Degreaser .............. 2-40 


Figure 2-15 Conveyorized Degreas.er Emissi.on Points ........... 2-42 


Figure 3-1 
 Refrigerated Freeboard Chiller ............... 3-7 


Figure 3-2 
 Carbon Adsorber ...................... 3-10 


Figure 3-5 
 Elevator Design of Degreaser .Vapor Type ......... 3-19 


Figure 3-6 
 Vapor Pressures of Several Solvents ............ 3-21 


Figure 3-7 
 External Sti:ll ....................... 3-25 


Figure 3-3 

Figure 3-4 


Adsorption Cycle ...................... 3-.11 


Desorption Cycle ...................... 3-12 


Figure 4-1 Cost-Effectiveness of A1 ternative Control Options for 

Existing Open Top Vapor Degreasers ............. 4-15 


Figure 4-2 Cost-Ef fecti~eness of A1 ternative Control Options for 

Existing Monorail Degreas-ers ................ 4-21 


Figure 4-3 Cost-Effectiveness of Alternative Control 0pti:ons for 

Existing Cross-Rod Degreasers ............... 4-23 


xiii 
1,O INTRODUCTION AND SUMMARY 

The purpose of EPA's series of control technique guideline documents 

is to provide guidance on emission reduction techniques which can be applied 

to existing sources in specific industries. The documents are to be used to 

assist States in revising their implementation plans (SIP'S) to attain and 

maihtain National Ambient Air Quality Standards (NAAQS). This document discusses 

vol ati le organic compound (VOC) emissions and appl icable control techniques 

for organic sol vent metal cleaning operations (degreasi ng with sol vents). 

1.1 NEED TO REGULATE SOLVENT METAL CLEANING 

Solvent metal cleaning is a significant source of volatile organic 

compounds (VOC) and tends to be concentrated in urban areas where the 

oxidant NAAQS is likely to be exceeded. In 1975 solvent metal cleaning 

emitted about 725 thousand metric tons of organics. This represents 

about four percent of the national organic emissions from stationary 

sources. Presently, solvent metal cleaning is the fifth largest stationary 

source of organic emissions. Although emissions from solvent degreasing 

(i .e., metal cleaning) represent about four percent of nationwide VOC 

sources, the proportion is significantly higher in most urban areas, 

because of their high concentration of metalworking industries. For example, 
the Southern California Air Qua1ity Management District estimates that 14.8 

percent of the stationary organic emissions in Los Angeles County are 

attributable to sol vent degreasing. 

Control technol ogy is avai 1 able to reduce hydrocarbon emissions from 

existing sol vent metal cleaning operations. However, this technol ogy has 

not been broadly applied largely because of unawareness of economic 

incentives and the absence of regulatory requirements. In 1974, for example, 

16 states covered degreasi ng operations with sol vent regulations identi cal 

or similar to Rule 66 of the Los Angeles County Air Pollution Control District. 

Since then, additional state and local agencies have adopted the same types of 

statutes. Generally, up to 3,000 pounds of VOC emissions per day are allowed 

from sources using sol vents considered non-photochemi cal ly reacti ve under 

Rule 66 criteria. Since solvent metal cleaning operations rarely re1 ease 

more than that amount, they have usually complied with Rule 66 regulations 

merely by substitution. Regulatory incentive to institute control technol ogy 

rather than substitution is necessary to achieve positive emission reduction. 

1.2 REGULATORY APP ROACH 

Photochemi cal oxidant control strategies in the past have re1 ied heavi ly 

on the substitution of solvents of relatively low photochemical reactivity to reduce 

emissions of higher reactivity VOC. Thus, total emissions did not necessarily 

decrease, only the make-up of those emissions changed. One problem with this 

approach was that many solvents classed as low reactivity materials have since 

been found to be moderately and in some cases highly reactive. EPA1s current 

direction and the direction of this document is toward positive reductions of 

all VOC emissions. This is not only more rational from a standpoint of 

conservation but some low reactivity solvents are now suspected of contributing 
to upper atmospheric ozone depletion. These reasons and others support the 

decision to concentrate on positive reduction rather than substitution. 

Positive emission reduction from solvent metal cleaning should be 

attained thpugh use of proper operating practices and retrofit control 

equipment. Proper operating practi ces are those which minimize sol vent 

loss to the atmosphere. These include covering degreasi ng equipment 

whenever possible, proper use of solvent sprays, various means of reducing 

the amount of solvent carried out of the degreaser on cleaned work, prompt 

repair of leaking equipment, and most importantly, proper disposal of wastes 

containing vol ati le organic sol vents. In addition to proper operating 

practices there are many control devices which can be retrofit to degreasers; 

however, because of the diversity in their designs, not all degreasers 

requi re a1 1 control devi ces. Small degreasers using room temperature sol vent 

may require only a cover, whereas a large degreaser using boiling solvent 

may require a refrigerated freeboard chi 1 ler or a carbon adsorption system. 

Two types of control equipment which will be applicable to many degreaser 

de s igns are drainage facilities for c leaned parts and safety switches and 

thermos tats whi ch prevent 1 arge emi ss ions due to equipment malfunction. The 

many degreaser designs along with the emissions characteristi c of those 

designs and the factors affecting those emissions are described in Chapter 2. 

Control devices for each type of emission and control systems for each 

degreaser design are described in Chapter 3. 
2.0 SOURCES AND TYPES OF EMISSIONS 

2.1 INDUSTRY DESCRIPTION 

Solvent metal cleaning describes those processes using non-aqueous 

solvents to clean and remove soils from metal surfaces. These solvents, 

which are principally derived from petroleum, include petroleum distillates, 

chlorinated hydrocarbons, ketones, and a1 coho1 s. Organic solvents such as 

these can be used alone or in blends to remove water insoluble soils for 

cleaning purposes and to prepare parts for painting, plating, repair, 

inspection, assembly, heat treatment or machining. 

Solvent metal cleaning is usually chosen after experience has indicated 

that satisfactory cleaning is not obtained with water or detergent solutions. 

Availability, low cost and farni:iaril,y combine to make water the first 

consideration for cleaning; however, water has several limitations as a 

cleaning agent. For example, it exhibits low solubility for many organic 

soils, a slow drying rate, electrical conductivity, a high surface tension 

and a propensity for rusting ferrous metals and staining non-ferrous metals. 

A1 1 of these 1ini tations can be overcome with the use of organic solvents. 

A typical industrial degreasing solvent would be expected to dissolve 

oils, greases, waxes, tars, and in some cases water. Insoluble matter such 

as sand, metal chips, buffing abrasives or fibers, held by the soils, are 

flushed away. 
A broad spectrum of organic solvents is available. Choices among the 

solvents are based on the solubility of the soil, toxicity, flammability, 

evaporation rate, effect on non-metal li c portions of the part cleaned and 

numerous other properties. The most important properties of sol vents 

conmonly used in metal cleaning are summarized in Table 2-1. 

As would be expected, the metal working industry is the major user of 

solvent metal cleaning. Eight SIC codes (Numbers 25 and 33 to 39) cover 

these industry categories. Examples of industries within these classi fi cations 

are autornoti ve, electronics, appliances, furniture, jewelry, plumbing , 

aircraft, refrigeration, business machinery and fasteners. A1 1 are frequent 

users of organic solvents for metal cleaning. However, the use of solvents 

for metal cleaning is not limited to these industries; solvent metal cleaning 

is also used in non-metal working industries such as printing, chemicals, 

plastics, rubber, textiles, glass, paper and electric power. Often, the 

function of the organic solvents in these industries is to provide maintenance 

cleaning of electric motors, fork lift trucks, printing presses, etc. Even in 

non-manufacturing industries, solvent metal cleaning is commonplace. Most 

automotive, rai 1 road, bus, aircraft, truck and electric tool repair stations 

use these sol vents. In short, most businesses perform solvent metal cleaning, 

at least part time, if not regularly. The number of companies routinely using 

sol vent metal cleaning operations probably exceeds one mil 1 ion. Furthermore, 

large scale users may often have over 100 separate degreasing operations at 

one plant location. 

Solvent metal cleaning is broken into three major categories: cold 

cleaning, open top vapor degreasi ng and conveyorized degreasi ng. In cold 

cleaning operations, all types of solvents are used depending on the type 

of parts to be cleaned. Vapor degreasing uses halogenated solvents because 
Table 2-1 

COMMON METAL CLEANING SOLVENTS**** 


Solvency for Water 


Type of Solvent/ 

Solvent 

Metal Working 

-Soils 

Toxicity 

(PP~ 

Flash 

Point 

Evaporation 

Rate" 

Solubility 

(t wt.) 

Boiling Point 

(Range) 

Pounds 

Per Gal. 

Price 

Per Gal. 

Alcohols 

Ethanol (959) 

Isopropanol 

Poor 

poor 

1000' 

400' 

Methanol poor 200* 

Aliphatic Hydrocarbons 

Heptane good 500* 

Kerosene good 500 

S toddard 

Mineral Spirits 66 

good

good 

200 

200 

Aromatic Hydrocarbons 

Benzene*** good lo* 

FO 

w 

' SC 150 

Toluene 

Turpentine 

Xy lene 

good 

good 

good 

good 

200 

200' 

loo* 

loo* 

Chlorinated Solvents 

Carbon Tetrachloridee** excellent lo* none 111 <0.1 170-172°F 13.22 $ 3.70 

Methylene Chloride excellent SOO* none 363 0.2 104-105.SoF 10.96 $ 2.83 

Perchloroethylene 

1, 1, 1-Trichloroethane 

excellent 

excellent 

loo* 

350* none 

none 16 103 

<0.1 

(0.1 

250-254°F 

165-194'F 

13.47 

10.97 

$ 3.33 

$ 2.73 

Trichloroethylene excellent loo* none 62.4 <O .1 188-190°F 12-14 $ 3.13 

Fluorinated Solvents 

Trichlorotrifluoroethane (PC-113) lOOO* none 439 <0.1 117°F 13.16 $7.84 

Ketones 

Acetone lOOO* 

Methyl ethyl ketone 200' 

*Federal Register, June 27, 1974, Vol. 39, No. 125. 


**Evaporation Rate determined by weight lose of SO mlr, in a 125 ml beaker on an analytical balance (Dow Chemical Co. ~thod). 

***Not reconmended or sold for metal cleaning (formerly standards in industry). 


****Primary source from The Solvents and Chemicals Companies .Physical Properties of Commn Organic Solventsw and Price List 

(July 1, 1975). 

they are not flammable and their vapors are much heavier than air. 

The most recent estimates are that there are l,3OO,OOO cold 

cleaning units in the United States, with about 70 percent of these 

devoted to maintenance or servicing operations and the remainder used 

for manufacturing operations. There are a1 so an es timated 22,000 open 

top vapor degreasers and 4,000 conveyorized degreasers. Of the estimated 

726,000 metric tons per year of solvent used for degreasing, roughly 60 

percent is for cold cleaning, 25 percent for open top vapor degreasing 

and 15 percent for conveyorized degreasing. Tables 2-2 and 2-3 summarize 

the above information. Emissions are discussed in detail in the next 

chapter. 

2.2 TYPES OF DEGREASERS AND THEIR EMISSIONS 

There are three basic types of organic solvent degreasers: cold 

cleaners , open top vapor degreasers , and conveyori zed degreasers . Col d 

cleaners are usually the simplest and least expensive. Their solvent is 

usually near room temperature, but is sometimes heated. The temperature, 

however, always remains below the solvent's boiling point. A cold cleaner 

is a tank of solvent usually including a cover for nonuse periods. Inside 

is a work surface or basket suspended over the solvent. An open top vapor 

degreaser resembles a large cold cleaner; however, the solvent is heated to 

its boiling point. This creates a zone of solvent vapor that is contained by 

a set of cooling coi 1s. Both the cold cleaner and the open top vapor degreaser 

clean individual batches of parts; thus, they are termed "batch loaded". A 

conveyori zed degreaser is 1 oaded continuously by means of various types of conveyor 

systems, and may either operate as a vapor degreaser as a cold cleaner. 
- - 

Table 2-2 

National Degreasing Sol vent Consumption* (1974) 

9 


Solvent Consumption (lo3 metric tons) 

Sol vent Type Cold cleaning Vapor degreasing A1 1 degreasing 

Halogenated: 

Trichl oroethylene 25 128 153 

1,l ,1 Trichloroethane 82 80 162 

Perch1 oroethyl ene 13 41 54 

Methyl ene Chloride 23 7 30 

Trichlorotri fluoroethane 10 2 0 30 

153 276 429 

A1iphatics 

Aroma tics : 

Benzene 

To1 uene 

Xyl ene 

Cycl ohexane 

Heavy Aromatics 

Oxygenated: 

Ketones : 

Acetone 10 

Methyl Ethyl Ketone 8 

Bu tyl 5 

Ethers 

*-* 

Total Sol vents : 450 276*** 726 

Range of Accuracy: (+125) (225) (+145) 

*See Appendix B.l for background on the above estimates. ** 

Includes 25,000 metric tone5from non boi 1 ing convevorized degreasers. *** 

Iqcludes 75,000 metric tons from conveyori zed vapor degreasers. 
Table 2-3 

Emissions from Solvent Degreasers (1974) 

Estimated National 

Emi ssion 

Approximate 

No. of Units 

Averaged Emissi on 

Rate oer Unit 

Type Degreaser National lyCold Cleaners 

Open Top Vapor 200 

Degreasers 

Conveyorized 100 

Degreasers 

*380 emission = 450 consumption (from Table 2-2) minus 25 for wiping losses, 

25 for conveyorized cold cleaning and 20 for non-evaporative waste solvent 

disposal (incineration and non-evaporating landfill encapsulation). 
2.2.1 Cold Cleaners 

Cold cleaner operations include spraying, brushing, flushing and 

imnersion. The solvent occasionally is heated in cold cleaners but always 

remains well below its boiling point. 

Cold cleaners are defined here not to include nonboiling conveyorized 

degreasers which are covered in Section 2.3. Wipe cleaning is also not 

included. 

Cold cleaners are estimated to result in the largest total emission 

of the three categories of degreasers. This is primarily because of the 

extremely large number of these units (over 1 million nationally) and because 

much of the disposed of waste solvent is allowed to evaporate. It is 

estimated that cold cleaners emit 380 thousand metric tons of organics per 

year, this being about 55 percent of the national degreasing emissions 

(see Appendix B. 1) . Cold cleaning solvents nationally account for almost 

all of the aliphatic, aromatic, and oxygenated degreasing solvents and 

about one-third of halogenated degreasing solvents. 

Despite the large aggregate emission, the average cold cleaning unit 

generally mits only about one-thi rd ton per year of organics , with about 

one-half to three-fourths of that emission resulting from evaporation of 

the waste solvent at a disposal site. 

2.2.1.1 Design and Operation -
Typical Model - A typical cold cleaner is shown in Figure 2-2. The 

dirty parts are cleaned manually by spraying and by soaking in the dip tank. 

The solvent in the dip tank is often agitated to enhance the cleaning action. 

After cleaning, the basket of cleaned parts may be suspended over the solvent 

to allow the parts to drain, or the cleaned parts may be drained on an 

external drainage rack (not shown) which routes the drained solvent back into 

the cleaner. The cover is intended to be closed whenever parts are not being 

handled in the cleaner. The cold cleaner described and shown in Figure 2-1 

is most often used for maintenance cleaning of metal parts. A typical size 

2
 of sbch a maintenance cold cleaner is about 0.4 m (4 ft2) of opening and 

3 about 0.1 n (30 gallon) capacity. 

Applications - The two basic types of cold cleaners are maintenance 

cleaners and manufacturing cleaners . The maintenance cold cleaners are usual ly 

simpler, less expensive, and smaller. They are designed principally for 

automotive and general plant maintenance cleaning. 

Manufacturing cold cleaners usually perform a higher qua1 ity of cleaning 

than do maintenance cleaners and are thus nore speci a1 ized. Manufacturing 

cold cleaning is general ly an integral stage in metalworking production. 

Manufacturing cold cleaners are fewer in number than maintenance cleaners 

but tend to emit more solvent per unit because of the larger size and work 

load. Manufacturing cleaners use a wide variety of solvents, whereas 

maintenance cleaners use mainly petroleum solvents such as mineral spiri ts 

(petroleum di s ti11 ates , and Stoddard sol vents ) . Some col d cleaners can 

serve both maintenance and manufacturing purposes and thus are difficult 

to classify. 

The type of cold cleaner to be used for a particular application depends 

on two main factors: (1 ) the work load and (2) the required cleaning 
Figure 2-1 


COLD CLEANER 

Cl eaner 
effectiveness. Work load is a function of tank size, frequency of cleaning, 

and type of parts. Naturally, the larger work loads require larger degreasers. 

The more frequently the cold cleaner is used, the greater the need to automate 

and speed up the cleaning process ; more efficient materi a1 s hand1 i ng sys tems 

help automate, while agitation speeds cleaning. Finally, the type of parts 

to be cleaned is important because more thorough cleaning and draining 

techniques are necessitated for more complexly shaped parts. 

The required cleaning effectiveness establ ishes the choi ce of solvent 

and the degree of agitation. For greater cleaning effectiveness, more 

powerful solvents and more vigorous agitation are used. Seneral ly, emissions 

will increase with agitation and with higher solvency. 

Equipment Design - A1 though cl assif.ying cold cleaners according to 

maintenance or manufacturing application is a convenient initial approach, 

manufacturing cold cleaners vary so widely in design that no one typical 

design can adequately describe them. Thus, a more specific classification of 

manufacturing cold cleaners must also co~nsider the equipment design. The 

most important design factors are tank design, agitation technique, and the 

material handling of parts to be cleaned. 

The two basic tank designs are the simple spray sink and the drip tank. 

The sinple spray sink is usually less expensive. It is more appropriate for 

cleaning appl ications that are not difficult and require only a relatively 

low degree of cleanliness. The dip tank provides more thorough cleaning 

through soaking of dirty parts. Dip tanks also can employ agitation, which 

improves cleaning efficiency. 

Agitation is generally accomplished through use of pumping, compressed 

air, vertical motion or ultrasonics. In the pump agitated cold cleaner, 

the solvent is rapidly circulated in the soaking tank. Air agitation involves 
dispersing compressed air from the bottom of the soaking tank; the air bubbles 

providing a scrubbing action. In the vertical ly agitated cold cleaner, dirty 

parts move up and down while submerged in order to enhance the cleaning process. 

Finally, in the ultrasonically agitated tank, the solvent is vibrated by high 

frequency sound waves. Ultrasonically agitated 1 iquids often need to be heated 

to speci fi c temperatures to achieve optimum cavitation. Cavitation is the 

implosion of microscopic vapor cavities within the liquid solvent. The implosions, 

which are caused by pressure differentials of the sound waves in the solvent, 

break down the dirt film on the parts. 

The designs for material hand1 ing in cold cleaning systems are almost 

endless, but they are general ly di vided into manual and batchloaded conveyorized 

systems. (Continuously loaded conveyorized systems are described separately in 

Section 2.3). Manual loading is used for simple, small-scale cleaning operations 

and is self explanatory. Batchloaded conveyorized systems are for use in the 

11lore complex, larger-scale cleaning operations. These systems may include an 

automated dip, which automati cally lowers, pauses, and raises the work 1 oad. 

They may also include systems, such as a roller conveyor, to transfer the work 

load to other operations. In another variation, two or more dip tanks may be 

used in series. These tanks may contain increasingly pure solvent in a "cascade" 

cleaning system. The consecutive dip tanks may also contain different cleaning 

solutions for more complex operations and may even be combined with vapor 

cleaning and aqueous systems. 

The materials handling technique can be important in reducing emissions 

from cold cleaning. Regardless of the system, the work loads need to be handled 

so that the solvent has sufficient time to drain from the cleaned parts into an 

appropriate container. Drainage faci lities are described in Section 3.1.2. 
2.2.1.2 Emissions -

Sol vent evaporates both di rectly and indirectly from the cold cleaners. 

The emission rates vary widely; nevertheless, the average emission rate, 

calculated from national consumption data, is estimated to be about 0.3 

metric ton per year. Maintenance and manufacturing cold cleaners are 

estimated to emit approximately 0.25 and 0.5 metric tons per year, respectively 

(see Ap~endix 8.2.2). Data from the Safety Kleen Corporation reports only 

0.17 metric tons per year for thier cold cleaner. However, their emissions 

are expected to be lower than others because most of the waste solvent from 

Safety Kleen units is distilled and recycled by the company. 

Emissions from a cold cleaner occur through: (1) bath evaporation, (2) 

solvent carry-out, (3) agitation, (4) waste sol vent evaporation, and (5) 

spray evaporation. These are depicted in Figure 2-2 and discussed in thp 

following sections. 

Bath Evaporation - Bath evaporation can be greatly reduced through use of 

a cover. Generally, the cover should be closed whenever the parts are not being 

handled in the cold cleaner. Although covers are standard equipment on most 

cold cleaners, keepi ng the cover closed requires conscientious effort on the part 

of the operator and his su~ervision. As will be discussed in Section 3.1.1, there 

are various means of inducing the operator to close the cover more frequently. 

Where solvents much more volatile than mineral spirits are used, adequate 

freeboard height is important to reduce evaporation. Freeboard height is the 

distance from the solvent to the top edge of the cold cleaner. The requirement 

for freeboard height is most commonly expressed as freeboard ratio, with freeboard 

ratio being defined as the ratio of freeboard height to degreaser width (not 

length). 

Excessive drafts in the workshop can significantly increase solvent bath 

evaporation. Thus, room and exhaust ventilation should be no greater than is 
1. use of a manual cover; 

2. use of a manual or powered cover in combination with extended freeboard; 

3. refrigerated chiller; 

4. carbon adsorber; 

As in the case of cold cleaners, incremental costs for housekeeping 

controls on open top vapor degreasers are not presented because they appear 

to be negligible. 

With regard to conveyorized vapor degreasers, control cost estimates 

will be presented for facilities that primarily use trichloroethylene or 

perchloroethylene solvents. The control cost estimates will reflect the use 

of the following techniques: 

a. carbon adsorber 

b. refrigerated chi1 1ers 

Again, incremental costs for housekeeping are not presented because they. 

appear to be negligible. 

4.1.3 Model Plants 

Control cost estimates are presented for typical model degreasers in the 

metal cleaning industry. Specific model plant parameters will be presented 

in the subsequent portions of this chapter. Admittedly, control costs may 

vary from one installation to another, perhaps even appreciably from the 

costs described for the models in this chapter. However, the difficulty of 

obtaining actual plant control costs requires use of model plants. To the 

extent possible, EPA has incorporated actual plant cost information into the 

cost analysis. 
necessary to provide safe levels for the operator's health and plant's protection. 

Agitation Emissions - Agitation increases emissions. The rate of emission 

depends upon: ( 1 ) use of the cover, (2) aqitation system adjustments and (3) volatility of the solvent. Ifthe cover is kept closed durinq aqitation, then emissions 

usual ly are insignificant. However, agitation emissions can increase dramatically 

with the cover open. This is especially true with ultrasonic agitation of solvents 

heated to their optimum cavitation temperature. The bath should also be agitated for 

no longer than necessary to complete the cleaning. Poor adjustment of the agitation 

system may also increase emissions. In particular, the air flow into air agitated 

3 cleaners should be about 0.01 to 0.03 m per minute per square meter of opening. 

EPA tests on cold cleaners indicate that the volatility of the solvent greatly 

affects emissions due to agitation. Emissions of low volati 1 ity solvents increase 

significantly with agitation; however, contrary to what one might expect, agitation 

causes only a small increase in emissions of high volatility solvents. This is 

believed to be due to the already high unagitated evaporation rate of high volatility 

solvents (see Appendix A). Little difference was found between the eftects ot pump 

agitation and air agitation. 

Carry-3ut Emissions - Carry-out emissions depend on the existence and use of a 

drainage faci 1 ity. Drainage faci 1 i ties are racks or she1 ves used for draining excess 

solvent off cleaned parts. The drainage facility is standard equipment for some cold 

cleaners and is easily and inexpensively retrofitted for most other cold cleaners. 

Drainage facilities are described further in Section 3.1.2. 

Although installation of a drainage facility is usually no problem, it will 

sometimes require a special effort to fully use the facility. As recommended 

from ASTM 0-26, cleaned parts should drain at least 15 seconds .' For rapid 

pace work, such as automotive repair, this time may be perceived as too 
delaying; nonetheless, the 15 second drain time should be adhered to. 

Waste Solvent Evaporation - Waste solvent evaporation is the greatest 

source of emissions from cold cleaning. The amount of waste solvent disposed 

of depends on the size of the cold cleaner and on the frequency of disposal. 

When the cleaning job removes large quantities of oil and other contaminants, 

or requires a high degree of cleanliness, the solvent will be disposed of 

more frequently. Conversely, if the cold cleaner is equipped with an effective 

fi lter, as many cold cleaners present are, then sol id irnpuri ties are removed 

and disposal is required less frequently. 

Waste solvent evaporation depends not only upon the amount but also upon 

the method of disposal. Acceptable methods of handling waste solvent include 

proper inci nerati on, di s ti 1 1 ati on, and chemical landf i1ling , where the waste 

solvent is buried in enclosed containers and encapsulated by impermeable soi 1. 

Disposal routes that result in total emission to the environment include flushin5 

into sewers, spreading waste solvent for dust control, such as on dirt roads, 

and landfilling where the solvent can evaporate or leach into the soil. Waste 

solvent evaporation is discussed further in Section 3.1.4. 

Spray Evaporation - Evaporation from solvent spraying wi 11 increase with 

the pressure of the spray, the fineness of the spray, and tne tenaency iu >p;a>;r 

and overspray out of the tank. Evaporation is also greater when the spray is 

used constantly and when vol ati le solvents are used. Preferrably, the spraying 

pressure should be less than 10 psig, and the spray should be a solid, fluid 

stream.* The solvent loss from overspraying and splashing can usually be 

el irninated by sensible design and careful operation. 

Solvent Type- The type of solvent is a factor that greatly affects the 

emission rate from the cold rleanpr. The volatility of the solvent at the 

o~eratina temerature is the sinale :,lost inoortant variable. 
More toxic organics are rarely used in degreasers, but when they are 

they tend to be much better controlled to protect workers and to comply 

with OSHA regulations. These include carbon tetrachloride, benzene and 

methyl ethyl ketone. 

The price of the solvent influences the care that is taken to conserve 

it. Thus, more expensive solvents are emitted less. In addition, the higher 

the price of the solvent, the more likely that the wastes will be recovered, 

and the more economi cal control wi 11 become. 

2.2.2 Open TOD Va~or Deqreasers 

Vapor degreasers clean through the condensation of hot solvent vapor on 

colder metal parts. Open top vapor degreasers are batch 1 oaded, i,e., they 

clean only one work load at a time. 

Open top vapor degreasers are estimated to result in the second largest 

emission of the three categories of degreasers. It is estimated that open 

top vapor degreasers emit 200 thousand metric tons of organics per year, this 

being about 30 percent of the national degreasing emissions (see Appendix B.3). 

2.2.2.1 Design and Operation -

The Cleaning Process - In the vapor degreaser, solvent vapors condense on 

the parts to be cleaned until the temperature of the parts approaches the boilin( 

point of the solvent. The condensing solvent both dissolves oils and provides a 

washing action to clean the parts. The selected solvents boil at much lower 

temperatures than do the contaminants; thus, the solvent/soil mixture in the 

degreaser boils to produce an essentially pure solvent vapor. 

The simplest cleaning cycle involves lowering the parts into the vapor 

zone so that the condensation action can begin. When condensation\ ceases, the 

parts are slowly withdrawn from the degreaser. Residual liquid solvent on the 
parts rapidly evaporates as the parts are removed from the vapor zone. The 

cleaning action is often increased by spraying the parts with solvent (below 

the vapor level) or by immersing them into the liquid solvent bath. 

Basic Design - A typical vapor degreaser, shown in Figure 2-3, is a 

tank designed to produce and contain solvent vapor. At least one section of 

the tank is equipped with a heating system that uses steam, electricity, or 

fuel combustion to boil the solvent. As the solvent boils, the dense solvent 

vapors displace the air within the equipment. The upper level of these pure 

vapors is controlled by condenser coils located on the sidewalls of the 

degreaser. These coils, which are supplied with a coolant such as water, are 

generally located around the entire inner surface of the degreaser, although 

for some smaller equipment they are limited to a spiral coil at one end of the 

degreaser. Most vapor degreasers are also equipped with a water jacket which 

provides additional cool ing and prevents convection of sol vent vapors up hot 

degreaser wall s. 

The cooling coils must be placed at some distance below the top edge of 

the degreaser to protect the solvent vapor zone from disturbance caused by air 

movement around the equipment. This distance from the top of the vapor zone 

CL- LL, .+a#L tup ~f the degreaser tat-~k ib called the freeboard and is generaliy 

established by the location of the condenser coils. The freeboard is customarily 

50 to 60 percent of the width of the degreaser for solvents with higher boiling 

points, such as perch1 oroethylene, trichloroethylene, and l,l ,l -trichloroethane. 

For sol vents with lower boil ing points, such as trichlorotrifl uoroethane 

and rnethylene chloride, degreasers have normally been designed with a 

freeboard equal to at least 75 percent of the degreaser width. Higher 

freeboards than those recomnended will further reduce solvent emissions; however, 

there comes a point where difficulty associated with moving parts into and out 

+ .
Figure 2-3 

OPEN TOP DEGREASER 

Safety Thermostat 

\ 

Condensing Coils 

Water Jacket 

ondensate Trough 

ater Separator 

Indicator 

Cleanout Door 

Solvent Level Sight c lass/ \ Heating Elements 

Work Rest And Protective Grate 
of a degreaser with a high freeboard outweighs the benefit of increased 

emission control. 

Nearly all vapor degreasers are equipped with a water separator such as 

that depicted in Figure 2-4. The condensed solvent and moisture are collected 

in a trough below the condenser coils and directed to the water separator. The 

water separator is a simple container which allows the water (being immiscible 

and less dense than solvents) to separate from the solvent and decant from the 

system while the solvent flows from the bottom of the chamber back into the 

vapor degreaser. 

Variations in Design - Figure 2-5, 2-6 and 2-7 show the most popular open 

top vapor degreasers in use. These units range in size from table top models 

with open top dimensions of 1 foot by 2 feet up to units which are 110 feet long 

and 6 feet wide. A typical open top vapor degreaser is about 3 feet wide by 6 

feet long. 

Historically, degreasers of the typical size and smaller have been supplied 

with a single piece, unhinged, metal cover. The inconvenience of using this 

cover has resulted in general disuse or, at best, use only during prolonged 

periods when the degreaser would not be operated, for example on weekends. More 

recently, small open top degreasers have been equipped with manual ly operated 

roll -type plastic covers, canvas curtains, or hinged and counter-bal anced metal 

covers. Larger uni ts have been equipped with segmented metal covers. Final ly, 

most of the larger open top vapor degreasers (200 &quare feet and larger) and 

some of the smaller degreasers have had manually controlled powered covers. 

Lip exhausts such as those shown in Figure 2-8 are not uncommon although 

in use on less than half of the existing open top vapor degreasers. These 

exhaust systems are designed to capture solvent vapors escaping from the 

degreasers and carry them away from the operating personnel. To the extent 
Figure 2-4 

BASIC PRINCIPLE FOR WATER SEPARATOR 


FOR VAPOR DEGREASER 

WATER 

=--OUT 

1-


WET SOLVENT 

FROM 

CONDENSER 

(SOLVENT) 

JENT 

OUT 
-- 

Figure 2-5 

OPEN TOP DEG~~WITHOFFSET CONDENSER COILS 

water /\

Jacket 
- - 

Figure 2-6 

TWO COMPARTMENT DEGREASER WITH OFFSET BOILING CHAMBER 

\ 

Solvent Overflow arm Solvent 

Dam Immersion Chamber 
Fiqure 2-7 


TWOCOMPARTMENTDEGREASER 

Immersion Chamber 
Figure 2-8 

DEGREASER WITH LIP EXHAUST 

haust 

c t 
that they disturb the vapor zone, they increase solvent losses.) For 

properly designed exhaust systems, the covers blose below the 

1 ip exhaust inlet level. 

Applications - Open top vapor degreasers are usually 1 ess capital intensive 

than conveyorized systems, but more capital intensive than cold cleaning 

equipment. They are generally located near the work which is to be cleaned at 

convenient sites in the plant, whereas conveyorized vapor dlegreasers tend to be 

located at central cleaning stations requiring transport of parts for cleaning. 

Open top degreasers operate manually and are generally used for only a small 

portion of the workday or shift. 

Open top vapor degreasers are found primarily i~ metal working plants, 

as described previously. Furthermore, the larger the plant the more likely 

it will use vapor degreasers instead of cold cleaners. Vapor degreasers are 

generally not used for ordinary maintenance cleaning of metal parts, because 

cold cleaners can usually do this cleaning at a lower cost. An exception may 

be maintenance cleaning of electrical parts by means of vapor degreasers because 

a high degree of cleanliness is needed and there is ntricacy of design. 

2.2.2.2 Emissions -

Unlike cold cleaners, open top vapor degreasers lose a relatively small 

proportion of their solvent in the waste material an as 1 iquid carry-out. 

Rather, most of the emissions are those vapors that diffuse out of the degreaser. 

As with cold cleaning, open top vapor degreasing emissions depend heavily on 

the operator. The major types of emissions from open top vapor degreasers 

are depicted in Figure 2-9. 

An average open top vapor degreaser emits about 2.5 kilograms per hour 

per m 2 of opening (0.5 pounds per hour f t2) . This estimate is derived from 

national consumption data on vapor degreasing sol vents and from seven EPA 

emission tests summarized in Appendix A. Assuming an average open top vapor 

degreaser would have an open top area of about 1.67 2 

m 

2 (18 ft ), a typical 

emission rate would be 4.2 k ilograms per hour or 9,500 kilograms per year 

(9 pounds per hour or 10 tons per year). 

Diffusion Losses - Diffusion is the escape of solvent vapors from the 

vapor zone out of the degreaser. Solvent vapors mix with air at the top of 

the vapor zone. This mixing increases with drafts and with disturbances 

from cleaned parts being moved tnto and out of the vapor zone. The solvent 

vapors thus diffuse into the room air and into the atmosphere. These solvent 

losses include the convection of warm solvent-laden air upwards out of the 

degreaser. 

Diffusion losses from the open top vapor deg-reaser can be minimized by 

me foll owing actions: 

a. Closing the cover, 

b. Minimizing drafts, 

c. Providing sufficient cooling by the condensing coi 1 s , 

d. Spraying only below the vapor level, 

e. Avoiding excessively massive work loads, 

f. Maintaining an effective water separator, 

g. Promptly repairing leaks. 

The cover must be closed whenever the degreaser is not in use. This 

includes shutdown hours and times between loads. Cover design is also important. 

Improved designs for the cover can make it easier to use thereby facilitating 

more frequent closure. Covers should also be designed to be closed while a 

part is being cleaned in the degreaser. 

Drafts can be minimized by avoiding the use of ventilation fans near the 
degreaser opening and by placing baffles on the windward side of the degreaser. 

A baffle is simply a vertical sheet of material placed along the top of the 

degreaser to shield the degreaser from drafts. 

Sufficient cooling by the condensing coils should be attained by following 

design specifications for the degreaser. Cooling rate is a function of solvent 

type, heat input rate, coolant temperature and coolant flow. If the vapor 

level does not rise above the midpoint of the cooling coils, then the cooling 

4

rate is probably adequate. 

The solvent must not be sprayed above the vapor level because such 

spraying will cause solvent vapors to mix with the air and be emitted. When 

this occurs, the operator should wait for the vapor level to return to normal 

and then should cautiously operate the spray wand only below the vapor level. 

A massive work load will displace a large quantity of solvent vapor. The 

work load should not be so massive that the vapor level drops more than about 

10 cm (4 inches) 5 as the work load is removed from the vapor zone. Otherwise, 

excessive quantities of solvent vapors will mix with the air as the vapor level 

falls and rises. 

The water separator should be kept properly functioning so that water does 

not return to the surface of the boiling solvent sump. Water can combine with 

the solvent to form an azeotrope, a constant boiling mixture of solvent and water 

that has a lower vapor density and higher volatility than does pure solvent 

6 


vapor. 

Lastly, it is important for any leaks to be repaired properly and promptly. 

Special attention should be paid to leaks of hot solvent because hot solvent 

evaporates quickly. These leaks may be greater than they appear or go completely 

unnoticed. 

Carry-Out Emissions - Carry-out emissions are the liquid and vaporous sol vent 

entrained on the clean parts as they are taken out of the degreaser. Crevices 

2- 28 
and cupped portions of the cleaned parts may contain trapped liquids or vapors 

even after the parts appear to be dried. Also, as the hot cleaned part is withdrawn from the vapor zone, it drags up solvent vapors and heats solvent-laden 

air causing it to convect upwards out of the degreaser. 

There are seven factors which directly effect the rate of carry-out 

emissions : 

a. Porosity or absorbency of work loads, 

b. Size of work loads in relation to the degreaser's vapor area, 

c. Racking parts for drainage, 

d. Hoist or conveyor speed, 

e. Cleaning time in the vapor zone, 

f. Solvent trapped in cleaned parts, 

g. Drying time. 

Porous or absorbent materials such as cloth, leather, wood or rope will 

absorb and trap condensed solvent. Such materials should never enter a vapor 

zone. 

The work load preferably should not occupy more than one-half of the 

degreaser's working area.7 Otherwise, vapors will be pushed out of the 

vapor zone by means of a piston effect. 

Proper racking of parts is necessary to minimize entrainment (cupping) of 

solvent. For example, parts should be positioned vertically with cups or 

crevices facing downw'ard. 

A maximum hoist speed of 3.3 meters per minute (11 feet per minute) has been 

general ly accepted as reasonable by the degreasi ng industry. Rushing work 

loads into and out of the degreaser will force solvent vapors out into the air 

and leave liquid solvent on the cleaned parts which can subsequently evaporate 

into the air. 
Cleaning time is the period the work load remains in the vapor zone. 

If this is not long enough to allow the work load to reach the temperature 

of the condensing vapor, the parts will not dry properly when removed from 

the vapor zone. The work load should remain in the. vapor zone until the vapors 

no 1 onger condense on the parts. Usual ly 30 seconds is sufficient; 

10 howe;er, massive work loads may requi re 1 onger periods. 

Before the cleaned parts emerge from the vapor zone, they should be 

tipped and/or rotated to pour out any collected liquid solvent. The work load 

should be removed from the vapor zone slowly (at a vertical speed not to exceed 

11 

11 feet per minute). 

Drying time is critical. It should be long enough to allow the solvent 

to vaporize from the clean part but not significantly longer. When a hot 

dried part rests just above the vapor level , it causes solvent-1 aden ai r to 

12 heat up and rise. Typically a work load can dry in 15 seconds. 

Waste Solvent Evaporation - Solvent emissions may also result from 

disposing of waste solvent sludge in ways where the solvent can evaporate 

into the atmosphere. The volume of waste solvent in sludge from vapor degreasers 

is much less than that from cold cleaners for equivalent work loads for two 

reasons. First, the solvent in the vapor degreaser sump can be allowed to become 

much more contaminated than the solvent used in a cold cleaner because the 

contaminants, with high boiling points, stay in the sump rather than vaporize 

into the vapor zone. Second, vapor degreasing solvents are halogenated and as 

such are generally more expensive; thus, they are more often distilled and 

recycled than cold cleaning sol vents. 

A1 though the waste sol vent evaporation from vapor degreaser sludge is 

usually less than the diffusion and carry-out losses, it still contributes 

about 5 to 20 percent of the degreaser's total solvent emissions. l3When 
the solvent in the sump accumulates too much oil and other contaminants 

problems can occur. The most serious is coating of the heater surfaces, leading 

to overheating and subsequent chemical degradation of the solvent. 

Thus, the solvent sludge must be cleaned out of the degreaser periodically 

and replaced with fresh solvent. 

There are four practices that can reduce and nearly eliminate the 

atmospheric evaporation from waste solvent disposal; 

a. Boi 1 -down, 

b. Use of in-house distillation, 

c. Use of contract reclamation services, 

d. Transfer to acceptable disposal facilities. 

Boil-down is a technique of distilling pure solvent from the contaminated 

mixture in the deg~easer. As the contaminated solvent is boi led in the sump 

pure solvent vaporizes and condenses on the cooling coils where it is routed 

to and stored in a holding tank. Boi 1-down can usually reduce the sol vent 

content in the contaminated material to less than 40 to 45 percent by volume. 

When production schedules permi t further boi 1-down time, considerably 1 ower 

14 levels can be achieved. 

In-house aistillation can be an erricient and often profitabie methoa of 

treating waste solvent. Distilled solvents can nomally be reused although 

additional stabi 1 izers must be added sometimes. Disti 11ation systems vary from 

centralized centers to relatively mall external stills for one or more vapor 

degreasers. Through distil lation, the solvent content of the waste sol vent 

sludge can be reduced to about 20 percent by weight (12-15 percent by volume) 

in most operations. l5 Additional steam stripping can reduce this further. 

Presently most vapor degreaser operators do not use in-house disti 11 ation 
but transfer their waste solvent to another system or company. Even if the 

waste solvent is distilled, there are oils and contaminants, called still 

bottoms, that require disposal. The preferable disposal methods, for 

minimizing sol vent evaporation into the atmosphere, are disti 1 lation plants 

and special incineration plants. Disposal in landfi 11s after evaporation 

is also used but is less desirable. Waste solvent disposal is discussed 

in greater detail in Section 3.1.4. 

Exhaust Emissions - Exhaust systems are often used on larger than average 

open top vapor degreasers. These systems are called lip or lateral exhausts 

and they draw in solvent-laden air around the t9p perimeter of the degreaser. 

Although a collector of emissions, an exhaust system can actually increase 

evaporation from the bath, particularly Sf the exhaust rate is excessive. 

Some exhaust sys tenls include carbon adsorbers to collect the exhaust sol vent 

for reuse; thus, exhaust emissions can be nearly eliminated if the adsorption 

system functions properly. 

In some poorly designed exhaust systems, the ventilation rate can be too 

high. If the air/vapor interface is disrupted by high ventilation rates, more 

solvent vapors will mix with air and be carried out by the exhaust system. A 

rule of thumb used by manufacturers of degreaser equipment and control systems 

is to set the exhaust rate at 50 cubic feet per minute per square foot of 

16 degreaser opening (15 m 3 per minute - m2 ). 

The primary objective of exhausting is to assure that the threshold limit 

value (TLV) as adopted by OSHA is not exceeded. The exhaust level recomended 

above is satisfactory for OSHA requirements on ventilation except when the qualof operation of the degreaser is rated as "average" or "poor." Poor operation 

noted by OSHA to include excess carry-out of the vapor and liquid solvent, 

contamination of the solvent, or improper heat balance. In these cases, and 
for solvents with a TLV -< 100 ~pm, the minimum OSHA ventilation requirement is 

75 or 100 cubic feet per minute per square foot of degreaser opening, 

Consequently, atmospheric emissions from poorly operated degreasers are 

fncreased even further. 

2.2.3 Conveyori zed Degreasi ng 

There are several types of conveyorized degreasers, operating both with 

cold and vaporized solvents. An average conveyorized degreaser emits about 

25 metric tons per year of solvent; however, because of their 1imi ted numbers they 

contribute only about 15 percent of the total solvent degreasing emissions. 

Because of thei r 1 arge work capaci ty conveyori zed degreasers actual 1 y emi t 

less solvent per part cleaned than either open top vapor degreasers or cold 

cleaners. Controls discussed in Chapter 3 can reduce this amount still 

further. 

2.2.3.1 Design and Operation -

In conveyorized equipment, most, and sometimes all, of the manual parts 

handling associated with open top vapor degreasing has been eliminated. 

Conveyori zed degreasers are nearly a1 ways hooded or covered. The encl osure 

of a degreaser diminishes solvent losses from the system as the result of air 

movement within the plant. Conveyorized degreasers are used by a broad 

spectrum of metalworking industries but are most often found in plants where 

there is enough production to provide a constant stream of products to be 

degreased. 

There are seven mai n types of conveyori zed degreasers : monorai 1 , cross-rod , 

vibra, ferris wheel, belt, strip, and circuit board cleaners. While most of the 

seven types of conveyorized degreasers may be used with cold or vaporized solvent, 

the first four are almost always vapor degreasers. 
The cross-rod degreaser (Figure 2-l0)obtai ns its name from the rods 

between the two power driven chains from which parts are supported as they 

are conveyed through the equipment. The parts are contained in pendant 

baskets or, where tumbling of the parts is desi red, perforated cylinders. 

These cylinders are rotated by a rack and pinion design within the solvent 

and/or the vapor zone. This type of equipment lends itself particularly 

well to handling small parts which need to be immersed in solvent to obtain 

satisfactory cleaning or requires tumbling to provide sol vent drainage from 

L 


cavities in the parts. 

A monorai 1 vapor degreaser (~igure 2-11) is usually chosen when the 

parts to be cleaned are being transported between manufacturing operations 

using a monorail conveyor. This design lends itself to automatic cleaning 

with solvent spray and vapor. The parts can be moved in one side and out the 

other, as illustrated, or they can turn 180' while in the vapor or spray 

portions of the equipment and exit the equipment through a tunnel parallel to 

the entrance. 

In a vibra degreaser (Figure 2-12) dirty parts are fed through a chute 

which directs them into a pan flooded with solvent. The pan is connected 

to a spiral elevator. The pan and spiral ele~ator are yi'hrated, 

causing the parts to move from the pan up the spiral to the exit chute. The 

parts condense solvent vapor as they are vibrated up the spiral and dry as 

soon as they leave the vapor zone. These degreasers are capable of processing 

quantities of small parts. Since the vibratory action creates considerable 

noise, acoustical insulation of the equipment is needed or the system must be 

enclosed in a noise-control booth. 

Three other typkal units are the ferris wheel, be1t, and strip degreasers. 

The ferris wheel degreaser (Figure 2-13) is one of the least expensive and 
Figure 2-10 

CROSS-ROD CONVEYORIZED DEGREASER 
Figure 2-1 1 

MONORAIL CONVEYORIZED DEGREASER 

Conve 

Path 

Jacket 
Figure 2-12 

VlBRA DEGREASER 

f 

1 Workload Discharger Chute 

II Ascending 1 '1 

Vibrating 

Trough -

1 

Workload I 

Entry Chuter 

Distillate Return 

Steam Coils 4C 
Figure 2-13 

FERRIS WHEEL DEGREASER 

Work 

Baske 

Gear to tumble 

'baskets 

oil ihg 

Chamber 
sr,ial lest conveyorized degreasers. It general iy uses perforated baskets : 

as does the cross-rod degreaser. The be1 t degreaser is designed to enable 

simple and rapid loading and unloading of parts (see Figure 2-14). f~ strip 

degreaser resembles a belt degreaser, except that the strip itself is being 

cleaned. The strip degreaser is an integral step in the fabrication and 

coating of some sheet metal products. 

Circuit board cleaners are conveyorized degreasers which use one of the 

previously described designs specifical ly in the production of printed circuit 

boards. There are three types of ci rcui t board cleaners : developers, 

strip~ers, and defluxers. In the production of circuit boards, ultraviolet rays 

are projected through a film of an electrical circuit pattern tc create an 

image on a copper sheet covered with resist. The developer degreaser dissolves 

off the unexposed resist. This copper covered board is then dipped in an acid 

bath to etch away the copper that is not covered by the hard, developed 

resist. Next, the stripper degreaser dissolves off the developed resist. 

Then a wave of solder passes over the bare copper circuit and bonds to it. 

Lastly, the defluxcr degreaser dissolves off the flux left after the solder 

hardens. Because of the nature of the materials being cleaned, circuit board 

cleaners can use cold (room temperature) solvents, as well as vapor 

degreasi ng processes. 

2.2.3.2 Emissions -

About 85 percent of the conveyorized degreasers are vapor types, leaving 

15 percent as conveyori zed non-boi 1 ing degreasers. Ci rcui t board cleaners 

represent most of the non-boi i i ng ccnveyori zed degreasers. An average 

emission rate from a conveyorized vapor degreaser is about 25 metric tons 

per year, while that for non-boiling conveyorized degreasers is almost 50 

Ifletri c tons per year. However, most new designs for non-boi 1i ng conveyorized 
Fiaure 2-14 

MESH BELT CONVEYORIZED DEGREASER 

Conveyorpath / 
degreasers are far mcrs e--ficient than the older designs. le It is estimated 

that the vapor types presently ccntribute about 75 percent of the conveyorized 

degreaser erci ssi ons nat? cnal ly and the non-Soi 1i ng types ccntri bute the 

reniaining 25 percent. 3n the national scale, about 75,000 metric tons/year 

are emitted from conveyorized vapor degreasers, and about 25,000 metric tons/ 

year are from conveyorized non-boi ling degreasers (see A~pendix 6.4). The 

major types of etnissions from conveyorized desreasers are depicted in Figure 2-15. 

Bath Evaporation - For an equivalent work load, the diffusion and convection 

of solvent vapors from the solvent bath are considerably less for conveyorized 

degreasers than for open top degreasers. This is because the conveyorized degreasers are normally enclosed except for a relatively small entrance and exit. 

Because conveyorized degreasers are generally automated, operatins practice 

is a minor factor while design and adjustment are major factors affecting 

emissions. Proper adjustment of the degreasing sys tern primari ly affects bath 

evaporation and exhaust emissions, while operation and degreaser design affect 

carry-out and waste solvent evaporation. 

The main adjustment affecting the bath evaporation rate is the heating 

and cooling balance. Basically, the cooling supplied by the primary 

condensing coi 1 s shoul d be suf f i ci ent to condense a1 1 the vapori zed sol vent. 

Also, the heating rate needs to be large enough to prevent the vapor level 

from dropping as cold parts enter the vapor zone. 

With regard to equipment design, bath evaporation can be reduced by 

ginimizing the entrance and exit areas and by regulating the spray system. 19 

Naturally the smaller the area of opening, the lower the loss of solvent 

vapors. Partial covers can be placed over the openings which silhouette the 

parts to be cleaned yet give enough margin for safe passage. Sprays should be 

designed or adjusted so that they do not cause turbulence at the air,/vapor 

interface. Spray pressure should the minimum necessary for proper perfor~ance 

One we71 designed system uses the high pressure spray in a contained and 

parti a1 ly subrilerged chamber. 

Poor operation can increase convective losses frm tne s~l.delltbath. 

For instance, if work baskets are overloaded the vauor zone may collapse 

increasing air vapor mixins and, tkus, emissjons. This can be avoided by 

following the manufacturer's speci ficaticn for a1 lowable work load in tons 

per hour, which is determined thrcugh an enerSLt balance of the syster;,, The 

heating cauacity of the sclj~ent boiler must be greater than the heat loss due 

to solvent condensation cn the work :oad. ti~aporat!ve losses from the bath 

also increase when there is delay in solvent leak repair. 

Carry-Out Enlissions - Carry out of vapor and liquid solvent is usually 

the major emission from conveycrized degreasers. It is difficult to reduce 

carry-out eriiczions, because the amoant of work lead is inherently l arge. 

ds was discussed for opeK top vapor degreasing. Racking is especially critical 

in conveyor1 zed dcr reasers , because there is 1 1ttle an operator can do to 

reduce c3r :-oux -FYF s pr~clly5esigned systei~.. The dcgineaser design s?o~la 

allo:. s~fficiert cn?ce .?+ fire =or the cleaned ;avLz t - drj r,m~:etc;y Tone 

desi~rlsi nclcde 2 si- r~uder tercciing -F ciii the ex't to forn; 2 dsy7nc t~nr,e!. 4?&7n 

the conveyor speed should not exceed 2 3 n:eters ner ~inute(1 1 feet per minute) 

vertical rise. 20 

Exhaust Emissions - In some cases the eniissions can be nigh because of 

cn excessive ventil~~ion rzte. As v~ith open top :,a,)or degre2sers the ventilaticn 

rate should not be much greater tlan 15 n3!min-rn2 (50 cfm/ft2) of airjsolvent 

interface. 2 1 
Waste Solvent Evaporation - Evaporation from waste solvent disposal is 

the sniall est emission from conveyorized degreasers. Most conveyori zed 

degreasers are designed to distill their own solvent. An external still is 

attached to the conveyorized degreaser so that used solvent can be constantly 

pumped out, distilled and returned. Thus, the wastes will usually 

consist only of still bottoms. Still, because of the high volume, waste solvent 

emissions fro^ conveyorized degreasers are significant, typically equal 1ing 

10 to 20 percent of the total emissions from a conveyorized degreaser. 22 

As was discussed earlier, the method of disposal of the still bottoms 

or undistilled waste solvent will determine the amount of solvent that 

evaporates into the atmosphere. 
REFERENCES 

1. T. J. Kearney, "Reply to J. C. Dollinger letter of September 3, 1976," 

letter of Cctober 1976. 

2. American Society for Testing and Materials (ASTM) Comrni ttee D-26, 

"Recornmended Practice for New Source Performance Standards to Control 

Solvent Metal Cleaning Emissions." 

3. Surprenant, K. S. and Richards, D. W. of Dow Chemical Company, "Study 

to Support New Source Performance Standards for Solvent Metal Cleaning 

Operations ," Uo1ur;e 2, Appendix C-72, prepared for Emission Stan~ards 

and Engineering Division (ESED) , under Contract # 68-02-1329, Task Ordei* 

#9, ;:ne 30, 1976. 

4. Information provided by K. S. Surprenant by telephone to J. C. iB~?lingei. 

EPA, Flarch 3, 1977. 

5. DON Cheml cai Company, "Modern Vapor Degrecsi ng ," operating 1;12vL!a-, tcrr G 

100-5185-72. 

ASTM, D-26., "Handbook of Vapor Degreasing," ASTM Special Tcc5r'c~' 

Fu~ii catlor. 31C A, Philadelphia, April, 1976. 

Detrex Chemical Ind., Inc., Detroit, "Todays' Concepts of Solvent 

Degreasi ng ,'I operating manual . C-8. r rr 

.:,I,, --LC, d~.>:L. 

I bi d. 

Surprenant , OD. Ci t. 

hericzn Society for Testing and Materials Op. Lit. 

Surprenant, Op. Cit. 

"Trip Report - Meeting of ASTM Cornittee D-26 on Halogenated Organic Solvents, 

Gatlinburn, Tenn.", EPA mernorandur~ from J. L. Shumaker to D. R. Patrick, 

June 30, 7977. 
3.0 EMISSION CONTROL TECHNOLOGY 

This chapter describes individual emi ssi on control devices appl i cab1 e 

to solvent degreasers, and then shows how these can be combined to form 

complete control systems. Estimates are also provided of the control 

efficiency (i .e. , percent emission reduction) of individual control devices 

along with a range of control efficiency for the complete control systems. 

It is important to keep in mind that optimum control systems will not 

be equivalent for each degreaser design or even each application of a 

particular design. All of the major devices discribed in this chapter will 

yield optimum control in certain instances; however, because degreaser 

designs and applications vary, one or more of these devices could be 

completely unsui table for a given degreaser. Processes must be evaluated 

individual ly to determine the optimum control system. The individual i ty 

of systems is such that control efficiencies estimated in this chapter are 

not directly comparable and should not be used to rate one device against 

another. They are given only as general levels of control which one could 

expect from appropriately applied technology. 

3.1 EMISSION CONTROL DEVICES 

3.1.1 Solvent Bath Emissions 

There are five main devices that can reduce emissions from the solvent 

bath: 

1. Improved cover, 

2. High freeboard, 
Information provided by Detrex Chemical Industries, Inc., Letter from 

L. Schlossberg to J. L. Shumaker, June 28, 1977. 

Surprenant , Op. Ci t. 

ASTM, D-26, Op. Cit. 

Bollinger, J. C., "Maximum Impact of NSPS on 1985 National Degreasing 

Emissions," December, 1975. 

Information provided by Bob Porter of Holl is Engineering Company, Nashua, 

N. H. by telephone to J. C. Bollinger, EPA, March 28, 1977. 

American Society, Op. Cit. 

ASTM, D-26, Op. Cit. 

Information, K. S. Surprenant, Op. Cit. 

Ibid. 
halogenated solvent. The water cover cannot be used in manv applications. however 

because the water may corrode the metal surface of the cleaned Parts or may 

cause chemi ca1 degradation of halogenated sol vent. 

Covers on cold cleaners which use flamnable solvents generally have a 

fusible link in the support arm. This link is designed to open if the solvent 

catches fire, thus a1 lowing the cover to close and smother the flames. 

Unfortunately, some designs requi re disassembly of the mechanism for normal 

closing of the cover. These designs cause unnecessary emissions and should be 

avoided. 

Not all cold cleaner designs include a soaking feature. Some of the 

smaller maintenance units are designed with an enclosed sump from which solvent 

is pumped to a sink for cleaning parts. The sink drains back to the sump, 

minimizing the time during which sol vent can evaporate. A1 though the solvent 

is contained, these units generally include a cover on the sink as a fire 

prevention feature. It is doubtful that closing this cover can effect a 

significant additional emission reducti on. 

Even though conveyorized degreasers are basically covered by design, 

additional cover related control can be achieved by minimizing the openings 

and covering the openings during shutdown hours. ASTM has recommended that 

there not be more than 6 inches (15 cm) clearance between the parts on the 

conveyor and the sides of the opening.' This clearance can be specifically 

defined as the average distance between the edge of the openings and the part, 

and termed the "average silhouette clearance." Average silhouette clearance 

can be appreciably less than 6 inches (15 cm) for parts that are not unusually 

large. EPA recommends an average silhouette clearance of 4 inches (10 cm) or 

10 percent of the opening's width. 
3. Refrigerated chi 1lers , 

4. Carbon adsorpti on, 

5. Safety switches. 

3.1.1.1 Improved Cover -

The cover is the single most important control device for open top vapor 

degreasers. Although covers are normally provided on open top degreasers 

as standard equipment, they can usually be made more easy to use, and hence 

more frequently used, if they are mechanically assisted, powered or automated. 

For vapor degreasers the cover should open and close in a horizontal 

motion, so that the ai r/vapor interface disturbance is minimized. These 

types of covers include roll type plastic covers, canvas curtains and 

guillotine covers. It is usually advantageous on larger open top vapor 

degreasers to power the cover. This may be done pneumatically or electrically, 

usually by manual control with an automatic cut off. The most advanced covering 

systems are automated in coordination with the hoist or conveyor. The cover 

can be designed so it wi 1 l close whi le the parts are being cleaned and dried. 

Thus, the cover would only be opened for a short period of time when the parts 

are actually entering or exiting the degreaser. This is further described in 

Section 3.1.3.1. 

On cold cleaners, covers are frequently mechanically assisted by means 

of spring loading or counterweighing. A pedal operated or powered system 

can make the cover even more convenient to use. For specific applications, 

two additional types of covers can be used; these are the submerged cover 

and the water cover. The submerged cover (comerci a1 ly termed "turbulence 

baffle") is a horizontal sheet of material submerged about two inches below 

the surface of the 1iquid solvent that is vigorously pump agitated. The 

water cover is simply a layer of water about two to four inches thick over a 
4 

The effectiveness of a down-time cover on conveyorized degreasers shoul d 

be significant, although it is difficult to quantify. One test found that 

about 18 percent of the total emissions was due to evaporation during down-time. 

It is expected that most of this loss could be eliminated by a down-time cover. 

3.1.1.2 High Freeboard -

The freeboard primarily serves to reduce drafts near the air/solvent 

interface. An acceptable freeboard height is usual ly determined by the freeboard 

ratio, the freeboard height divided by the width (not length) of the degreaser's 

ai r/sol vent area. 

Normally the freeboard ratio is 0.5-0.6 for the open top vapor degreasers, 

except for very volatile solvents, such as methylene chloride or fluorocarbon 

solvents, where a minimum freeboard ratio of 0.75 is used. In fact, the 

American Society for Testing and Materials has recomnended that a minimum 

freeboard ratio of 0.75 be an alternative control for open top degreasers using 

a1 1 sol vents. 5 

For an open top vapor degreaser that is idling (has no work load), the 

emission reduction from raising a freeboard ratio from 0.5 to 0.75 may typically 

be 25-30 percent. In fact, an increase in ratio from 0.5 to 1.0 may yield 

about a 50 percent reduction in emissions. These are EPA estimates based on 

a test by Dow Chemical .6 The total emission reduction due to the freeboard 

will generally be less for open top vapor degreasers under normal work load, 

because the freeboard is less effective in reducing the carry-out emissions 

than solvent bath emissions. 

The freeboard height seems to have little effect on cold cleaners using 

solvents with low volatilities, such as mineral spirits, but provides significant 

benefits for cold cleaners using higher volatility solvents, such as the 

ha1 ogenated ones. OSHA requires at least a 6 inch (15 cm) freeboard for 

cold cleaners. 7 
Covers can be easily made for the entrance and exit to the conveyorized 

degreaser so that they can be closed immediately after shutting down the 

degreaser. These covers can be made of any material that impedes drafts 

into the degreaser and should cover at least 80 to 90 percent of the 

opening. Closing these covers is most important during the hours imnedi ately 

after shutdown, because the hot solvent is cooling and evaporation continues. 

Even after the solvent sump has cooled, the down-time cover may be significantly 

effective for more volatile vapor degreasing solvents. 

A cover on an open top vapor degreaser has been shown to reduce total 

emissions by approximately 20-40 percent depending upon the frequency of 

2
 its use. 

It is impossible to estimate a single control efficiency for the cold 

cleaning cover, because the emission reduction varies too greatly with respect 

to the solvent volati 1 ity, draft velocity, freeboard ratio, operating temperature 

and agitation. However, it can be estimated that bath evaporation rate varies 

directly with the solvent volati 1 ity at operating temperature. A1 though a 

closed cover can nearly eliminate the bath evaporation, the cover can do nothing 

to reduce the carry-out or waste solvent emissions. Thus, a normally closed 

cover becomes effective only when bath evaporation accounts for an appreciable 

portion of the total emission. More specifically, when solvent volatility is 

moderate to high (approximately > 0.3 psi at 100°F (2.1 kPa at 38°~~), it is 

significantly effective to close the cover at all times when parts are not 

being cleaned manually in the cold cleaner. It is especially important that 

the cover be closed when the bath is agitated or heated. If none of these 

conditions apply, then the cover should at least be closed during long periods 

of cold cleaner disuse, such as during shutdown hours and idle periods > 112 hour. 3 
, Figure 3-1 

REFRIGERATED FREEBOARD CHILLER 

Primary 

Coils 

ter Jacket 
3.1.1.3 Refrigerated Chi 1 lers -

The vapors created within a vapor degreaser are prevented from overflowing 

the equipment by means of condenser coils and a freeboard water jacket. 

Refrigerated freeboard chillers add to this basic system a second set of 

condenser coils located slightly above the primary condenser coils of the 

degreaser (see Figure 3-1 ) . Functional ly , the primary condenser coi 1 s 

control the upper limit of the vapor zone. The refrigerated freeboard 

chilling coils on the other hand impede the diffusion of solvent vapors from 

the vapor zone into the work atmosphere by chilling the air immediately above 

the vapor zone and creating a cold air blanket. The cold air blanket results 

in a sharper temperature gradient. This reduces the mixing of air and solvent 

vapors by narrowing the air/vapor mixing zone. Finally, the chilling produces a 

stable inversion 1 a,yer which decreases the upward convection of sol vent lad~n air. 

Fkeboard chillers operat@ with refrigerant temperatures in the range of 

* 

-30 to 5OC. Although there is a patent on units which operate below O°C, 

most major manufacturers of vapor degreasing equipment offer both above 

and below freezing freeboard chi1 lers. 

The recomnended operating temperature for below freezina chi 11 ers is 

-30 to -25°C. Because of these low temperatures, designs must include a timed 

defrost cycle to remove the ice from the coils and restore the heat exchange 

efficiency. Although the liquid water formed during the defrost cycle is 

directed to the water separator, some water contamination of the vapor 

degreasi ng sol vents is not uncomnon. Water contarni nation of vapor degreasing 

solvents can have an adverse effect on water soluble stabilizer systems, 

a1 though major stabi 1 izer depletions from this are rare. Water, however, 

contributes to equipment corrosion and can diminish the working life of the 

equipment significantly. 

'US Patent 3,375,177 issued to AutoSonics Inc. , March 26, 1968, 

3- 6 
energy consumption may be too great when used on larger open top vapor degreasers. 

The refrigerated condenser coil offers portability of the open top vapor 

degreaser by excluding the need for plumbing to cool condenser coils with 

tap water. 

Tests have been performed for EPA on three below freezing refrigerated 

freeboard chillers. Emission reductions of 16, 43, and 62 percent were 

measured.1° The chiller which achieved only a 16 percent reduction in emissions 

was installed around 1968 and the design was not representative of present 

designs. This degreaser also had a low "uncontrolled" emission rate of 

0.14 lb/hr ft2, partly due to the use of a cover. The units which achieved 

43 and 62 percent reduction in emissions are thought to be more representative 

of present desi gns . 

EPA has not performed tests on above freezing freeboard chillers or 

refrigerated condensing coi 7 s. However, tests are planned whi ch should 

he1p quantify the effectiveness of these controls. 

Chillers are not normally used on cold cleaners. While it is certain 

that a chiller would reduce emissions, especially from units using the more 

volatile solvents, this control is generally too expensive for a normal cold 

cleaner. A chiller on a cold cleaner should have about the same effectiveness 

as a normally closed cover, but it would cost considerably more. In fact, a 

chiller could well cost more than the cold cleaner itself. Still, some 

manufacturing cold cleaners with unusually high emission rates could find 

a chi 11 er appropri ate. 

3.1.1.4 Carbon Adsorption -

Carbon adsorption systems are widely used to capture solvent emissions 

from metal cleaning operations. On appropriate degreasing processes, these 

devices can achieve high levels of emission control. Equipment design and 

operation (as illustrated in Figures 3-2, 3-3, and 3-4) are fairly well 

3-9 
Refrigerated freeboard chi 1 lers are normally sized by specifying 

the cooling capacity per length of perimeter. The above freezing refrigerated 

freeboard chiller is normally designed to achieve a minimum of 500 Btu/hr - (865 W/m.OK) cooling capacity per foot of air/vapor interface perimeter, while 

the below freezing refrigerated freeboard chiller is normally designed to 

the following specifications: 

Minimum Cooling Capacity 

Degreaser Width (Btu/hr ft of perimeter) 

< 3.5 ft. (1.1 m) 

> 3.5 ft. (1.1 m) 300 

> 6 ft. (1.8 m) 400 

> 8 ft. (2.4 m) 500 

> 10 ft. (3.0 m) 600 rr 

Normally each pass of finned cooling coil is expected to remove 100 Btu/hr 

ft (1 73 ~/n OK). The previ ous speci f i cati ons are typi cal desi gn standards

used by manufacturers of chillers. €PA test data indicate that these design 

standards wi 11 provide satisfactory emission control, but at present data are 

insufficient to confirm that they yield optimum emission control. 

In addition to these, a third type of refrigerated chiller, known as 

the refrigerated condenser coil, is available. Refrigerated condenser coils 

do not provide an extra set of chi 11 ing coi 1s as the freeboard chi 1 lers do, 

but replace the primary condenser coi 1s. If the coolant in the condenser 

coi 1s is refrigerated enough, it wi 11 create a layer of cold air above the 

air/vapor interface. DuPont and Rucker Ultrasonics have recomnended that the 

cooling rate of refrigerated condenser coils be equal to 100-120 percent of 

the heat input rate in the boiling sump, in order to give optimum emission 

i 

control .' The refrigerated condenser coils are normally used only on small 

open top vapor degreasers (especially with fluorocarbon solvent), because 

3-8 

Figure 3-3 

ADSORPTION CYCLE 

t-Laden 

nlet 

Activated Carbon 

Bed 

-Clean Air 

Exhaust 
standardi zed and described in detai 1 in general 1 i terature, in the Dow 

12 ~e~ort"and in the report by JACA Corporation. 

A well designed and maintained carbon adsorption system will normally 

capture in excess of 95 percent of the organic input to the bed. Carbon 

adsorption systems for solvent metal cleaning normally wi 11 achieve about 

40-65 percent reducti on of the total solvent emission. l3 One reason for 

the difference between the theoreti'cal and actual is. that tk ventilation apparatus 

of the control system cannot capture all of the solvent vapors and deliver 

them to the adsorption bed. As has been discussed earlier, major loss 

areas are drag-out on parts, leaks, spills, and disposal of waste solvent, none 

of which are greatly affected by the ventilation system. Improved ventilation 

design can increase an adsorber ' s overall emi ssi on control efficiency. 

Higher venti lati on rate alone, however, wi 11 not necessarily be advantageous, 

since increased turbulence could disrupt the airlvapor interface causing an 

increase in emissions, all of which would not be captured by the collection 

systems. The effectiveness of the ventilation system can also be improved 

through use of drying tunnels and other devices which decrease losses due 

to dragout. 

Poor operation has been found to decrease the control efficiency of 

carbon adsorption systems. Examples are dampers that do not open and close 

properly, use of carbon that does not meet specifications, poor timing of 

the desorption cycles, and excessive inlet flow rates. Desorption cycles 

must be frequent enough to prevent breakthrough of the carbon beds, but not 

so frequent as to cause excessive energy waste. The degreaser's airlvapor 

interface may be disturbed as a result of excessive adsorber inlet flow. This 

can increase losses due to low adsorber inlet collection efficiency. Good 
Figure 3-4 

DESORPTION CYCLE 

Condenser 

vated 

on Bec 

Recovered 

Sol vent 

Steam Inlet U 
i 

operating practice and proper maintenance will eliminate all of the above 

problems. 

Carbon adsorption systems can effect the highest achievable level of 

emission control for many degreasing operations. Its positive aspects are 

we1 1 known. There are, however, a few negative aspects that should be 

mentioned. F irs t, where solvent mixtures are used, the col 1ected sol vent 

emissions will be richer in the more volatile components. Thus, the 

recovered solvent mixture is rarely identical to that used in the cleaning 

system. Second, there are solvent components that are water soluble. Examples 

are acetone or ethyl alcohol used as co-solvents with t~~chlorotrifluoroethaneand 

stabilizers added to tllany sol vents to inhi bit decomposition. The yateisoluble components wi 11 be selectively extracted by the stearn during the desorpti on 

process. In these cases, fresh solvent, stabilizers and/or co-solvents must 

be added to the recovered solvent before it is reused. 

Tests performed on carbon adsorption systems control1 ing an open top 

vapor degreaser and a conveyorized non-boiling degreaser, measured 60 and 

65 percent emission reduction respectively.14 These levels of control are 

typical of properly designed ,adjus ted and maintained adsorption sys tems on 

degreasing operations which are suitable for this type of control. Three 

other carbon adsorption systems were tested and found to have low control 

efficiencies. Two of these systems achieved 21 percent and 25 percent emission 

reductions. A third was found to actually increase emissions by 8 percent. 15 

These tests exernpl ify the need for proper application, design, operation, 

and maintenance of carbon adsorption sys tems. 

3.1.1.5 Safety Switches -

Safety switches are devices used on vapor degreasers to prevent emissions 

during malfunctions and abnormal operation. The five main types of safety 
swi tches are : 

1. Vapor level control thermostat, 

2. Condenser water flow switch and thermostat, 

3. Sump thermostat, 

4. Solvent level control, 

5. Spray safety switch. 

The first four safety switches listed above turn off the sump heat while the 

fifth turns off the spray. 

The most important safety switch is the vapor level control thermostat. 

This device is activated when solvent vapor zone rises above the designed 

operating level. This can occur if the coolant flow is interrupted, for 

example. When the hot vapors are sensed, the sump heater is turned off thus 

minimizing vapor escape. This thermostat should be a manual reset type for 

manually operated degreasers. For conveyorized degreasers, the vapor level 

control thermostat should activate an alarm system. These controls should 

be checked frequently. 

The condenser water flow switch and thermostat turn off the sump heat 

when either the condenser water stops circulating or the condenser water becomes 

warmer than specified. If the condenser water flow switch and thermostat is 

properly adjusted, then it will serve as a back-up for the safety vapor 

thermostat and also assure efficient operation of the condenser coi 1s. 

In summer months, the cooling water for condensing coils often becomes too 

warm. In this case, the thermostats in a condenser water flow switch can 

signal a need for improvement, such as increasing the water flow rate. This 

problem occurred during a test performed for EPA. 16 

As oils, greases and other contaminants build up in the solvent, the 

boiling point of the mixture increases. Both the sump thermostat and solvent 
level control prevent the sump from becoming too hot, thus causing solvent 

decomposition. The sump thermostat cuts off the heat when the sump temperature 

rises si gni f i cantly above the solvent's boi 1 ing point. The solvent level 

control turns off the heat when the liquid level of the boiling sump drops 

down to the height of the sump heater coi 1s. Without these controls, 

excessive heat could decompose the sol vent, emitting such things as hydrochloric 

aci d . 

The spray safety switch is not used as often as the other safety switches, 

but it can offer a significant benefit. Specifically, if the vapor level 

drops below a speci f ied level , then the pump for the spray application wi 11 

be cut off until the normal vapor level is resumed. Thus, the spray safety 

switch prevents spraying above the vapor level which causes excessive 

17 emi ssi ons . 

The effectiveness of the five safety switches cannot be quantified 

because thei r operati on results from poor degreaser maintenance and use. 

Nevertheless, considering the fact that vapor degreasers do not always 

receive proper attention and maintenance, it is expected that the safety 

switches wi 11 provide a significant reduction in emissions for typical vapor 

degreasing operations. 

3.1.2 Controls to Minimize Carry-out 

Carry-out emissions are the solvent emissions that result when clean 

parts sti 11 containing liquids or vapors are extracted from the vapor degreaser. 

As described in chapter 2, good operating practices are the primary method of 

reducing carry-out emissions. Furthermore, there are devices that can help 

minimize the carry-out from cold cleaners and conveyorized degreasers, but 

not generally from open top vapor degreasers. 
The main control device for carry-out emissions from cold cleaners is 

a simple drainage facility. The two types of drainage facilities are the 

external and internal drainage racks (or shelves). The external drainage rack 

is attached to the side of the cold cleaner at the top. The liquid solvent 

from the cleaned parts drains into a trough and is returned to the cold cleaning 

bath. This control is inexpensive and easi ly retrofitted. An internal 

drainage facility is located beneath the cover. It may be a basket that 

is suspended over the solvent bath, or a shelf from which the solvent drains. 

Particularly with solvents of higher volatilities (i.e. , much greater than 

that of mineral spirits), an internal drainage facility can prevent a 

significant sol vent emi ssion. The internal drainage faci 1 i ty sometimes cannot 

be reasonably retrofitted, because there may not be enough room inside the 

cold cleaner to drain parts while cleaning other parts. 

The main control devices for carry-out emissions from conveyori zed 

degreasers are a drying tunnel and rotating baskets. A drying tunnel is 

simply an extension from the exit of the conveyorized degreaser. This tunnel 

extension gives cleaned parts more time to dry completely. The drying tunnel 

should work particularly we1 1 in combination with carbon adsorption. Drying 

tunnels can be retrofitted, if there is adequate space. Rotating baskets 

may be used on cross-rod degreasers and ferris wheel degreasers. A rotating 

basket is a perforated cylinder containing parts to be cleaned that is slowly 

rotated through the cleaning system, so that the parts cannot trap liquid 

sol vent. Rotating baskets are designed into the conveyori zed sys tem and hence 

are not easily retrofitted. 

Conveyors themselves can contribute to carry-out emissions. Some 

designs cause less emissions than others. In general, these emissions are 

directly proportional to the surface area entering and leaving the cleaning 
zone. One design, uses small pushers to move parts along fixed rods which 

support the work. This design is advertised to carry-out 70 percent less 

solvent than conventi onal wire mesh conveyors. 

The effectiveness of control devi ces that he1 p mi nimi ze carry-out 

emissions cannot be quantified. The amount of carry-out depends too much 

on the type of work loads (shape and crevices) and the qua1 ity of operation. 

Nevertheless, it is obvious that if the exiting cleaning parts visibly show 

1 iqui d sol vent, then carry-out emissions wi 11 be substanti a1 . 

3.1.3 Controls for Solvent Bath and Carry-out Emissions Combined 

Two contr;? systems reducc both sc?*;e:t 53th 2nd carry-out emissions. 

They are the automated cover-conveyor system and a refrigeration condensation 

system. Both systems are relatively new designs and infrequently used in 

practice. They are somewhat complex and expensive in relation to most other 

control devi ces. 

3.1.3.1 Automated Cover-Conveyor Sys tem -

The purpose of an automated cover-conveyor system is to close the 

cover of an open top vapor degreaser when parts are being cleaned and 

dried. Thus, the cover is open only for the short period of time when dry 

parts are actually entering or exiting. (It is possible to use this system 

on a cold cleaner but the solvent volatility and losses would generally 

have to be very high to justify the expense of such a system. ) The automated 

cover must be capable of closing while the part is inside the degreaser. If 

the part is conveyed by means of a cable and hoist, then the cover can 

close horizontally and be split into two parts so that it closes at the center 

where the cable is located. If the parts are conveyed by means of a shelf 

that automatically lowers and rises, then the vapor degreaser can be 

covered by a permanent enclosure wi th a verti cal door, (See Figure 3-5). 

Automated conveyor sys terns incl ude adj us tab1 e timing del ays for cl eani ng 

and drying and automatic cut-offs to position the work load for cooking and 

drying. 

Because emissions could occur only for the short period of time when 

dry parts are entering or exiting the automated degreaser, it is expected 

that an automated cover-conveyor system would provide highly effective 

control . 

3.1.3.2 Refrigeration Condensation -

Direct condensation of solvent vapors from exhaust air streams is a 

possible a1 though perhaps difficult means of recovering solvent. Sulllr 

insight into the problem is gained by examining Figure 3-6. 20 

Condensation wi 11 occur when an ai r/vapor stream is refrigerated to 

a temperature where the solvent's equilibrium vapor pressure is less than 

its actual vapor pressure. The actual vapor pressure is calculated by 

mu1 tiplying the percent solvent vapor concentration (by volume) by the total 

pressure (usual ly atmospheric). For example, 1000 ppm of perch1 oroethylene 

at atmospheric pressure yields an actual vapor pressure of 0.76 mm Hg 

(0.1 percent concentration multiplied by 760 m Hg). Extrapolating from 

the graph, 0.76 mm Hg intersects curve #9 at -25OC; thus, condensation 

occurs below -25°C for perchloroethylene at 1000 ppm and 1 atmosphere. 

A1 though sol vent concentrations may reach 1000 ppm momentarily ,the 

average concentration of chlorinated solvent vapors from typical operations 

is about 300 ppm (0.23 mi 11 irneters HCJ) . Consequently, direct cond~nsati on 

of perchloroethylene would not usually occur until the temperature of the 

air/vapor stream was reduced to at least -40'~. 

There are two major problems with refrigerati on condensation. First, 

at these low temperatures, ice forms rapidly on the hkat exchange surfaces, 

reducing the heat exchange efficiency. The ice formation also requires the remova 

3-20 

Figure 3-6. Vapor Pressures ot jeveral Solvents 
of a large amount of heat (1300 Btu's per pound) which will add significantly 

to the cost of this control, Second, when condensation occurs a fine mist of 

liquid solvent is formed. The problem is in removing this mist from the air 

stream. 

This analysis indicates that it would be difficult to control emissions 

from degreasers with refrigeration condensation, However, this rests on two 

assumptions: (1 ) 1 atmosphere pressure is maintained and (2) vapors cannot 

be coll ected in higher concentrations, Still , this does not preclude its 

successful use. An example is one design which was reported after the initial 

EPA test program had been completed. The equipment manufacturer, Autosonics 

Inc., reported successful emission control using a prototype of their desig!~, 

called the "Zero-Emission" vapor degreaser. This system employs refrigeration 

condensation along with carbon adsorption and is reported to be able to 

capture solvent vapors with unusually high efficiency. EPA tests on this 

degreaser are planned. 

3.1.4 Control of Waste Solvent Evaporation 

3.1,4,1 Current Practices -

Emissions from waste solvent occur through a number of diverse routes, 

none of which can be easily monitored or quantified. Based on the 1 imi ted 

information currently available (see Appendix B.5), it is estimated that 

about 280 thousand metric tons of waste solvent were disposed of from metal 

degreasing operations in 1974. This is approximately one-third of the total 

metal degreasing emissions, 

Most of this waste is disposed of in a manner such that it can evaporate 

into the atmosphere. A large fraction is indiscriminately dumped into 

drains or onto the grounds surrounding the using facility. Some waste 

solvent is stored in open containers and evaporates. A small amount of waste 

solvent finds its way to municipal or chemical landfills that make no 
attempt to encapsulate the solvent. Some larger companies have used 

deep well injection, but overall this is considered an insignificant disposal 

route for waste solvent from degreasing. It has been estimated that these 

four disposal routes account for %35 percent of the total waste solvent 

1 oad. 

It is convenient for automotive maintenance facilities to dispose of 

their waste sol vent a1 ong wi th their waste crankcase oi 1. Perhaps as much 

as 15 percent of the total waste solvent load (or s33 percent of the 

waste sol vent from maintenance cold cleaners) enters this route. Crankcase 

oi 1 is reprocessed, rerefined, used for dust control on unpaved roads or handled 

in other ways, none of which pay significant attention to the solvent 

fraction. 

Properly controlled incineration is one of the few disposal routes 

which does not result in organic emissions to the atmosphere. However, 

only a small fraction (-5 percent) of waste solvent is believed to be disposed 

of in this manner. 

Solvent reclamation is the most environmentally acceptable route for 

waste solvent. It is believed that -45 percent of the waste solvent load 

is being reclaimed through di sti 11 ation. 22923 Primarily , ha1 ogenaied 

solvents are distilled; petroleum related solvents, such as mineral spirits, 

are more difficult and less profitable to distill, because such solvents 

are flammable and inexpensive, compared to halogenated sol vents. 

3.1 .4.2 Recomnended Practi ces -

Reclamation Services - Reclamation services collect waste solvent, disti 11 

it, and return the reclaimed portion to the solvent user. Charges vary but 

are roughly equal to one half the market value of the solvent. In industrial 

areas where large numbers of users are present, solvent scavenging and 

reclamation is being practiced profitably. In rural areas, where users are 
1 

separated by large distances, collection and transportation is a 1imi ting 

factor. HoWever, sui tabl, collection systems could be devifed and reclamation 

service could be expanded beyond the industri a1 areas. For example, it would 

be possible for the rural user to store waste solvent in sealed containers 

unti 1 sufficient volume is acquired to make collection economical. 

Another a1 ternative is offered by the Safety Kleen Corporation. This 

firm provides a service of supplying both the solvent and cold cleaning 

equipknt to usei-s. The solvent used is periodically collected and replaced 

with fresh solvent by the company and the used solvent is distilled at central 

locations. The firm operates in industrial areas throughout the U.S. 

In-House Reclamation - Many large users practice in-house reclamation. 

In vapor degreasing, the use of stills is fairly comnon. For instance, 

nearly a11 conveyorized vapor degreasers and 1 arge open top degreasers are 

equipped wi th s ti11s. (see Figure 3-7). These s ti11s have been cus tomari ly 

used because they reduce the maintenance cost of cl eani ng the vapor degreas ing 

system, enable the sys tern to remove soi 1s col lected wi thout interrupting 

the cleaning process and recover valuable quantities of solvent. The Dow 

Report estimated that the total yearly cost of in-house reclamation of 

chlorinated solvents can be recovered from the first 350 gallons distilled. 

Nonchl ori nated sol vents, because of thei r f1 amnabi 1 ity and 1 ower recovery 

value, would require 6 to 12 times this quantity. 

Bottoms from all disttllation columns are of a hazardous nature, 

containing metals, sludge, residual solvent, etc. They must be disposed 

of properly in chemical landfills or preferably through a properly controlled 

high temperature incineration facility. 

Each solvent class exhibits its own pecul lar problems in disti 1 lation. 

Chlorinated solvents are part1 a1 ly stripped of their stabi 1 izers during 

disti ilation. These must be replaced to avoid chemical decom7-:i tion of 

the recovered solver^ t. Nonchl ori nated sol vents are quite flammab' and 

require equipment designed to prevent fires and explor'ons. Solvent blends 

usually consist of solvents of different boiling points; thus, the solvent 

initial 1y recovered has a higher portion o - lower boiling poini; solvents. 

Certain contaminates can also greatly increase the difficulty of disti 11 ing 

any solvent. For example, azeotropes can form betdeen contaminates and sol~~.?nts 

during distillation, making separatf on difficult. Also, adverse chemical 

reactions can occur. For these reasons disti 11 ation service companies 

general ly analyze waste solvent. The company using in-house disti 11ation 

can often eliminate analysis and avoid many of the problems encountered by 

services which distil 1 a mixture of solvents from different users, because the 

solvents and the contaminants are known. 

Direct Incineration - Direct incineration in a properly control led -.- P. -

faci 1 ity is another envi ronrnental ly acceptable disposal route for waste 

solvent. Incineration does not, however, produce a useable product and 

often requi res significant amounts of supplementary fuel. For these 

reasons, it is not as attractive as reclamation. Nonchlorinated solvents are 

fuel oil grade waste and after simple filtration of hazardous contaminates 

could provide the heat value necessary for incineration of chlorinated 

compounds. However, their fuel value will be considerably less than their 

solvent value. 

There are approximately 25 to 50 faci I ities in the UnS ted States capable 

of acce~tahly incineraticg chlorinated solvents. Such facilities require high 

t~n!peratures ( J1230"Sj, ;dfficient rx!der.ce tine (about L seconds ), and 

sop+ :s ticate:: e~h39:t gas s i eani 73 equ i p~nt tu rerzove ha1 qsnated compoucds 

[primal ily HCl:, riarticulates, 2nd other csntamindnts- Ca~i tal investment to 
Luiid t: is LIC~~f ;ncinera~~rir c-$;I t,car;t [I.. t~ 5 ;7, 10 (o . .,dr 

6 gailo:! cf :2cte per ~in~te capacity). ~Cpe~~ti-,, ccstr, hc /e ~eeFect .rated 

24 at lecc th~n2Q/lt; ~f s;iw-it iri:il;c?ratcd. 

,Ilt:n:ca; Lacdf?: i- - ;tllr+c-ni-.ik trier: are rPclrica1 iand'i"r ;.r ica~c1 ' 3 tion 

pro.zer; ?s appraved 12;- th* disixza' c9waste zo'venf., hour;^.!.. c - c
- ' i : , :hi ; 

- Rannsr could result iii losr of vclat~leorganfc:, ~hesef ciliti~;-2 :rt~ent 

emissions if extrm~Lare is 'aKcn to e-imiraz~c:apcraf,'s.~ ar;a pefi i-q. 

One method has been to seal the haste solvent in lined drum and surb ;und the 

drums FS th 4 ic 23 ft, of pzckej :lay. No testirg has beon don^ tc; ,_-rn 

that even this method will contrcl vrganic emissions. Ir is be: ieved tndt 

most chemical landfjlls are not ddequate for the disposal of waste sclvm;t. 

It is not the purpose of this report to evaluate waste solvent disposa; 

facilities in depth, rather only to show that they are available, even 

though the degree of their excessibilit; varies geograpnica-iy. EFc's (: ?f 

Sol .'c-~ C id kite Managemen: Programs is currently preparing rcgulat inns. 

the Resource Conservation and Recovery Act of 1976, to cover transportacion, 

-8 storage, treatment and disposcl of hazardcliz waste. I11ece recu iat roils are 

targeted for promigatiirn in dprf 1 94: i97E and hcp&ul ly wi! 1 apply ' . -': 

waste ~olventsfrm d~greasing. 

3.1.5 Cther Control Devices 

Two other control devices could conceptually be used to reduce solvent 

bath emi ss.i ons : incineration and 1iquid absorption. Generai ly , incineration 

appears to be too expensive and energy intensive, and liquid absorption presents 

speci a1 technical problems and could even cause increased atmospher:~ emissions. 
3.1.5.1 Ipsi nersti OP -

incineration ha; been used for many years to control emissions of organics 

to the atmosphere. For degreasing operations, it could be applied most 

easily to sys terns using petroleum hydrocarbons and oxygenated sol vents whi ch 

readi ly combus i to carbon dioxide and water. App! ication to sys te~ns using 

halogenated hydrocarbons would be more difficult. A1 though halogenated 

hydrocarbons are non-f 1arrnnabl e under normal condi ti ons , they can be pyrolyzed 

at temperatures ;n the inci nerafi on range. The pyrolyti c decomposi ti on of 

cblorindted hydrocarbons, for example, wi 11 release chlorine, hydrochloric 

6 :id, ad phosgene depending upon the conditions of oxidation. These product; 

would have to be removed from the off-gas stream of the incinerator using 

sophisticated gas cleaning equi~nent before exhausting to the atmosphere. 

75: cost of incineration could also be high. First, capital requirements 

are generally large, particularly in comparison to the relatively low zest of 

most degreasers. F~rthermore, costs would be significantly increased with 

the addition of gas cleaning equipment, were that needed. Next, solvent 

c~ncentrations in exhast streams are frequently below the range requi red 

to sustain combusti on; thus, supplemental fuel would be required. Scarce fuel 

resources would make this a limiting factor. 

3.1.5.2 Liquid Absorption -

Liquid absorption is a well known process that has been investigated for 

use in solvent metal cleaning. For example, tri chloroethylene vapors in air 

could he substan ti a1 ly reduced by absorption in mineral o i 1. However, at an 
Chi1 ling the absorbing fluid would reduce its concentration in the 

exhaust air. However, cooling to a temperature below 0°C (32°F) would cause 

ice formation in the column since water is insoluble in mineral oil. Although 

this could be avoided by prerefrigeration of the air stream, the use of 

refrigeration would greatly increase energy consumption. Finally, the energy 

requi regent for recovering the solvent from the mineral oil is great. Thus, 

it appears that this method of emission control is impractical except for the 

recovery of (1 ) high concentrations of solvent vapors in air, (2) very valuable 

vapors or (3) highly toxic chemical vapors. 19 

3.2 COMPLETE CONTROL SYSTEMS 

A complete emission control system utilizes both contrcl equipment and 

~3erating procedures. Although controls can be combined in many ways to form 

3~1ydifferent control systems, twc 9as-i~ control syzterz for each type 

-:gl :c3er are presented here. General ly , control system A consi s ts of proper 

czerating practices and simple, inexpensive control equipment. Control 

-ystc~;0 consists of syste~A plus other devices that increase the effectiveness 

f xrtxl. The details of contml system A or B can be modified to arrive 

- love1 of contrcl needed. 

T?e smission control efficiency of reasonably we1 1 designed and maintained 

cz-troi systems is estimated from the present test data base. Control systems 

wh-ch are seriously defective are not uncomnon. A few such systems were 

even recomended unintentionally by contrcl system vendors to EPA as being 

exemplary; it required close inspection and sometimes etnission measurements 

to discover that the systems were defective. 
3.2.1 Cold Cleaning Control Systems 

The most important emission control for cold cleaners is the controS 

of waste solvent. The waste solvent needs to be reclaimed or disposed of so 

that a minimurn evaporates into the stnosphere. Next in importance are the 

operating practices of closing the cover and draining cleaned parts. Severa7 

other control techniques becme significant only in a small fraction of 

appl ications. The control devices and operating practi ces for control 

systems A and B are summarized in Table 3-1. 

There is not a 1arge difference in effect between sys tern A and 6, 

because most of tne cold cleaning emissions iire controiyeci in systern A. if 

the requirements qf systm A were followed conscienti~usly by nearly a1' 

of the cold cleaning operators, there would be little need for the acidit1 .,:I;1 

sys tem B requi remen ts. However, because cold cleani n~ cqerators can tend 

to be lax in keeping the cwzr closed, equipment requirements #1 and #4 in 

systarn R are added. Sinilarly, the nodifications for #2 and the equipzwt 

requirements in #3 v:ouid effect significant emiszion reductions in a few 

appl i cati ons. 

Although t7e effectiveness of the control systems depends greatly on 

the qua7 i ty of operation, average cases have been approximated, (see Appendix B. 1j 

Syste~A could reduce cold cleaning emissions by 50 (90) percent 

and system B may reduce it b~y53 (+20) - percent. The lower end of the ratiqe 

rqresents thz emission reductim projected for poor compliance, and the nigher 

end represents excellent compliance. As can be readily seen from these estimates, 

the expected benefit from system B is only slightly better than that for 

system A for an average cold cleaner, assuming low volatility 

solvents. This difference is small because the additional devices required 

in system B generally control only bath evaporation, which represents about 
TABLE 3-1. CONTROL SYSTEMS FOR COLD CLEANING 

Control Syrtm A 

Control Equipment: 

1. Cover 

2. Facility for draining cleaned parts 

3. Permanent. conspfcuous label, surmariz:ng the operating requirements 

Operating Requirements: 

1. Do not dispose of waste solvent or transfer it to another part:/, 

such that greater th$n 20 percent of the waste (by weight) can waporate 

into the atmosDhe?e. Store waste. solvent on.lv in covered containers. 

2. Close degreaser cGver whenever not handling parts in the cleaner. 

3. Drain cleaned parts for at least 15 seconds or until dripping ceases. 

Control System 8 

Control Equipment: 

1. Cover: Same as in System A, except if (a) solvenf volatility is 

Tre2 ter than 2 kPa (15 m Hg or 0.3 psi) veasured at 28°C ,lOO°F\ ,** 

b) soivent is agitated, or (c) solvent is heated. then the cover must 

be designed so :hat 1: car be easilv 3pera:ed with one hand. 'Covers for 

;drqer Geqreasers may recuire mechanicai assistance. by ;orin5 !oadin~, 

raunterweiqhti nq or lowered svstems. ! 

2. 3rainage facility: Same as in bystem h, except that if so:vent 

volatility is greater than about 4.3 kPa (32 mn Hp or 0.6 psi ) measured at 

38'C (lOO°F), then the drainage facility muzt be iqternal, SG that parts ?re 

enclosed under the cover while draining. The drainage facility my be 

externai for aoplications where an internal type cannot fit lnto the cleaninq 

svstem. 

3. Label : Same as in System A 

3. If used, the so:vent spray must be a solid, fluid stream (not ti 

fine. atomized or shower tvoe soravl and at a Pressure which does not czuse 

excessive splashing. 

5. Major control device for highly volatile solvents: If the solvent 

volatility is > 4.3 kPa (33 m Hg or 0.6 psi measured at 38°C (13C°F), 3r 

jf solvent is heated above 50°C (12O0F), then one of the following control 

devices must be used: 

a. Freehoard that gives a freeboard ratiof** 20.7 

b. Water cover (solvent must be insoluble in and heavier than water) 

c. Other systems of equivalent control, such as a refrigerated chiller 

or carbon adsorption. 

Same as in System A 

%ater and sol id waste regulations must a1 so be cmpl ied with. 

**Generally solvents consisting primarily of mineral spirits (Stoddard) have 

volatilities .2 kPa. 

***Freeboard ratio is defined as the freeboard height divided by the 

width of the degreaser. 
-- 

-- -- 

20 to 30 perc-nt of the total emission from an average cold cleaner. For 

cold cleaners with high volatility solvents, bath evaporatisn may 

contribute ~50percent of the total emission; tt is estimated that system 6 

may achieve 69 (220) percent control efficiency, whereas system A might 

experience only 55 (+20) - percent control. 

3.2.2 -Control Systems for Open Tcp Vapor Degreasin9 

The basic elements of a control system for 37en top vapor degreasers 

zre proper operating practices and use of control equipment. There are 

about ten main operating practices. The control eqgipment includes a cover, 

safe", y;;i teks 3rd a major control device, ef ther h? gh freebaard, refri yerated 

c$ii ler, enclosed design or carbon adsorption. Two control systems for open 

top vapor degreasers are out1 ined in Table 3-2. 

The vapor level thermostat is not included because it is aiready required 

by OSHA on "o?en surface vapor degreasi ng tanks. " -he sump thermostat and 

solvent level cmtrol are used primarily to prevent sc!vec5 ieyad3tion and 

protect the equipment and thus are also not included here. The emizsicn 

reduction by these controls is a secondary effect in any event. The two . . 

safety switches presented serve primarily to reduce vapor solvent emissions. 

System A may reduce open top vapor degreasing emissions by 45 (t15) percent, 

and system E my reduce them by 60 (+15) percent. For an average size 

open top vapor degreaser, system A and S would reduce emissions from 9.5 rn 

tons/year dowr! to about 5.0 and 3.8 rn tons/year, respectively. It is clear that 

systein B is appreciably more effective than system A. 

3.2.3 -Control Systems for Convgorized gegreasers 

2mtrol devi ces tend to work most effecti vely on conveyorized degreasers , 

mainly beca~;e they are enclosed. Since these cmtrol devices can usually 

result in solvent savings, they often will net an annualized profit. 
TABLE 3-2. COMPLETE CONTROL SYSTEMS FOR OPEN TOP VAPOR DEGREASERS 

. Control System A 

Control Equipment: 

1. Cover that can be opened and closed easily without disturbing the 

vapor zone. 

Operating Requirements : 

1. Keep cover closed at all times except when processing work loads 

through the degreaser. 

2. Minimize solvent carry-out by the followlng measures: 

a. Rack parts to allow full drainage. 

b. Move parts in and out of the degreaser at less than 3.3 m/sec (11 ft/min) 

c. Degrease the work load in the vapor zone at least 30 sw. or until 

condensation ceases. 

d. Tip out any pools of solvent on the cleaned parts before removal. 

e. Allow parts to dry within the degreaser for at least 15 sec. or until 

visually dry. 

3. Do not degrease porous or absorbent materials, such as cloth, leather, 

wood or rope. 

4. Work loads should not occupy more than half of the degreaser's open 

top area. 

5. The vapor level should not drop more than 10 cm (4 in) when the - work load enters the vapor zone. 

6. Never spray above the vapor level. 

7. Repair solvent leaks imnediately, or shutdown the degreaser. 

8. Do not dispose of w? solvent or transfer it to another party 

such that greater than 20 percent of the waste (by weight) will 

evaporate into the atmosphere. Store waste solvent only in closed containers. 

9. Exhaust ventilation should not exceed 20 m3/min per nz (65 cfm per ft2) 

of degreaser open area, unless necessary to meet OSHA requirements. Ventilation 

fans should not be used near the degreaser opening. 

10. Water should not be visually detectable in solvent exiting the water 

separator. 

Contro: System B 

Control Equipment: 

1 . Cover (same as in system A]. 

2. Safety witches 

a. Condenser flow switch ana tnennostat - (snuts off sump neat if condenser 

coolant is either not circulating or too warm). 

b. Spray safety switch - (shuts off spray pump if the vapor level drops 

excessively. about 10 cm (4 in). 

3. Major Control Device: 

Either: a. Freeboar9 ratio reater than or equal to 0.75, and if the 

degreaser opening is > 1 m (10 ft9), the cover must be powered, 

b. Refrigerated chiller, 

c. Enclosed design (cover or door opens only when the dry part 

is actually entering or exiting the degreaser.), 

d. Carbon adsorption system, with ventilation ,15 m3/min per mZ 

(50 cfm/ft2) of airlvapor area (when cover is open), and exhaustinq -25 Dpm 

solvent averaged over one complete adsorption cycle, or 

e. Control svstem. demonstrated to have control efficiency, 

equivalent to or better than any Of the above. 

4. Permancnt, conspicuous label. sumnarizing operating procedures ff1 to 16. 

Operating Requirements , 

Same as in System b 
Two recommended control systems for conveyorized degreasers are shown in 

Table 3-3. Control system A requires only proper operating procedures which 

can be implemented, in most cases, without large capital expenditures. Control 

system B, on the other hand, requires a major control device. 

Major control devices can provide effective and economical control for 

conveyorized degreasers. A refrigerated chiller will tend to have a high 

control efficiency, because room drafts generally do not disturb the cold air 

blanket. A carhon adsorber also tends to yield a high control efficiency, 

because collection systems are more effective and inlet streams contain 

hi gher sol vent concentrations, for conveyorized degreasers than for open top 

vapor degreasers. 

Small scale conveyorized degreasing appl ications can resul t in significantly 

high annualized costs from using a major control device. Consequently, many 

operators may be motivated to use the less expensive open top vapor degreaser 

in place of a conveyorized one, even though more solvent is emitted for an 

equivalent work load. Thus, it is reasonable to exempt conveyorized degreasers wit 

less than 2.0 m2 of air/vapor interface from requirement of a major control device. 

The remaining three control devices recommended in system B should entail 

nominal expense in relation to their potential solvent savings. Because of 

the wide diversi ty of appl icati ons for conveyori zed degreasi ng , there may be 

a few applications where the drying tunnel or a minimized opening may be 

impractical; thus, occasional exceptions may have to be made for these two 

requirements. For example, a plant might not have enough space available to 

permit use of a drying tunnel; also, hanging parts may occasionally swing 

from a conveyor 1 ine more than the clearance a1 lowed by the control requirement. 

The control efficiency for system A is estimated at 25 (+5) - percent and 

for system B, 60 (+lo) - percent. Emissions from a typical conveyorized degreaser 
TABLE 3-3. CONTROL SYSTEMS FOR CONVEYORrZED DEGREASERS 

Control System A 

Control Equipment: None 

Operating Requirements : 

3 2 1. Exhaust ventilation should not exceed 20 m /min per m (65 cfm per ft2 ) 

of degreaser opening. unless necessary to meet OSHA requirements. Work place 

fans should not be used near the degreaser opening. 

2. Minimize carry-out emissions by: 

a. Racking parts for best drainage. 

b. Maintaining verticle conveyor speed at c 3.3 m/min (11 ft/min). 

3. Do not dispose of waste solvent or transfer it to another party such 

that greater than 20 percent of the waste (by weight) can evaporate 

into the atmosphere. Store waste solvent only In covered containers. 

4. Repair solvent leaks imnediately, or shutdown the degreaser. 

5. Water should not be visibly detectable in the solvent exiting the 

water separator. 

Control System B 

Control Equipment: 

1. Major control devices; the degreaser must be controlled by either: 

a. Refrigerated chiller, 

b. Carbon adsorption system, with ventilation > 15 m2/min per m2 (50 cfm/ft2) 

of air/vapor area (when down-time cove& are open), and exhausting <25 ppn of 

solvent by volume averaged over a complete adsorption cycle, or 

c. System demonstrated to have control efffciency ?quivalent to or better 

than either of the above. 

2. Either a drying tunnel, or another means such as rotating (tumbling) 

basket, sufficient to prevent cleaned parts from carrying out solvent liquid 

or vapor. 

3. Safety switches 

a. Condenser flow switch and thennostat - (shuts off sump heat if 

coolant is either not circulating or too warm). 

b. Spray safety switch - (shuts off spray pump or conveyor if the vapor 

level drops excessively, e.g. > 10 cm (4 in.)). 

c. Vapor level control thermostat - (shuts off sump heat when vapor 

level rises too high). 

4. Ilinimized openings: Entrances and exits should silhouette work 

loads so that the hveraye clearance (betweell parts and the edge of the 

degreaser opening) is either <lo cm (4 in.) or .10 percent of the width 

of the opening. 

5. Down-time covers: Covers should be provided for closing off the 

entrance and exit during shutdown hours. 

Operating Requirements . 

1. to 5. Same as for System A 

6. Down-time cover must be placed over entrances and exits of conveyorized 

degreasers imnedistely after the conveyor and exhaust are shutdown 

and removed just before they are started up. 
may decrease from 27 to ~20and .~ll (metric) tonsjyr for systems A and B, 

respectively. Thus, system B offers a much greater emission reduction per 

degreaser for conveyorized degreasers than for cold cleaners or open top vapor 

degreasers. 
3.3 REFERENCES 

1. American Society for Testing and Materials (ASTM) , Committee D-26, 

"Recommended Practice for New Source Performance Standards to Control 

Solvent Metal Cleaning Emissions." 

2. Surprenant, K. S. and Richards, D. Id. of Dow Chemical Company, "Study 

to Support New Source Performance Standards for Solvent Metal Cleaning 

Operations," Yo1 . 2, prepared for Emission Standards and Engineering 

Division (ESED), under Contract # 68-02-1329, Task Order #9, June 30, 1976. 

3. Ibid. 

4. Ibid, Appendix C-9. 

5. American Society for Testing Materials, Op. Cit. 

6. Surprenant, K. S., Op. Cit, Appendix C-12. 

7. Information provided by H. A. Rowan of Magnus Division of Economics Lab. 

Inc., S. Plainfield, N. J., by telephone to J. C. Bollinger, EPA 

March 28, 1977. 

8. Information provided by J. Picorney of Baron Blakeslee Inc., Chicago, 

by telephone to J. C. Boll inger , EPA, November 18, 1976. 

9. "Trip Report - Collins (now Rucker Ultrasonics) Inc., Concord, Calif ." 

EPA memorandum from J. C. Bollinger to D. R. Patrick, November 5, 1976. 

10. Surprenant, K. S., Op. Cit., Appendices C-3, C-5, and C-7. 

11. Ibid, pg. 4-5. 

12. JACA Corp., Fort Uashington, Pa., "Air Pollution Control of Hydrocarbon 

Emissions - Solvent Metal Cleaning Operations ,"prepared for EPA, Office 

of Technology Transfer, Seminar : "Upgrading Metal Machining, Fabricating, 

and Coating Operations to Reduce Pol 1ution ." 

13. Surprenant, K. S., Op. Cit., pg. 4-59. 

14. rbid, Appendices C-10 and C-11 . 
Ibid, Appendices C-4, C-5, and C-8. 

Ibid, Appendix C-7. 

Kearney, T. J., Detrex Chem. Inc., letter to J. F. Durham, EPA, 

February 17, 1976. 

Surprenant, K. S., Op. Ci t. 

Ibid. 

Ibid, pg. 4-16. 

Ihid, pg. 4-18. 

Informati on provided by F. X. Barr, Graymil 1s Co. , Chicago, by telephone 

to J. L. Shumaker, EPA, January 13, 1977. 

Information provided by K. S. Surprenant, Dou Chemical , Midland, Michigan 

by telephone to J . L. Shumaker, EPA, January 11 , 1977. 

Information provided by Hydroscience, Inc., Knoxville, Tennessee by 

telephone to J. L. Shumaker, EPA, March 24, 1977. 
4.0 COST ANALYSIS 


4.1 INTRODUCTION 

4.1 .1 Purpose 

The purpose of this chapter is to present estimated costs for applying 

alternative emission control techniques in the metal cleaning, or degreasing 

industry. Cost data will be provided for hydrocarbon controls on cold 

cleaners, open top vapor degreasers, and conveyorized vapor degreasers. 

These cost data will be presented for model new facilities as well as for 

model existing p1 ants. 

4.1.2 Scope 

With regard to cold cleaners, control cost estimates will reflect the 

use of the following techniques: 

1. drainage faci 1i ty ; 

2. mechanically assisted cover (spring 1 oaded) . 

The scope of this section includes both low volatility solvents, such as 

mineral spirits, and high volatility solvents such as 1,l ,I- trichloroethane. 

Costs will be presented for only one size cold cleaner facility. 

No incremental costs for housekeeping controls are presented in this 

chapter. A reasonable judgment is that such costs are negligible, particularly 

considering that they are offset by savings in recovering additional solvent 

from improved housekeeping. 

With regard to open top vapor degreasers, control cost estimates will be 

presented for two sizes of facilities that primarily use trichloroethylene 

sol vent or 1 ,l ,l -trichloroethane sol vents. The control cost estimates wi 11 

reflect the following techniques: 
1. use of a manual cover; 

2. use of a manual or powered cover in combination with extended freeboard; 

3. refrigerated chiller; 

4. carbon adsorber; 

As in the case of cold cleaners, incremental costs for housekeeping 

controls on open top vapor degreasers are not presented because they appear 

to be negligible. 

With regard to conveyorized vapor degreasers, control cost estimates 

will be presented for facilities that primarily use trichloroethylene or 

perchloroethylene solvents. The control cost estimates will reflect the use 

of the following techniques: 

a. carbon adsorber 

b. refrigerated chi1 1ers 

Again, incremental costs for housekeeping are not presented because they. 

appear to be negligible. 

4.1.3 Model Plants 

Control cost estimates are presented for typical model degreasers in the 

metal cleaning industry. Specific model plant parameters will be presented 

in the subsequent portions of this chapter. Admittedly, control costs may 

vary from one installation to another, perhaps even appreciably from the 

costs described for the models in this chapter. However, the difficulty of 

obtaining actual plant control costs requires use of model plants. To the 

extent possible, EPA has incorporated actual plant cost information into the 

cost analysis. 
Cost information is presented both for typical new model degreasers as 

well as for typical existing model facilities. Model degreasers depicting 

size, design, and solvent usage have been developed. The purpose of this 

is to show the relative variation in control equipment costs with these 

factors. Although the degreaser models chosen for the analysis are believed 

to be representative of degreasers used throughout the industry, no attempt 

has been made to span the range of existing degreaser designs and sizes. 

4.1.4 Capital Cost Estimates 

Control cost estimates comprise installed capital costs and annualized 

operating costs. The installed capital cost estimates reflect the cost of 

designing, purchasing, and install ing a particular control device. These 

estimates include costs for both major and auxil iary equipment, rearrangement 

or removal of any existing equipment, site preparation, equipment installation 

and design engineering. No attempt has been made to include costs for lost 

production during equipment instal 1 ation or start-up. For degreasing operations, 

most of the controls discussed will take a matter of hours for installation 

which should minimize delays in production. All capital costs reflect first 

quarter 1977 costs. In general, information for capital costs has been 

developed through contacts with degreaser equipment manufacturers. In addition, 

an EPA contractor study1 and EPA in-house files have been used to develop the 

capital costs. 

4.1.5 Annualized Costs 

Annualized cost estimates include costs for operating labor, maintenance 

and utilities, credits for solvent recovery, depreciation, interest, administrative overhead, property taxes, and insurance. Operating cost estimates 
have been developed on the basis of the EPA contractor study cited above. 

The number of annual operating hours was assumed to be 2250 hours. The cost 

of electricity is assessed at 4 cents per kilowatt-hour.' Solvent prices 

used were $0.20 per kilogram for mineral spirits, and $0.43 for trichloroethylene and $0.41 for the chlorinated blended solvent used in cold cleaning. 

These solvent prices are based on recent quotations from the Chemical 

Marketing ~e~orter. Maintenance costs for a1 1 control s (except housekeeping) 

were estimated to be 4 percent of the purchase cost of the equipment. Estimates 

of depreciation and interest costs have been developed by EPA based on the use 

of the capital recovery factor, an interest rate of 10 percent, and an equipment life of 10 years. In addition to costs for depreciation and interest, 

other capital charges include a 4 percent charge for administrative overhead, 

property taxes, and insurance. -

4.2 COLD CLEANERS 

4.2.1 Model Pl ant Parameters 

The model parameters that were used in developing control costs for cold 

cleaners are shown in Table 4-1. These parameters are based on industry 

contacts and EPA studies of the solvent degreasing industry. The most comnon 

type of cleaning is represented by low volatile solvent cleaning. Also shown 

is high volatile solvent cleaning, which is important from the standpoint of 

higher emission rates. The emission rates in Table 4-1 represent typical 

values. The recovered solvent values and the cost of solvent are used to 

estimate solvent credits which will reduce the annualized control costs. The 

assumed composition for the high volatility solvent blend is 60 percent 

1 ,I,1 -trichloroethane, 20 percent xyl ene, and 20 percent mineral spirits. 
I 

Table 4-1. COST PARAMETERS FOR MODEL COLD CLEANERS 

Working Area, rn2 

Solvent Used 

Uncontrolled Emission Rate, 

metric tons per year 

Emission Rate with Housekeeping Requirements , metric tons per year 

P 

cn' Solvent Recovered by Control 

System, metric tons per year 

Solvent cost, $ per kg 

Low Volatility High Volatility 

Sol vents Sol vents 

0.5 0.5 

Mineral Spirits Blended Sol vent 

0.25 0.40 

Source: EPA assumptions based on industry contacts, contractor studies and in-house files. 
4.2.2 Control Costs 

Costs for control of emissions from cold cleaners have been developed 

for the following cases for model new and existing cold cleaners: 

1. drainage facility for low volatility solvent cleaning 

2. drainage facility plus a mechanically assisted cover for high 

volatil ity solvent cleaning. 

The drainage facility consists of an external rack equipped with a drain 

line to return recovered solvent to the storage tank, which supplies the 

solvent for cleaning. The mechanically assisted cover consists of a spring 

loaded plunger which helps the operator to easily open and close the cover. 

The costs for these equipment features are presented in Table 4-2. 

Estimates are presented for installed capital costs, annualized costs, and 

the cost per kilogram of hydrocarbon control led. The capital costs for the 

drainage facility are the same for an existing cleaner as for a new one 

because of the ease with which it can be retrofitted. The capital costs 

for the cover are for the spring loaded plunger which can be retrofitted 

onto the cover of an existing cleaner. These costs were provided to EPA by 

a manufacturer of cold cleaning One hour of labor is assumed 

as the requirement for installing the spring loaded plunger. 

The cost of hydrocarbon control per kilogram of recovered solvent is 

quite sensitive to the value of the recovered solvent. Note that the low 

volatility solvent cleaner in Table 4-2 incurs a cost of $0.021 per kilogram :.I 

whereas the high volatility solvent cleaner saves $0.31 per kilogram for the 

new facility and $0.267 per kilogram for the existing facility. 

4.3 OPEN TOF VAPOR DEGREASERS 

4.3.1 -Model Plant Parameters 

The model parameters that were used in developing control costs for 

two sizes of open top vapor degreasers are displayed in Table 4-3. The 

two sizes represented are characterized by working area and solvent emissions. 

These parameters were selected as a rosult of industry contacts and EFA stL: 5; 

of the industry. The emission rates in Table 4-3 represent typical vafue-. 

The working are2 is used to determine costs for covers, refrigerdted ck,ii:ers, 

and frwboard extensions. The assumption used to estimate costs is t:ic\+ tr+ 

length of the workin9 area is twice the width. The recovered solvent vclucs 

and the cost of solvent are used ta estimate solvent credits \:F.ich a-e der!l~:-?a 

from the annualized costs of the control devices. 

4.3.2 Control Costs 

Costs for control of emissions from open top vapor degreasws nave been 

developed for the following cases for model new and existing degrsjsers: 

1. manual cover; 

2. manual 3r powered cover for working area exceeding 1.0 rr,' in 

combi nati 3n with extended freeboard; 

3. refrigerated chi1 1er; 

4. carbon adsarber. 

Table 4-4 presents the costs for these controls on the average sized 

degreaser, and Table 4-5 presents costs for the smaller degreaser. Costs 

are presented in terms of installed capital costs, annualized costs, and the 

cost per kilograr 3f hydrocarbon contrclled. 
Table 4-3. COST IIRIZAMFTERS rr)R t.1ODtL OPEN TOP VAPtlR @t.GkEASERS 

---_ _ -_ _ ___ _ _ - - _ --

Working Area, m2 

Uncontrolled Fmission Pate , 

metric tons per yezr 

Emission rate with housekeepin7 

requirements, metric ton:, per year 

Solvent recovered by -on tro l sys tern, 

metric tons per year 

a) Manual cover 

b) High freeboard and 

powered cover 

c) Chiller 

d) Carbon adsorber 

Sol vent Cost , $ per kg 

Manual cover and high freeboard. 

SOURCE : EPA assumpf-inns based on indu:;-". \ I rr~ntact,contrirctor studies, and in-house fi les. 


With regard to Tables 4-4 and 4-5, the installed capital for the carbon 

adsorber in the existing facility represents the worst retrofit situation 

to be encountered for this control device. This would occur if no steam 

capacity is available for solvent desorption, and space is limited. Retrofit 

capital would include a small steam boiler and an elevated platfom to provide 

space. For most retrofit situations, the installed capital would be somewhere 

between the costs for a new facility and the ?stirnates shown for the existing 

facilities. 

The retrofit factor for carbon adsorbers applied to existing degreasers 

was developed from an actual facil i ty.6 The cost of the carbon adsorber for 

the facility was $13,990; the boiler, $4,000; and the platform above ground 

level in the plant to house both the boiler and the adsorber, $3,300. 

The ratio of the boiler an3 platfom, costs to the carbon adsorber costs is 

approximately 0.50. 

The retrofit factor for the refrigerated chillers is also approximately 

50 percent, or in other words, retrofit costs are 50 percent more for existing 

degreasers than for new units. The basis for this is the study cited earlier 

(see reference 13. 

Retrofit costs for freeboard extensions, or high freeboards, and covers 

are difficult. to determine in some situat-ions. Based on contacts with two 

manufacturers of these devices, approximate instal 1 ation r~nl~ir~rneqts 

10 man-hours for manual cover^,^ 16 man-hours for freeboards, and 16 man-hours 

for powered covers. 

8 

The installed capital in Table 4-4 for the powered cover with extended 

freeboard in an existing facility includes $5,500 9 for digging a concrete 

pit. The purpose of the pit is to callow room for a hoist or a conveyor 
bringing parts to the cleaner. Such a problem most likely would not exist 

for small degreasers. Consequently, a provision for this type of retrofit 

penalty is provided in Table 4-4 but not in Table 4-5. 

Another difference to be noted in capital costs for the powered coverextended freeboard design is that the powered cover is required only for 

this degreaser with working area in excess of 1.0 rn 2 . Otherwise, the 

degreaser would be required to install only a manual cover. Note the 

difference in capital between the manual cover-extended freeboard design 

in Table 4-5 and the powered cover design in Table 4-4 for new facilities. 

In both Tables 4-4 and 4-5, the costs of hydrocarbon control per kilogram 

of recovered solvent are reported. These values will be used to develop the 

cost-effectiveness curves later in this chapter. As these tables indicate, 

the costs of hydrocarbon control vary considerably depending upon the size 

of the degrease;-, the type of control, and the amount of recovered solvent. 

As an illustration, carbon adsorber costs range from $0.091 per kilogram 

(Table 4-4) in a new facility for the typical degreaser to $0.583 per kilogram 

(Table 4-5) for the small degreaser. This is an indication that carbon adsorbers should be much less expensive for larger open top vapor degreasers. 

Conversely, the extended freeboard and manual cover combination is less expensive for the smaller degreasers than the similar combination with the powered 

cover on larger degreasers. This conclusion is shown by the difference in 

savings between $0.234 per kilogram for the typical degreaser in a new facility 

(Table 4-4) and $0.363 per kilogram for the small degreaser (Table 4-5). 
4.3.3 Cost-Effectiveness 

The purpose of this section is to provide a graphical analysis of the 

ccs t-effecti veness of a1 ternative control opt ions for various types of open 

top vapor degreasers. This analysis will attempt to relate the annualized 

cost per kilogram of hydrocarbon removal with degreaser size for each control 

option. 

Figure 4-1 is a presentation of the typical relationship for control of 

hydrocarbon emissions from open top vapor degreasers. Curves are shown for 

carbon adsorbers, refrigerated chillers, powered covers with extended freeboards, and manual covers. The size range shown in Figure 4-1 represents the 

approximate range of most degreasers (0.8 square meters to 18 square meters) 

based on EPA data, contractor studies, and contacts with degreaser manufacturers. 

The efficiencies of the control devices shown represent the capabil ity of the 

control device for reducing emissions from a well maintained degreaser (which 

has carried out a1 1 good housekeeping practices). A1 though detai 1 ed costs 

are presented for two model degreasers in Section 4.3, several more estimates 

were derived in order to define the curves with reasonable precision. 

The curves represent the retrofit costs for existing facilities. However, 

this constraint was somewhat relaxed for the powered cover option which does 

not include the cost of the concrete pit shown in Table 4-4. The reason for 

this is that the powered cover option with a lower control efficiency may 

be an acceptable option in those situations where the concrete pit is not 

necessary. On the other hand, ifthe pit were required, then the refrigerated 

chi 11 er with a higher control efficiency (45 percent) becomes more attractive. 

Far example, Table 4-4 shows for the degreaser with 1.57 square meters a 

cost of $0.928 per kilogram for the chiller and $0.115 f9r the powered cover 

with the concrete pit. 

An important concept for contr~l of 3egresser enissions is the fact 

that credits for recovered xlvsnt ~ffseto some extent the annualized 

costs of installing, operating, and maintaining a control device. In reviewing Figwe 4-1, the reader will observe the extmt to which solvent 

credits can more than affset the annuelizec! costs of the control device. 

This is graphically illustrated by the horizontal dashed 1ine of $0. per 

kilogram. This dashed line indicates that applicaticn of carbon adsorbers 

will result in an out-of-the-pocket expense to the o?eratw ~f the degreaser 

for a size below an approximate 6 square meters in working area. Similarly, 

refrigerated chillers will do the same for degreasers smaller than approximatc!! 

2 square meters. 

4.4 CONVEYORIZED DEGREASERS 

4.4.1 Model Plant Parameters -

The model plant parameta-s that were used in developing control costs fcf 

cmveyorized degreasers are displayed in Table 4-6 far monorail and cross-rod 

designs. These parameter selections are based on industry contacts and EPA 

studies cf the industry, in the same manner as cold cleaners and open tw 

vapor degreasers. The emission rates in Table 4-6 represent typical values. 

The working area is used to determine costs for refrigerated chillers. The 

assumption used to estimate chiller costs is that length of the working are;, 

or interface, is 2.7 times the width. The basis for this is an emission test 

study performed on a monorail degreaser.' The recovered solvent values and 

the cost of solvent are used to estimate solvent credits which will reduce the 

annualized control costs of the control devices. 
--- 

Table 4-6. COST PARAMETERS FOR MODEL CONVEYORIZED DEGREASERS 

Monorai 1 Cross-Rod - -

Working Area, m L 

Uncontrol led emission rate, 

metric tons per year 

Emi ssi on rate wi th housekeepi ng 

requirements, metric tons 

per year 

P 

I 

4 

Sol vent recovered by control 

system, metric tons per year 

Solvent cost, $ per kg 0.43 0.43 

Source: EPA assumptions based on industry contacts, contractor studies and in-house files. 
4.4.2 Control Ccsts 

Costs for control of emissions from cmveyorized degreasers have been 

developed for the fol 1owing control devices : 

1. carbon adsorbers 

2. refrigerated chillers. 

Table 4-7 presents the cc~sts for the mdel conveyorized degreasers. 

Costs are ?resented in terms of installed capital ccsts, annualized costs, 

2nd the c~st per kilogram of hydrocarbon controlled. The installed capital 

for the carbon adsorber in the existing facility represents the worst retrofit 

situatim to be encountered. This would occur if no stea~capacity is available 

for regeneration of adsorbed solvent and space is limited. Retrofit capitzl 

ir.ciudes a small steam boiler and an elevated platform for the carbon adsorber. 

The rztrofit factor applied to the new source costs fw the carbon adsorber 

is the same as the retrofit factor used for open tcp vapor degreasers. 

Most existing facilities already have steam raising capacity to operate 

a stiY to reclaim dirty solvent. These facilities could possibly schedule 

their stean boiler to desorb the carbon bed during periads when the still is 

not used. For most retrofit situations, the installed capital would lie 

somewhere between the costs shown for new and existing facilities. 

The figure of $8,550 shown for the existing facility on the monorail 

degreaser compares reasonably well with a figure of $8,294 (1975 dollars) on 

an actual facility.'' The latter would be $9,123 in 1977 dollars based on the 

use cf the Chemical Engineering Plant Index. The retrofit factor used to 

estimate costs for chillers is the same as the one used for the chillers on 

open top vapor degrsasers. 

The cost of hydrocarbon control pzr kilogram shol~n in Table 3-7 for 

the carbon adsorber on a new faciljty costs $0.10 ?er kilogram for the crossrod degreaser. On the other hand, the application of a carbon adsorber results 

in a saving of $0.201 for the monorail degreaser. On the retrofitted facil i ty, 

the application of the carbon adsorber costs $0.289 per kilogram for thc crcisrod degreaser but results in a savings of $0.125 for the monorail degreaser. 

It must be noted that the difference in cost for the two degreaser models 

is sensitive to the emission rate and potential solvent recovered because the 

annualized costs of instailing an3 operating a carbon adsorber are assumed +o 

remain approximately the same in both cases. This is an important consideration 

in the i~pact of control upon the owner of the degreasers. 

The refrigerated chi1 ler appears to be inexpensive to the user regardless 

of the type of degreaser and the degree of retrofit. This is demonstrated by 

the savings shown for all cases in Table 4-7. 

4.4.3 Cost-Effectiveness 

This section provides a graphical analysis of the cost-effectiveness 

for alternative control options on conveyorized degreasers. This analysis will 

relate the annualized cost per kilogras of hydrocarbon control to degreaser 

size for each control option. 

figure 4-2 shows a relationship of cost versus size for carbon adsorbers 

and refrigerated chillers on monorail degreasers. The assumptions regarding 

the size range and control efficiencies are similar to those outlined for open 

top degreasers. The size range of most monorail degreasers is 1.9 to 18 

square meters. As shwn in Figure 4-2, the application of carbon adsorption 

results in an out-of-the-pocket expense for degreasers smaller than approximate1 

2 square meters in working area. 3y the same token, carbon adsorbers can 

be quite cost-effective for degreasers with large air to vapor working areas. 

Figure 4-3 shows a siniilar relationship for cross-rod degreasers. There 

are two important differences between Figure 4-3 and Figure 4-2 for the 

monorail degreasers. First, the size range is narrower for the cross-rod 

degreasers. The range for most xoss-rod degreasers is 1.9 square meters to 

4.8 square meters. For monorail degreasers the range is 1.9 to 18 square 

meters. Second, controls are generally more expensive for cross-rod degreasers 

than for monorail degreasers. In particular,the cost of carbon adsorption 

appears to be mcre than offsetting solvent credits along the entire size range. 

This is shown by the position of the carbon adsorption curve in relation to 

the horizontal 1 ine of $0. per kilogram control in Figure 4-3. The information 

depicted in the two figures for monorail and cross-rod degreasers demonstrates 

the variation in costs with degreaser design that can be anticipated for 

conveyorized degreasers. 

3.6 REFERENCES 


Surprenant, K. S. , and Richards, D.W. , "Study to Support New Source 

Performance Standards for Sol vent Metal Cl eani ng Operations " prepared 

for the Environmental Protection Agency, Contract No. 68-02-1329, 


Dow Chemical Company, Midland, Michigan, June 30, 1976. 


Anon., "Typical Electric Bills 1976," Federal Power Commission. 


Chemical Marketing Reporter, Schnell Pub1 ishing Co., March 7, 1977. 

Private communication, Frank L. Bunyard, OAQPS, Environment21 Pr~tectior 

Agency, to Jerry Shields, Vanager of Marketing, Graymills, Chicago, 

August, 1976. 


Private communication, Frank L. Bunyard, OAQPS, Environmental Protection 

Agency, to Jerry Shields, Manager of Marketing, Graymills, Chicago, 


August, 1976. 


Surprenant and Richards, x.-cit., Appendix C-4. 


Private communication, Frank L. Bunyard, OAQPS, Environmental Protection 


Agency to Parker Johnson, Vice President of Sales, Baron Blakeslee Corp., 


Cicero, Illinois, March 16, 1977. 


Private communication, Frank L. Bunyard, OAQPS, Environmental Protection 

Agency to Dick Clement, Detrex Chemical, Detroit, Michigan, March 21, 1977.. 


Surprenant and Richards, OJ. -

cit., page 4-97. 

Surprenant and Richards, 9.-cit., Appendix C-7. 


'

Ibid page 10. 
CHArTEF! 5. FDVERSE ENVIRONMENTAL EFFECTS 

0' AFPLYING THE TECHNOLOGY 

5.' AIR IMPACTS 

No significant adverse air impacts should result from solvent degreas 4r1g 

regulations, a1 though gross ,:eel icence wjth maintenance and operatic- 2r' 

control devices could increase emissions in individual cases. Examryes are 

carbon adsorotion systems operating with spent or saturated adscrbent, 

maladjusted refriger?.tion sycterns and excessive vent; lation rates. 'r3per 

maintenance and o?eration of these controls will eliminate increases and 

effect significa~t reduciicns in enissions. 

Improper incineration cf waste solvent is another possf ble area ,"here 

emissions could increase. If chlorinated waste solvents are incinerated 

without subsequent gas cleaning, hydrcchlor'c acid, chlorine, phosgene and 

cther potenti a1 ly harmful Iy emissions could result. Scpkisticated ga, cleaning 

equipment iz req~iired t~ ccctrol these e~i ssions. 

Eciler eaissqons r,lay increase due to the stearr required tc? distiyl waste 

solsrent and recjenerate carbon ~eds, b lt iri general these increa~es tviii be 

insigificant compared tc the emission reductions obtained cy this eqiri o ieqt. 

5.2 MTER IlzlPACTS 

5.2. I Waste Solvent Disposal 

The major potential water pollutants from solvent degreasers are waste 
solvents. Waste solvent can enter natural water systems through sewer 

disposal or as leachate from landfi 11s. Additional air pollution controls 

are not expected to allow sewer or improper landfill disposal because much 

of the solvent would eventually evaporate. Thus, water pollution would 

probably be diminished by additional air pol 1 ution control. 

5.2.2 Steam Condensate from Carbon Adsorption 

The largest impact on water quality resulting from the control of solvent 

r~reta; cleaning comes from the use of carbon adsorption. Steam used to desorb 

the solvent is condensed with the solvent and separated by gravity. Water 

* 

soluble stabilizers and some solvent will remain with the water and eventuall: 

enter the sewer system. 

Stabilizers are organic chemicals added in very small quantities to 

chlorinated solvents to protect them from decomposition. Stabilizers 

evaporate from the degreaser as does the chlorinated solvent and both are 

amenable to collection by adsorption. Furthermore, many stabil izers are 

water miscible and thus will be removed almost completely from the process 

during steam desorption. Chlorinated solvents are only slightly water 

miscible but small quantities wi 11 remain with the water. 

5.2.2.1 Chl ori nated Sol vent i n Steam Condensate -

Solvent discharge into the sewer can typically reach 190 kg (0.13 rn 3 

or 

35 gallons) per year. This assumes solvent at a concentration of 900 ppm in 

the condensate and a total of about 40,000 gallons per year of steam condensat 

* 

Stabilizers may also be referred to as inhibitors or additives. Some - stabilizers are normally lost into the water of the degreaser's water 

separator, but the quantity of this water is negligible compared to that 

from steam stri pped adsorption systems. 
In comparison, the reduction in atmospheric emissions from the degreaser by 

3 using the carbon adsorber wou Id typically be 14,000 kcj (10 n or 2500 gallons) 

per year. Therefore, in this case potential sewer emissions of solvent 

(before evaporating) are less than about 1.5 percent of the degreaser emissions 

prevented by the carbon adsorber. The above estimates are based on two tests 

which measured the solvent content in waste water from adsorbers used on 

chlorinated sol vents. 132 

5.2.2.2. Stabilizers in Steam Condensate -

In addition to chl ori nated compounds, steam condensate wi 11 contain small 

amounts of solvent stabilizers. Nhen the condensate is disposed of most of 

these stabilizers, because of their volatile nature, will eventually evaporate 

The highest sewer stabilizer emission would probably occur with 1,1,1- 

tri chl oroethane which requi res considerable amounts of water soluble stabilizers. 

Assuming a solvent recovery rate of 10 m' per year (2500 gallons per year), 

5 percent stabilizers in the 1 ,l ,l-trichloroethane blend and 40 percent of the 

stabilizer being water soluble, the stabilizer effluent to the sewer would be 

3 0.2 m per year (50 gallons per year). This would be the worst case; however, 

and it may not be representative of any actual degreasing processes. The 

captured solvent vapor does not necessarily contain as high a precentage of 

stabilizers as does the original liquid solvent. For this reason even systems 

using 1 ,l ,l -tri chl oroethane may not emit this amount. Furthermore, other major 

solvents contain less water sol uble stabi 1izers than 1 ,l ,1-trichloroethane; 

therefore, the average stabilizer emission would be less than 0.2 m 

3 

per year. 

A method for assessing the impact of the stabilizers would be to analyze 

the toxicity, water sol ubi 1i ty, percent composition, volatility , and BOD 

(relates to the decomposition rate) for each stabi lizer. Unfortunately, 

percent compositions are generally considered trade secrets by sol vent 
manufacturers. However. a litersture search yielded some data which is given 

iri Appe,:dix B 6 ? 

After studyina the effects of some of the more toxic substances, it was 

concluded that only di isobutylene and triethylamine. which are used in 

trichloroethylene, present any significant potential problem with regard to 

i'sh toxicity.' Two other stabi 1 izers of possible concern are acryloni trile 

and epichlorohydrin, although the data on them are not vet conclusive. 

If the quantity of stabilizers and solvent dissolved in the steam 

condensate were found to be significant, then air sparging could dramatically 

reduce the levels of a1 1 these compounds. During sparging it may be advantageous to vent the off-qas back into the adsorber. Thus, atmospheric emission 

of the sparge off-gas would be controlled. Furthermore, more stabilizer would 

tend to remain in the recovered solvent. Although sparging appears to be an 

inexpensive means of treating the waste water, the data thus far have not 

indicated a significant environmental need. 

5.2.3 Effluents from Water Separators 

Water separators on vapor degreasers and distillation units collect a 

small amount of contaminated water. This is generally less than a gallon or 

two per day per degreaser, and should not create a significant impact on water 

qua1ity. De-icing of refrigerated control systems which operate below 32O~, 

will increase this, but probably not enough to create a problem. Steam 

stripping of still bottoms in distillation units to reduce solvent content will 

also increase this amount, but again probably not enough to create a problem. 

5.3 SOLID WASTE IMPACT 

There appears to be no significant solid waste impact resulting from 

control of solvent degreasers. The quantity of waste solvent would not increase 

as a result of controls but should decrease because of increased practice of 
distillation and incineration. 

Carbon used in carbon adsorber beds is discarded periodically. Vendors 

and users have estimated the life of carbon at up to 30 years but replacement 

is generally recommended every 10 to 15 years. Assuming there are up to 

7,000 degreasers, using 50 kg of carbon each and averaging a 10 percent annual 

replacement rate, disposal of carbon from adsorbers could reach 35,000 kg 

annually for the nation. This amount would never be realized, however, because 

spent carbon can easily be reactivated. Most major activated carbon manufacturer: 

are equipped for this task. 

5.4 ENERGY IMPACT 

Carbon adsorbers, refrigerated chillers and distillation units are the 

principal energy consuming control devices used for controlling degreasing 

emissions. 

A carbon adsorber consumes the areatest amount of enerav because of st.~arn 

required for desorption; however, this energy expenditure is far less than the 

energy required to manufacture replacement solvent. A typical carbon adsorption 

system on a degreaser may consume 35 kw (120,000 Btu per hour) of energy and 

recover 7 kg per hour (15 pounds per hour) of solvent. This energy consumption 

estimate is based on the following assumptions: 4 kw per kg solvent for steam 

production, 3 to 12 kw (10,000 to 40,000 Btu per hour) for fan power. A carbon 

adsorber may typically increase the energy consumption of a vapor degreasing 

4
 system by 20 percent. 

A typical refrigerated freeboard chi 1ler may increase a degreaser ' s energy 

consumption by 5 percent. The chi1 ler would consume 0.7 to 2.2 kw (2500 to 7500 

Btu per hour) if it ran at 100 percent output. The above values are derived 

from assuming an average of 1 to 3 horsepower for compressor ratings. A chiller 
may reduce emissions by about 1.5 kg per hour (3 1bs per hour) on a typical 

2

open top vapor degreaser having a 1.7 m (18 square feet) opening. Thus, 

roughly 0.5 kw . hr may be spent to save 1.5 kg of solvent. 5 

Solvent distillation requires about 0.1 to 0.2 kw hr/kg of recovered 

solvent (150 to 300 Btu/pound). Assuming a steam cost of 0.78 centsjkw-hr 

(2.30 $/lo6 Btu), then the energy costs 0.08 to 0.15 $/kg of distilled solvent 

(0.035 to 0.07 t/lb). Considering that chlorinated solvent costs about 45 

$/kg (20 $/lb), the cost of the distillation energy appears to be an insignificant 

expenditure. 6 

Other vapor control devices are the powered cover and powered hoist. 

Their energy consumption is insi gifi cant because the electric motors are small 

and are used only for short durations. 

The energy value of the solvent saved is much greater than the energy 

expended to conserve the solvent. The energy value of the solvent is composed 

of the sol vent manufacturing process energy plus the heat of combustion lost 

when the processed petroleum feedstock is not used as fuel, plus other energy 

consumed to replace the lost solvent. The heat value of the feedstock alone 

is greater than the energy required to recover the solvent. Without doubt 

control of solvent emissions, by any method, would have a favorable impact on 

energy consumpti on. 

5.5 OTHER ENVIRONMENTAL CONCERNS 

The only other consideration might be blower noise associated with carbon 

adsorbers. This noise does not affect the environment external to the plant, 

although it would be noticeable inside the plant near the adsorber. Noise levels 

have not been measured because they have not appeared significant when compared 

to the normal noise level in machine shops and other manufacturing areas where 
carbon adsorbers are found. While noise does not seem to present a 


significant environmental problem, it is worthy of consideration when 


choosing the in-plant location for a carbon adsorber. This problem could 


be resolved by utilizing existing noise suppression technology. 

REFERENCES 

1. Sc,iei1 , George 'X. , Mi o:,est Research Institute. "Source Test 

Tri chl oroethyl ene Degreaser Adsorber ." EPA Project Report No. 

76-DEG-1. 

2. Schei 1, George !,I. "Test of Industrial Dry Cleaning Operation," 

EPA Report No. 76-DRY-2. 

3. Surprenant, K..S. and Richards, D.!d., Dow Chemical. "Study to 

Support New Source Perfornlance Standards for Solvent Metal 

Cleaning Operations," Prepared for EPA, Contract No. 68-02-1329, 

Task Order No. 9. 

4. IBID. pg. 7-8. 

5. IBID. pg. 7-9. 

6. IBID. pg. 7-9. 
CHAPTER 6. COMPLIANCE TEST METHODS 

AND MONITORING TECHNIQUES 

It is not expected that emission testing will play a significant part 

in a compliance program for degreasers. This results from the difficulty 

in measuring emissions and in enforcing emission standards, as discussed in 

Chapter 7. Instead, equipment and operating practice standards appear to be 

more realistic options. In these, compliance relies principally upon 

observation to determine if control equipment is designed and functioning 

properly and to ensure that operating practices, as observed under normal 

conditions, are being properly fol lowed. 

Although the compliance emphasis should be on equipment and operating 

practice standards, the emission rate of a degreaser system may be useful 

supplementary information. For example, if emissions are greater than 

average for a system of a certain size, it is an indication that the system 

is inadequately or improperly controlled. Emission rates can be estimated 

roughly with an analysis of solvent purchase and inventory records and more 

accurately with a material balance test. 

Other emission tests that could be useful in compliance programs are 

tests for leaks and tests of carbon adsorption off gas streams. The costs 

of these tests will often be offset by solvent savings from reduced emissions. 

An investigator with some familiarity with degreasers and carbon adsorption 

systems can frequently identify defective systems with a brief inspection and, 
thus, avoid the expense of emission testing. 

6.1 OBSERVATION OF CONTROL EQUIPMENT AND OPERATING PRACTICES 

Ifthe degreasing regulation specifies equipment and operating 

standards, the compliance test is basically one of visual observation. The 

observation control equipment and operating practices mainly involves checking 

throuqh a list of requirements; however, a basic understanding of degreasing 

systems is necessar.~. The details to observe are described in Sections 3.1 

and 3.2 of this report. 

6.2 MATERIAL BALANCE 

A material balance test seeks to quantify the amount of solvent input 

into a degreaser over a sufficiently long time period so that an average 

emission rate can be calculated. The major advantages of the material 

balance method are: (1) the total system is checked, (2) the test is simple 

and does not require expensive, compl icated test equipment, and (3) records 

are usually kept of solvent use, and generally all solvent added is make-up 

for sol vent emitted. 

The disadvantage of the material balance method is that it is time 

consuming. Because many degreasers are operated intermittently and because 

there is inaccuracy in determining liquid levels, an extended test time is 

needed to ensure that calculated emission rates are true averages. 

In order to perform a material balance test, the following general 

procedure should be followed: 

1. Fi 11 the solvent sump (or bath) to a marked level. 

2. Begin normal operation of the degreaser, recording the quantity of 

make-up solvent and hours of operation. 
3. Conduct the test for about four weeks, or until the solvent loss is 

great enough to minimize the error in measurement. 

4. Refill the solvent sump to the original, marked level, recording 

the volume of solvent added. The total volume of solvent added during the 

test period approximately equals the solvent emitted. 

Although a highly accurate material balance is not usually necessary, 

the following modifications will improve the accuracy of the test. 

1 . Clean the degreaser sump before testing . 

2. Record the amount of solvent added to the tank with a flow meter. 

3. Record the weight and type of work load degreased each day. 

4. At the end of the test run, pump out the used solvent and measure 

the amount with a flow meter. Also, approximate the volume of metal chips 

and other material remaining in the emptied sump, if significant. 

5. Bottle a sample of the used solvent and analyze it to find the 

percent that is oil and other contaminants. The oil and solvent proportions 

can be estimated by weighing samples of used solvent before and after boil ing 

off the solvent. Calculate the volume of oils in the used solvent. The volume 

of solvent displaced by this oil along with the volume of make-up solvent 

added during operations is equal to the solvent emission. 

Proper maintenance and adjustment should be performed on the degreaser 

and control system before the test period. 

6.3 OTHER EMISSION TESTS 

An emission measurement test on the off-gas stream from a carbon adsorber 

may occasionally be necessary. However, this has value only in evaluating the 

adsorption efficiency not the control efficiency of the system. This test 

will give no indication of the effectiveness of the adsorber's collection 
system; neither will it guantify emissions from waste solvent evaporation, 

leakage losses, carry-out or sump evaporation. 

The better sampling systems for organic solvents use gas chromatography 

(GC). Techniques for using GC are discussed in EPA-450/2-76-028, "Control 

of Volatile Organic Emissions from Stationary Sources. Volume 1: Control 

Methods for Surface Coating Operations." A specific method for perchloroethylene is also detailed as EPA Method 23: "Determination of Total Non-Methane 

Hydrocarbons as Perch1 oroethyl ene from Stationary Sources. " Fi nal ly , a method 

for another chlorinated hydrocarbon is EPA Method 106: "Determination of Vinyl 

Chloride from Stationary Sources." For stack measurments, velocity and flow 

rate can be determined using EPA Methods 1 and 2. 

One EPA emission test measured carbon adsorber inlet and outlet concentrations both with a flame ionization detector and with a gas chromatograph, 

using integrated gas-bag samples. The methodology and test results are detai 1 ed 

in EPA Project Report No. 76-DEG-1. 

Useful tools in locating leaks and other points of emission are the ha1 ide 

torch and the Drager tube. The halide torch is useful as a locating device 

that will detect sources of halogenated hydrocarbon vapors. The Drager tube 

will quantify the vapor concentration in ppm and is useful in survey work. 

These should be useful and relatively inexpensive means to locate sources and 

quantify by magnitude the hydrocarbon loss. They would allow a maintenance 

check of control equipment operation and prevent inadvertent losses. 
CHAPTER 7. ENFORCEMENT ASPECTS 

Emission standards are general ly not practi cal to enforce for sol vent 

degreasing for three reasons: (1) there is an extremely large number of 

solvent degreasers, (2) emission tests are time consuming, and (3) there 

are complexities in speci fying acceptable emission rates. In order to 

avoid use of emission standards and to provide quick, inexpensive compl iance 

testing, equipment and operational standards are recommended. 

Even though visual inspection is relatively quick and inexpensive, it 

can not easily determine whether or not the equipment and operation is in 

compliance. For example, on cold cleaners it must be determined whether 

or not it is practical to install an internal drainage facility. Also, for 

highly volatile solvents in cold cleaners, one must decide whether or not 

the cover can be classified as easily operable. Another example i s i n 

deciding what is significant liquid carry-out. Even though Chapters 3 and 6 

give background on making deci sions for visual inspection, the inspector 

still needs an adequate background knowledge of degreasing operations to deal 

with some of the less definite aspects of enforcement. 

Because most emission controls serve to reduce the emissions inside the 

plant, it is reasonable to consider combining enforcement by OSHA and EPA for 

control of sol vent degreasers. The possi bi 1 ities of a cooperative enforcement 

program with OSHA and EPA are being explored. 
7.1 REGULATORY APPROACHES 

There are four types of regulations which can be considered for solvent 

r8ietal cleaning: (1 ) emission standards, (2) equipment specification 

standards, (3) operational requi rement standards, and (4) solvent exemption 

standards. Equipment and operational standards appear to be superior to 

either emission standards or solvent exemption standards. Each of these 

approaches is discussed in the following sections. 

7.1.1 Emission Standards 

Emission standards requi re an emission measurement. A material balance 

is the most accurate measurement method for compliance testing but could 

require over a month for one test. If solvent consumption records kept by 

the degreasing operator are accurate and complete, they could satisfy the 

requirement for a material balance test. 

If enforcement were only to determine whether or not degreasing systems 

are designed properly, then one emission test would be sufficient for each 

degreaser model. However, adjestment, maintenance, and operation of degreasers 

varies so greatly that the actual level of emission control cannot be expected 

to be sinii 1 ar, even for identical degreaser models. Thus, individual degreasers 

rather than models must be evaluated. 

An emission standard may be a simple emission rate or it may be related 

to another variabie, such as work load tonnage, heat input, idling mode 

emission or uncontrolled emission rate. The three most reasonable alternatives 

for emission standards are: (1) simple emission rate, (2) emission rate per 

open area of degreaser and (3) emission rate per work load tonnage. These 

alternatives are briefly discussed below. 

The simple emission rate standard provides a conventional regulation 
that is readily understood. However, different values of acceptable emission 

rates would have to be provided for each type of degreaser. It would also 

not be reasonable to require the same emission rate for large degreasers as 

for small degreasers; this would require an emission rate based on the open 

area of the degreaser. 

A1 though eniission rate is related to the area of the air/vapor interface, 

an important consideration is the amount of work load processed. Thus, possible 

improvement to an eniission standard would be to relate it to the work tonnage, 

for example, a specified amount of solvent emission could be allowed per ton 

of work load cleaned. This type of standard would be particularly useful if 

the work loads were consistent in their surface-to-wei ght ratio and their 

tendency to entrain solvent; however, this is rarely the case. For example, 

degreasing a ton of hollow rivets would result in much greater solvent 

emissions than would degreasing a ton of cannon balls. 

Generally, for an emission standard to apply fairly to all degreasing 

applications, it must relate to the amount and type of work load. Preferably, 

the emission standard should also consider the type of degreaser and its size. 

Even if an emission standard could be dev ised to satisfy these requ iremen ts , 

it would be d i f f i c u l t t o enforce and very burdensome for degreasing opera tors 

to have to record quantities and types of pi r t s c l eaned . 

7.1.2 Equi pment Standards 

Equipment standards can be easily enforced and fairly applied to the larse 

variety of degreasing applications. Equipment standards would not require 

the same performance by a degreasing operation with a large work load as that 

with a small work load. 

The equipment requirement must be specific enough to ensure effecti ve 

control but not so restrictive that it would discourage new control technology. 
For example, the high freeboard, refrigerated chi 1ler, and carbon adsorption 

venti 1ati on rate can be specified to ensure sufficient emission control. 

The specifications usually represent an engineering judgement by experts in 

the degreasing fields and could be revised as new test data are collected. 

Another type of specification for control gquipment is the exemption of 

degreasers that are too small for control equipment to be economically 

reasonable. Parti cularly in the case of refrigerated chi 1lers and carbon 

adsorbers , i ns tall ati on coul d be too expensi ve for snal 1 degreasers and coul d 

even cost more than the degreaser itself, thus, a lower level cut-off of 

approximately 1 m 

2 for open top vapor degreasers is recommended. Because 

of the continuing developments in emission control for solvent degreasing, 

provision must be made to approve control systems that do not satisfy the 

requirements specified in this document but may still be effective. Section 

3.2 describes equipaent and operational standards that can be formulated. 

Operational Standards 

As with equipment standards, operational standards can apply to almost 

all degreasing applications, regardless of their size and type of work load. 

Operators will play a key role in achieving emission control ; however, they 

will have little incentive to follow complex standards. Thus, the standard 

must be simple, understandable, and precise. The numerous operational 

requirements can be more easi ly remembered by the operator if a permanent, 

conspicuous label is attached to the degreaser summarizing them. The 

difficulty of enforcement may be minimized by educating the supervision and the 

operator to the fact that proper operation and control equipment maintenance 

will usually provide a net profit from solvent savings. 
7.1.4 Solvent Exemption Standards 

There is very little flexibility in converting from non-exempt to 

exempt solvents. A recent EPA notice (42 FF. 35314) has suggested that the 

only materials that should be a1 lowed exemptions are methane, ethane, 1 ,I,Itri chloroethane, and trichlorotri fl uoroethane. This choice is further 

1imi ted because of differences in sol vency , fl ammabi 1 ity , cost, chemical 

stabi 1 ity and boi 1ing temperature. In general , the exempt sol vent approach 

to reg.ulating solvent metal cleaning is not recommended, because it does 

not achieve posi tive emission reduction. The rationale for this 

is discussed further in Chapter 1. 

7.2 AFFECTED FACILITIES - PRIORITIES 

Since there is a wide diversity of solvent degreasers, the definition 

of faci 1 ities affected by degreasing regulations must be accurate. A1 though 

a1 1 solvent degreasers may be subject to potential regulations, there are 

an extremely large number of degreasers; thus, those with greater emissions 

should be given higher priority for enforcement. 

7.2.1 Definitions of Affected Facilities 

The following defines the three types of solvent degreasers that can 

be regul ated. 

1. Cold cleaner: batch loaded, non-boiling solvent degreaser 

2. Open top vapor degreaser: batch loaded, boiling solvent degreaser 

3. Conveyorized degreaser: continuously 1oaded, conveyori zed sol vent 

degreaser, either boiling or non-boiling. 

7.2.2 Priorities of Enforcement 

Individual degreasers that yield the greatest emission reduction at 

reasonable cost should have the highest p r i o r i t y f o r enforcement. Within 
that grouping, priority operations are vapor degreasi ng and waste sol vent 

disposal from all degreasing operations. The lowest priority is assigned to 

cold cleaners , especi a1 ly niai ntenance type wi th 1ow vol ati 1i ty sol vents, such 

as those used with automotive repair. 

An emission reduction of 5 to 15 tons per year can be achieved by 

control 1ing a typical open top vapor degreaser or conveyorized degreaser. 

In comparison, emissions from individual cold cleaners usual ly cannot be 

reduced by more than 0.1 tons per year (see Appendix B). Even though 

conveyorized degreaser emissions can be reduced more than open top vapor 

degreasi ng emissions on the average, regulation of conveyori zed degreasers 

before open top vapor degreasers is not recommended, because-conveyorized 

degreasers emit significantly 1ess sol vent than do open top vapor degreasers 

for an equivalent work load. Thus, it would not be advantageous to encourage 

degreaser operators to choose open top vapor degreasers in order to avoid 

regulations on conveyori zed degreasers. 

Waste solvent is a high priority area for control. Controls could be 

directed towards sol vent users, sol vent producers, and/or sol vent 

disposal facilities. It is the reeponsibility of the solvent user to properly 

dispose of his waste. Facilities which accept waste solvent must use 

disposal methods which minimize evaporation. It is recommended that solvent 

producers 1abel new solvents to indicate regulations on waste disposal. For 

example, a label could read that waste solvent should not be disposed of so 

that it can evaporate into the air or pollute the waters. In addition to 

regulating degreasing waste solvent disposal a more comprehensive enforcement 

program which would cover disposal of all waste solvent and similar volatile 

organic materi a1 s shoul d be considered,. 
Although enforcement of regulations on cold cleaners is made difficult 

by their large numbers, it can be practical when enforcement trips are combined with other purposes, or if there are numerous cold cleaners and 

other solvent degreasers at a particular plant. 
APPENDIX A. TEST RESULTS 

APPENDrX A: TEST RESULTS 

CONTENTS 

Page 

A. 1 Test results from Dow Report . . . . . . . . . . . . . . . . . . . A-1 

A.2 EPAColdCleanerTest Report. . . . . . . . . . . . . . . . . . . A-3 
A.l TEST RESULTS FROR TtlE DON REPORT 

Under contract to the EPA the Dow Chemical Company tested eleven solvent 

metal cleaners. Detailed reports of each test are contained in the Appendices 

to the document: "Study to Support New Source Performance Standards for Solvent 

Metal Cleaning Operations," prepared under EPA contract no. 68-02-1329 by 

K. S. Surprenant and D. W. Richards and dated April 30, 1976. A summary of 

the results is given in Table A-1 . 
- 

TABLE A-!. TEST RESULTS FROW OOH REPORT 

SATISFACTORY CONTROL SY STEM5 

Lbw Report' Uncontrolled Emission Rate Contrllled Ernis~ion Controlled 

Appendixl User oegreaser* vapor Area Solvent (gal/unit) (lb/ft2-hr) (galjunit) (lb/ftz.hr) Efficiency Control System Cments 

C-5 Pratt Yhitney OTW 65" 110" l.!,l 97.5 galjwk 0.16 58.4 galiwk 0.10 40; Cover-pneumatically Uncovered to1 24 1' and 

49.6 ft2 ijowerid 7 da,,/wi 

C-2 Eaton OTVD Tri. lblton 99 Iblton 239 Cover jmanua:) iio much infarnation on the test. .>,

I , III ibiton 80 lbiton 289 

C-12 Dm Lab OW0 24.2"x22" 1.1.1 0.373 0.373 0 TR = 0.5 Idle (no work lc?dc,), moderate draft 

3.7 ft2 0.373 0.273 27% = 0.75 

0.373 0.167 552 = 1.0 

24.2"x22" 1.I.1 0.955 FR = 0.5 idle, quipt ?lr 

3.7 ft2 0.955 0.051 46a 0.75 

0.955 0.054 43% 1 .O 

C-3 Hamilton OTYO 15 ft2 llethylene i.5 gal opday 0.186 4.53 gallopday 0.112 >40% Cold Trap Work load when CT on was 50% more than when 

Standard (1203) Chloride 6.43 gal/day 3.67 gal /day ,43% FR = 0.83 (covered CT off +fb 40Z. 

during disuse) 

OTVD 11.1 ft2 kethylene 3.63 gallopday 0.450 2.60 gal/opday 0.322 28% Cold Trap Inaccurate results. The ObR deg is expected to 

(OhR) Chloride 2.9 qallday 1.73 gallday 40% FR = 0.75 have a higher n, due to being uncovered. OLR had 

(never covered) 1 % wo loa s per operating day whereas X203 had $1!o i3 WCtdiopiay. 

P C-10 ' Vic OW0 12'x4.5' Tri. 108 gal/wk 0.605 38 galiwk 0.213 65% Carbon adsorpt:on Yentilation rate of 10: i:m;ft?. Accuracy of record-keepinq N 54 ft2 is reported by Ocw to be poor. Thus. accuracy of results 

would be poor. 

C-7 Schlage Lock CVD- 41.3 ft2 Perc. 19.5 gal/wday 0.79 7.5 gallwday 0.304 62% Chiller Range of n 1s 45 to 65*. knorai l 

C-11 Y. Electric CNO Tri. 0.063 gal/ft2 of - 0.025 gal/ft2 - 60% Carbon adsorption 

Hawthorne def luxer cl rcui t board 

23.8 gallwday 10.4 gal/wday 

UNSATISFACTORYCOITROL SYSTEKS 

C-5 Pratt Uhitney OTVD 5Vx90" 1.1.1 58 gal/wk 0.138 49 galiwk 0.117 16% Cold Trap FR = 59%. Cold Trap desion tested here was reported as an 

35 ft2 obsolete model. t overed during disuse. 

C-8 Super Radiator OTVO 6'xlZ' Perc. 49 gal/day 1.53 37 gal/day 1.14 -8% Carbon Adsorption Defective adsorption system - bre kthrough; insufficient 1 72 ft2 FR 0.04 ZFR- 0.1. Only 37 cfmlft 

C-4 Hewlette MD 214 Carbon Adsorption LOW contml efflc lency of the adsorption system is thought 

Packard Monorail to be because of poor ventilation design. 

Developer 

C-9 J. L. CVO Tri 1.4 gallhr 1.06 gal/hr 25% Carbon Ad~orption Materia: Falance results 

Thonpson Crossrod 

50.5 gal/wk 49.5 gallwk 50% Carbon Adsorption Resulcs from purchase records 

mreviations: OTVD = Open Top Vapor Oegreaser, CVD = Conveyorized Vapor Degreaser, CND = Conveyorized Non-boiling Degreaser, Opday = Day degreaser is 

in operation, wday = work~ng day, CT = Cold Trap, FR = Freeboard Ratio lb/tov = pounds of solvent emitted per ton of parts degreased, WKLD = work toad, 

1.I.l= mthyl chloroform, Tri. = trichloroethylene, Perc. - perchlorwthylen~. 

'7he appendix of the Dow Report describes each test in detail. 
A.2 EPA COLD CLEANER TEST REPORT 

TEST REPORT 

EVAPORATIVE EMISSIONS STUDY ON COLD CLEANERS 

Walter Pel 1 etier 

Peter R. Westlin 

U. S. ENVIRONMENTAL PROTECTION AGENCY 

Office of Air Qua1ity Planning and Standards 

Research Triangle Park, North Carol ina 2771 1 

May, 1977 
A.2 EPA COLD CLEANER TEST REPORT 

TEST REPORT 

EVAPORATIVE EM1SS IONS STUDY ON COLD CLEANERS 

Walter Pel 1 etler 

Peter R. Westlin 

U.S. ENVIRONMENTAL PROTECTION AGENCY 

Office of Ai r Qua1ity Planning and Standards 

Research Triangle Park, North Carol ina 2771 1 

May, 1977 
SUMMAKY 

A prel iminary study of coi d c1 eaner sol vent kn~i ssions was undertaken, 

the purposes of which were to quantify hydrocarcon sol vent evaporation 1osses 

from typical ai r-agi ta tea, p~iiipagittiteci, iind unac;i tatxi ccld c1 eaners ; and 

to establish relationships between eviiporation rates and several controlled 

test parameters. These parameters included solvent volati 1 i ty, room draft 

velocity, freeboard ratio, and cold cleaner opei at'on. 

desul ts of these tests indicate that i-,i ghly volati 1e solvents, such as 

.~orcnloroethyIene, used in different types of ~oicicleaners with different 

types of solvent agitaticn produce conparable evaporation rates. Solvents 

EK-;;ions from air-agi tated, purng-agi tated, and unagi tated urli ts showed similar 

tes t results ~ithperchl~roet~lylene as the solvent. Mi th less volatile 

sc;vents, such as Minerai Spirits, agitated ccld cleaners showed significantly 

2 3ater solvent emissions than did the una~itated. In addition, these test 

resuits demonstrate a tendency for solvent emis.sions to iricrezse as the room 

*raft velocity is increased. Closing the cover on a cold cleaner drastically 

reduces solvent emissions as is also shown in these tests. 

An increase in solvent emissions with a decrease in freeboard ratio in 

unagitated units is indicated by these test rerults. Also indicated is an effect 

ori sol>snt emissions caused by the shape of the solvent-to-air interface area 

~f unag; tzted tanks. For these tests, a square solvent-to-air interface surface 

reshi ted in greater solvent emissions than did a rectangular one. This result 

may be affected by the orientation of the tank lo the room draft air movement. 

"he effect of solvent volatility on evaporatioc rates is shown as increased 

* o;atility produces increased solvent emissions. The largest difference between 

sdl ~entemisbion rates is shown between tests with the highly volatile, 

relatively pure perchloroethylene and the mineral spirits mixtures. 
TABLE OF CONTENTS 


Page Kc:. 

I. INTRODUCTION ................... 1 


11. EQUIPMENT AND SOLVENTS .............. 1 


I11. TESTPROCEDURES.................. 2 


IV . DISCUSSIONOF RESULTS ............... 5 


Appendix A: Test Data ............ 16 


Appendix B: Solvent Analyses ........ 21 

I. INTRODUCTION 

The Emission Measurement Branch of the Emission Standards and 

Engineering Division undertook, a laboratory study of cold cleaners used for 

parts degreasing. The Furpose of the study was twofold: first, to quantify 

hydrocarbon solvent evaporation losses from typical ai r-agi tated, punp-agi tated, 

and unagitated cold cleaners; and second, to establish relationship between 

evaporation rate and several test parameters including sol vent vol ati 1i ty, 

room draft velocity, and free-board ratio. 

In this preliminary study, a minimum number of data have been collected. 

In most cases, each data value represents only one test run, the curves are 

plotted with only two or three points, and compari sons are made based on only 

two or three test runs. The results included in this report should be regsrded 

as prel iminary and, at best, only indications of trends that can occur with cold 

cleaner solvent emissions. 

The tests were conducted at the IRL laboratory under controlled corditioiqs. 

Four different cold cleaner models were used for this study: an ai i-osi Wed 

Kleer-Flo model 90 uni t, a pump-agi tated Gray Mil 1 s model 500 cleaner, a Kl zerFlo model A-15 unagi tated unit, and a Gray Mil 1s model SL-32 unagi tated cleaner. 

The four different solvents used for these tests were perchloroet:;: --7.2, ,0? 

mineral spirits, 112 mineral spirits, and 140 mineral spirits. 

The results are expressed in milliliters of solvent lost per hour per 

square meter of surface area (ml/hr . m2 ) and in grams of solvent ;ost per hour 

per square meter of surface area (g/hr . m2 ) . These data are used to develop 

curves displaying the re1 ati onshi ps between evaporation rate and the test 

parameters. 

11. EQUIPMENT AND SOLVENTS 

A schematic of the Kleer-Flo model 90, an air-agitated co:d cleaner, is 
2 


shown in Figure 1. The air for agitation was supplied by an industrial 

compressor, and the rate of air injection was set at a relatively constant 

4 to 5 liters per minute with the use of a calibrated orifice meter. A1 though 

not used in any calculations, the air injection temperature was monitored with 

a dial thermometer. 

The pump-agitated cold cleaner used in these tests was the Gray Mills 

model 500 unit. This unit was connected to a timer-switch set to run the pump 

agitator for 20 minutes out of every 65 minutes in a repeating cycle for all 

test runs. This was done to avoid over-heating the solvents and to more 

real is tical ly represent the operation of the cleaner . 

Tests of unagi tated cold cleaners were performed using two different sized 

units. One was a Kleer-Flo model A-15 shown in Figure 2. The other cleaner 

was a Gray Mills model SL-32. Calibrated thermocouples were used to measure 

solvent temperature and ambient temperature for these test runs as well as for 

the other test runs. 

111. TEST PROCEDURES 

The measurements made for each test included solvent volume, room and 

solvent temperatures, room draft velocity, and sol vent densi ty . Temperatures 

were measured with chrome1 -a1 umel thermocouples cal i brated at the water-ice 

point and at water boiling temperature corrected for barometric pressure. Recorders were used to monitor these temperatures over an extended period of 

time. The temperatures reported in this report represent runs averages that 

have ranges of about -+ 5'~. Accuracy of the measured values is estimated at 

Room draft velocity was measured with an A1 nor thermo-anemometer he7 d 

30 cm above the top of the tank. The measurements are estimated to have a 

-

+ 10 percent accuracy for draft velocities above 30 m/min while below this 


5 

level, the accuracy falls to about - + 20 percent. 

Solvent density was determined gravimetrically before and after each 

test run. Solvent volumes were measured with calibrated containers. Accuracy 

of these measurements is estimated to be about - + 2 percent. Samples of solvents 

were collected for analysis of distil lation characteristics and volati 1 i ty. 

These data are shown in Appendix 6. 

Prior to initiation of the test, the cold cleaner units were partially 

filled with solvent and operated, if applicable, for a short period. This 

conditioning step filled any reservoirs with solvent. After the cleaner was 

drained, a measured amount of solvent was placed in the cleaner and the test 

conditions were set as desired. Draft velocity was maintained with a laboratoryhood exhaust fan and small, caged, portable fans. At the end of the test period, 

the solvent was drained from the cold cleaner in the same manner as was completed 

earl ier . The volumes were measured wi th cal i brated containers and t~e volumes 

were recorded. Test conditions such as solvent temperature, ambient temperature 

and humidity, and other test parameters were recorded. 

IV. DISCUSSION OF RESULTS 

Tables 1 and 2 show the results of tests with the air-agitated and pumpagitated cold cleaners, respectively. The test data for the two un~si tated units 

are shown in Tables 3 and 4. Figure 3 shows a plot of the relationship between 

evaporation rate of perch1 oroethyl ene and room draft vel oci ty for these cl caners. 

The scatter in the results shown on this figure indicates that the Type of cold 

cleaner and the agitation method have little effect on the evaporation rate of 

a highly volatile solvent such as perchloroethylene. One result that is evident 

is that the evaporation rate of solvent increases with an increase in room draft 

velocity for all types of cleaners. The data show that for the air-agi tated unit, 
TABLE I. EVAPORATION XATE TEST RESJLTS FOR THE 

AIR-AGITATED COLD CLEA;.lIriG UYIT 

Cover 

Room 

Draft 

Evapsration 

Rate 

Evrlpoimat:on

Ra :e 

Sol vent 

t crchloroethylet~e Opon 27 cl .5 99: 

Percnloroethyl ene Cpen 85 ;756 2846 

??rchloroethyl ene Cl osed 83 143 23: 

-'_: Minera'l 

S,ji 1-its Open 

140 Minera'l 

Spi ri ts Open 

;4C Mineral 

Spi ri ts Open 
TABLE 2. EVAPORATION RATE TEST RESULTS FOR THE 

PUMP-AGITATED COLD CLEANING UNIT 

Sol vent 

Room 

Draft 

(n/iiii n) 

Evaporation 

Rate 

jml jhr . m ) 2 

Evaporatf on 

Rate 

(g/hr . m ) 2 

Perchloroethylene 64 1167 1891 

Perch1 oroethyl ene 28 464 751 

Perch1 oroethyl ene N o 27 

Agitation 

102 Mineral 

Spi ri ts 

140 Mineral 

Spi ri ts 
TABLE 3. EVAPORATION RATE TEST RESULTS FOR AN 

UNAGITATED COLE CLEANING UNIT 

GRAY MILLS M03EL 5L-32 

(3irnensions: 81 cix x 41 crn x 25 cm 3eep) 

(Freeboard Ratio = Freeboard Height, 41 I 

Sol vent 

Freeboard 

2ati o 

Room 

Draft 

(r/rnin ) 

Evaporation 

Xa te 

(ml/hr . rn2) 

Evaporation 

Rate 

&/nr . m ) 2 

Perchloroethylene 6-27 1873 

Perchl oroethyl ene 0.50 1311 

Perchl oroethyl ene 0.29 89 

Perchl oroethyl ene 0.92 12 

102 Mineral 

Spi rtts 0.5G 109 

102 Mineral 

Spi ri ts C. 25 7 

102 Mi neral 

Spi ri ts 0.50 6 

140 Mineral 

Spi ri ts 2.25 8 

140 Mineral 

Spirits 0.53 3 
TABLE 4. EVAPORATION RATE TEST RESULTS FOR AH 

UNAGITATED COLD CLEANER 

KLEER- FLO MODEL A- l 5 

(Dimensions: 33 cm x 33 cm x 32 cm Deep) 

(Freeboard Ratio = 

Freeboard Height ) 33 

Evaporation Evaporation Room Rate Rate 

Freeboard Draft 

Sol vent Ratio (m/mi n ) (m1/hr . rn2) 

Perch1 oroethyl ene 0.20 58 1508 

Perchloroethyl ene 0.42 53 1210 

Perchloroethylene 0.20 3 88 

Perchloroethyl ene 0.42 3 20 

Perchloroethylene 0.74 3 27 

102 Mineral 

Spi ri ts 

102 Mineral 

Spi ri ts 

102 Mineral 

Spirits 0.42 3 27 

102 Mineral 

Spi ri ts 0.74 3 24 

140 Mineral 

Spi ri ts 0.20 3 

140 Mineral 

Spi ri ts 0.42 

140 Mineral 

Spi ri ts 0.74 

the evaporation rate of perchloroethylene increases from about l00C g/hr . m 

2 

at a room draft velocity of 27 m/inin to over 2300 g/hr 2 . K at 85 m/min. Tests 

wi tn the other models showed simi 1 ar results . 

A third test run was made with the $erchlcroethylene in the air-agitated 

cold cleaner with the lid closed. At a draft velocity of about 85 mjmin, the 

evaporation rate with the cover ;pen was over 2800 g/hr . K?, while with the 

mver closed, the evaporat-ian rate was reduced to about 230 g/hr . m 

2 . This 

-?presents Settw than 3 93 percent reduction in e~issions. 

Results of tests with less volatile minerals spirits showed somewhat 

(lifferatt relations hi?^. At roor draft vei~ci ties below 5 m/min, the agitated 

:cl a cleaners showed si yi ficantly greater evaporation rates of mineral spirits 

5.nm sid the unsgitated nodeis. For example, under similar test conditions and 

*oi.llsd:aft veiocities mder 5 m/min, the emissions fro% the air-agitated c~ld 

.i.-.~wzre about 25 g/hr . n2 of 140 ~ineral spirits, the pump-agitated unit 

?m% ;-ns were about 50 g/hr . K', while the unagitated unit emissions were less ,,. 

tk? iO g,'hr . m 2 . Data fron; tests at higher draft velocities are limited, but 

a lirila; result can be shown for the evaporaticn rates of 102 mineral spirits 

at :,C to 60 m/mir, drzft velocity front the puriip-agitated unit and from the two 

unasi ta ted mode: s . 

For these tests freebcard ratio is defined as the height from the surface 

of :he s~lvent tc the top of the tank (freebard heicht) divided by the length 

of the shorter side of the tank. Figure 4 shows the relslionship of the 

evapor~tion rate of perchloroethylene versus freeboard ratio. The figure 

demonstrates the tendency for sol vent eini ssions to decrease as the freeboard 

ratio is increased. 

13 

Figure 5 displays the relat<onship between evaporation rate of variws 

srades 3f Mineral Spirits solvents and freeboard ratio. Solvent l~sses fcr 

tness tests were extremely small and the inherent imprecision in measuring 

thse small differences ?robably account for the lack of clear trends OR this 

figure. One notable resul t demonstrated is that the Kl eer-Flo A-1 5 col d 

cleaner showed greater evaporation losses under the same conditions tha? dfd 

the Gray Mi7 1s cold cleaner. This difference may be due to the differenc~ 

in tnc shape of thc two clnits. The Kleer-Flo model has a square solvent-toair interface area, while the Gray Mills unit has a rectangular (2 2:1 length 

to wfdtt-fi ratio) interface area. These data are normalized as to the solvent 

area, arid the conditions under which these data were conducted were identical, 

so any difference between test results from the two tanks may be because of 

the shage difference. In addition, the Gray Mills tank was oriented the same 

way fw a1 1 tests; that is, the room draft direction was para1 1el with the 

short sides of the tank. Turning the tank so that the room draft direction is 

para7 1e: with the long sides of the tank would 1ikely produce differen: Y* ul is. 

The effect of solvent volatility, in term of solvent initial boilSr5 

temperature, an evaporation rate is demonstrated in Figure 7. For this fiqure, 

an increase in in2tial boiling temperature corresponds to a decrease in sclvent 

volatility. The slopes of the three curves on Figure 7 indicate that evaporation 

rates decrease WI th decreasing sol vent volati 1i ty. The Kleer-Flo A-i5 ,me1 cold 

cleaner was used for these tests. It is not apparent that the square surface 

shape of this unit had any effect on these results. 


P,P?ENJIX A 

TEST GATA 
TABLE A. EVAPORATION TEST RESULTS FOR THE KLEER-FLO MODE1 90 

AIR-AGITATED COL.) CLEAIIER 

(SurXace Area of Agitated Section = 0.398 m2, Total Solvent Surfr.ce Area 2 = 0 974 m ) 

Ave. Ave. Ave. 

Ave. 

Room 

Ave. 

Solvent 

lnjected 

Air 

Injected 

A1r Injected A1r 

Ave 

Room Solvent 

Test 

Run Vo1u:ne Evaporat'on Evaporbtlon 

Run Solvent 

Temp. Moisture 

(x) 

Rate 

(l/min) 

Draft 

(m/min) 

Density 

(glml) 

Time 

(i,rs:min) 

Loss 

(1) 

Rate 

(ml/hr . m2) 

Rate 

(glhr . m ) 

A Perchloroethylene 

Open 

2-A Pr.rchloroethy1ene 

Open 

3-A Perchloroethylene 

Closed 

4-A 112 Mineral 

Open Spirits 

5-A 1:O Yineral 

Open Spiri ts 

6 A 140 Mine.-a1 

Open Spirits 
E (n 

a (n-

-

a, 

os-

>

0 ,l-
a 


E In 3 In- - 3-

0 -I-

'z 
-- 

TABLE D. EVAPORATION TEST RESULTS FOR THE KLEER-FLO MODEL A-15 

UNAGITATED COLD CLEANER 

(Surface Area = 0.109 m2) 

Ave. Ave. Ave. 

Room Solvent Room Freeboard Sol vent Test Run Volume Evaporation Eva?orati011 

Temp. Temp. Draft Ratio Density Time Loss Rate Rate 2, 

Run Sol vent (OK) (OK) (m/min) (g/ml) (hr:min) (1) (ml/hr . m ) (g/h13 . m , - - -

Perchloroethylene 

Perchl oroethyl ene 

Perchl oroethyl ene 

Perchloroethylene 

Perchl oroethyl ene 

102 Mineral 

Spi rits 

102 Mineral 

Spi rits 

102 Mineral 

Spirits 

102 Mineral 

Spi rits 

140 Mineral 

Spi rits 

140 Mineral 

Spi rits 

140 Mineral 

Spirits 
APPENDIX B 


SOLVENT ANALYSES 

UNITED STATES ENVIRONMENTAL PROTECTION AGENCY 

DATE: Nay 4, 1977 

SUBJECT: Analysis of Mineral Spirits and Perch1 orethyl ene 

FROM: R. 3. Jungers, Chief %;ys Source, Fuels, & Molecular Chemistry Section, ACB (MD-78) 

TO: R. Shigehara, OAQPSIEMB (MD-13) 

W. Pel1itier, OAQPS/EMB (MD-13) 

Seventeen samples were submitted to this laboratory on a 

Sample Request and Report Form dated April 21, 1977. Reid Vapor 

Pressure and Distil lation analysis was requested. Distillations 

were run on all but one sample where a specific request was made 

that it not be run. Reid Vapor Pressure was requested and attempted 

oli all samples but only three samples had enough pressure for positive 

measure. This analysis was conducted using the ASTM Method D-323. 

EPA Form 1320-6 (REV 3 76 



Samp1 es of Mi neral Spi ri ts and Perch1 oroethyl ene From EMB . 

Distillation OF 

Sample No. IBP 10% 50% 90% EP RVP LBS. 

S-77-002-602 326 330 352 383 41 5 

-603 332 333 3 53 386 428 

-604 339 340 3 53 383 423 

-605 332 333 351 384 423 

-606 327 3 28 3 51 382 409 

-607 245 245 245 245 286 0.0 

-608 Di sti 1 lation Not Requested 0.5 

-609 322 325 333 359 388 

-610 325 325 333 3 57 392 

S-77-002-639 330 330 342 370 409 

S-77-002-656 369 372 378 393 41 7 

-657 317 327 342 371 41 1 

-658 368 371 379 395 423 

-659 364 371 379 395 423 

-660 369 372 380 394 420 

-661 246 244 24 5 246 286 

-662 246 245 245 246 290 

- - 

-- 

-

3;:-

Q!" 

- tQ 1 :: SA!APLI:IG DATE 1-

0': FIRST IDENT. 8 -. 

0': NO.USED .-. 

0: 

. *-

tpz INDUSTRY -ET.~~~>J,%A~;I?- - (USE TABLE 3 

Q ' G- COhrPANY 

o,: OF 
 ADDRESS

01; - SA16P;ItIG 

METHOD 

DESCRIPTION OF 

IDENT NO SAMPLE OR SAMPLE 

FRACTION 

SAMPLI::G 

CONTRACTOR 

(IF APPLICABLE) 

DATE OF REQUEST 

EPklDU91245 

SOURCE SAYPLE REQUEST L REPORT 

(UUST BE FILLED OUT FOP ELCY TEST 9UR) 

TEST NO-_--

3-71-Q02.~b\ RUN NO--- -

UNIT PROCESS OPERATION 

AIR POLLUTION CONTROL -

FUEL USED 

0 INLET Lj OUTLET 

GAS VOLUME SAMPLED-- .- .---- ---- -- (METER VO; IN FT~) 

SAMPLE ANALYSIS RFGUESTED - GE',EQAL C,7:".'E'iTS 

WT (APPROX C0NCE:TRATIO'IS POSS BLE I:4TtFCE'L',2:S

(SOLID) I (LIQUID) ETC) (IN3ICA:E SFtCcFIC A',ALYSIS 0'; BACnT'D:, 

M G ML 

REQUEST 

PROJECT OFFICER~S~N-TAL. L, REVIE;';ED BY- -

DATE ANALYSIS REQUESTED OAT€ Of REQUEST -

(TO Bi FILLED I'i 2 
- -- - - - 

AIR POLLUTION CONiROL - _ --- .- -

DESCRIPTION OF 

SAMFLE OR SAMPLE 

FRACTIOP 
APPENDIX B. CALCULATIONS 

APPENDIX B 

CALCULA'TIONS 

CONTENTS 

Page 

B.l Degreasing Emission Summary ...................................... B-1 


8.2 Cold Cleaner Emissions .......................................... B-3 


8.2.1 National Cold Cleaner Emissions (1974) .................... B-3 


0.2.2 Emission Rate Per Cold Cleaner ............................ B-4 


8.2.3 Projected Emission Reductions ............................. B-5 


B.3 Open Top Vapor Degreaser Emissions ............................... B-7 


8.3.1 National Open Top Vapor Degreaser Emissions (1974) ........ 8-7 


B.3.2 Emissions Per Average Unit ................................ B-7 


B.3.3 Projected Emission Reductions ............................. B-7 


8.4 Conveyorized Degreaser Emissions ................................. B-9 


8.4.1 National Conveyorized Degreaser Emissions (7974) .......... 8-9 


B.4.2 Emissions Per Average Unit ...........................,'.... B-9 


B.4.3 Projected Emission Reductions .......................'...... 8-9 


B.5 Degreasing Waste Solvent Disposal ................................ B-11 


B.6 Calculations Relating to Adverse Environmental Affects ........... B-13 


9.6.1 Increased Boiler Emissions ................................ B-13 


B.6.2 Sta~ilizers in Chlorinated Solvents ....................... 13-14 


B.6.3 Utilities Consumption of Carbon Adsorbers ................. B-16 


0.6.4 Fuel Costs of Incineration for Manufacturing 

Cold Cleaners .......................................... 8-17 


8.7 References ...................................................... B-18 

3 B.l DEGREASING EMISSION SUMMARY, 1974 (All units = 10 metric tons/yr) 

1. Total Organic Emissions from Degreasing 700 

Col d Cl eaning 380 

Open Top Vapor Degreasing 200 

Conveyorized Degreasers 100 (14%) 

(25 CND & 75 CVD) 

Wiping Losses 20 (3%) 

2. Contribution to National HC Emissions 

Degreasing Emissions (1974) -

- -

700 = 2.5% National HC Emission (1975) 28000 

Degreasing Emi ssions - 700 National HC Emissions from - 17000 = 4.1% 

Stationary Sources (1 975) 

3. Solvent consumption data were collected from several sources and 

tabulated in Table B-1. The consumption estimates were averaged to estimate 

the solvent consumption of each type of degreaser. These data were the basis 

for our emission estimates. 

----- 

B.2 COLD CLEANER EMISSIONS 

B.2.1 National Cold Cleaner Emissions (1 974) 

Given: (a) Gross cold cleaning solvent consumption = 450 Gg/yr* 1974 

(b) about 5% of this is from wiping operations, which are 

not considered cold cleaner (CC) emissions 

(c) about 25 Gg/yr of this is from conveyorized non-Soil in? 

degreasers (CND) . (See subsection B .4.1) 

(d) Waste solvent disposal (WSD) amounts to 280 Gg/yr. 

Approximately 7% of this is incinerated or landfilled in such 

a manner that no emissions occur. (See Section 3.1.4) 

Calculate: Cold Cleaner Emissions Estimate 

450 = Gross cold cleaning solvent consumption 

- 25 = for wiping losses 

- 25 = CND losses -

400 = Cold cleaner emissions if all WSD evaporates 

- 20 = controlled emissions due to proper waste solvent disposal 

380 (+loo) - Gg/yr = estimated emi ssions from cold cl eaners-1974 

*Gs = lOJ metric tons 
B.2.2 Emission Rate Per Cold Cleaner 


Given: (a) 880,000Maintenance cold cleaners (1974) 


340,000 Manufacturing cold cleaners (1974) 


1.22 x lob Total cold cleaners 1974 

(b) A manufacturing cold cleaner has twice the average emission 


of a maintenance cold cleaner. 


Calculate: Individ~al cold cleaner emission rates 


(a) 380 (L1OO' Gglyr = 0.31 (+0.08) - Mgjyr per unit 1.22 x 10b units 


= 660 Ib/yr per unit 

2 100 (+20) - gal/yr per unit 

(b) IF: X = average maintenance cold cleaner emission 

2X = average manufacturing cold cleaner emission 

Ta, = national maintenance cold cleaner emissions 

Ta2 = national manufacturing cold clecmer emissions 

THEN: X x 880 (~10~)
 = Tal . 

2X x 340 (~103) = Tap 

Tal + ia2 = 380 (+loo) - (x103 metric tonlyr) in 1974

AND: Tai = 215 (~10' metric tonlyr) 

3
 Ta2 = 165 (x10 metric tonlyr) 

X = 0.24 metric tonlyr = (4901 b/yr) 

2X = 0.48 metric ton/yr = (980 ?b/yr) 

(c) "Safety Kl een" maintenance cold cleaners and others: 

Let XSk = 3tlerage emission from a Safety Kleen cleaner 

-- aperage emission from other maintenance cold cleaners 


0 


Then: 

'sk -

- 24 r 103 netric tonjyr 0.17 metric ton jsk c1 zansr140,000 = 3813 1h!vr 

Y, = 203-L4 0 880-140 = 0.24 metric ton= 530 lblyr 
B.2.3 Srojected Emission Reductions* 

A. Cold Cleaner System A 

Assumptions & Estimations: 

1. Average typical cold cleaner emits about 0.3 metric tonslyr. 

2. An average of 55% of cold cleaning emissions is due to 

evaporation of waste solvent. This could be reduced to 

10% with excel 1 ent compl iance 

30% with average compliance 

40% wi th poor cornpl iance. 

3. 45% of the emissions occur directly from the cold cleaner. 

20% is through bath evaporation (including agitated & spray 

evaporation) and 25% is throuqh carr.y out. Cover closing can reduce 

bath evaporation from 20% to 4% with excellent compliance 

9% with average compliance 

18% with poor compliance. 

Drainage practice could reduce cavy-out from 

25% to 5% with excellent compliance 

11% with average compliance 

18% with Poor com~liance. 

Conclusion: 

With excel 1 ent compl iance system A could reduce emissions by 100-1 0-4 

80%. With average compl iance, emissions could be reduced by 100-30-9-1 1 = 

50%, With poor compl iance, emissions could be reduced by 100-40-1 4-18= 

28%. 

*The previous and the following projected estimates represent the best engineering 

judgement that can be made aiven the limited data- base. These estimates are 

not to be interpreted as test data; thus., a wide range is given for most 

estimates. 

8- 5 
B. Cold Cleaner System B 

Note that excellent compliance would not vary much between systems 

A and B. 

Assumptions & Estimations--same as for system A except: 

1. Mechanically assisted covers, the "major control device" and 

spray specifications and agitation restrictions are estimated to 

reduce bath evaporation from 20% to 2% with excellent compliance 

6% with average compl iance 

10% with poor compl iance 

Conclusion: 

With excellent compliance system B could reduce emissions by 100-10-25= 

83%. With average compliance, emissions could be reduced by 100-30-6-11= 

53%. With poor compliance, emissions could be reduced by 100-40-10-18= 

C. Cold Cleaners Using High Volatility Solvent 

Recommended controls would effect higher emission reductions on 

units using highly volatile solvents. It is estimated that with average 

compliance emission reduction would increase to 55% for system A and to 

69% for system B. 

Note: Table 3-14 in the Dow Report estimates emissions from a typical, 

maintenance cold cleaner. Although the overall emission rates are on the high 

side, the percentage of emi ssions from waste sol vent evaporation (refi 11ing) , carry-out and bath evaporation calculate to 58%, 28%, and 16% respectively. 

This compares reasonably with the previous estimates of 55%, 25% and 20% for 

a1 1 types of cold cleaners , (considering that manufacturing, cold cleaners 

tend to have a higher proportion of bath evaporation than do maintenance 

cleaners). 
- - 

8.3 OPEN TOP VAPOR DEGREASER EMISSIONS 

6.3.1 National Open Top Vapor Degreaser Emissions (1 974) 

Gross vapor degreasi ng solvent consumption is 275 (225) Gg*/yr. 

Approximately 200 (+20) - Gg/yr of this is from Open Top Vapor Degreasing (OTVD) 

and 75 Gg/yr is from Conveyorized Vapor Degreasing (CVD). These estimates are 

similar to previous estimates that CVD emit about 65 Gg/yr and OTVD, 210 ~~/~r

8.3.2 Emissions Per Average Unit 

1. If there are 21,000 OTVD (1974), an average OTVD would emit about 

200 (+20) - Gg/yr I 21,000 = 9.5 MT/yr . 2 2. If an average OTVD has an open area 18 (+3) ft2 = 1.67 (+0.3) m 

then emission per area would average 5,7 ~~/~r.m'(These averages probably 

are within -+ 25 percent accuracy.) 

B.3.3 Projected Emission Reductions 

Estimates have been made of the total control efficiencies ( + the cont 

efficiencies from improved operating practices () and control efficiencies 

from control equipment (qe) for control systems A and B. 

I System A I System B 

% poor average excel 1ent -poor average excel 1 ent 

15 25 3 5 20 30 40 

qo 

Approx. n+ 1 30 45 60 1 45 60 75 

Note: (1 - n+) = (1 - no) (1 - ve) 

- *Gg = 103 metric tons 
2. Given 9.5 mT/yr per average OTVD, 

Emission Per 

-

uncontroll ed 

unit poor 

Erni ssion per control led u

average excel 1ent 

nit 

(mT/yr ) 

System A 9.5 6.5 5.2 3.7 

System B 9.5 5.3 3.8 2.4 
------------- 

8.4 CONVEYORIZED DEGREASER EMISSIONS 

B.4.1 National Conveyorized Degreaser Emissions (1 974) 

Given: (a) Emissions from conveyorized vapor degreasers (CVD) is 

(b) It is estimated that between 25 to 35 percent of the 

conveyorized degreasers are Conveyorized Non-Boiling Degreasers 

(CND).8 This estimate appears somewhat high, thus choose 25 percent 

which is on the lower end of the range, 

Cal cul ate : 

(a) CND emit 25 Gg/yr 

(b) CVD emit 75 Gg/yr 

(c) Total conveyorized degreaser emission are 100 Gg/yr. 

B.4.2 Emissions Per Average Unit 

1, Estimate that there are about 3170 CVD and 530 CND nationally in 

1974.~''~ 

2. An average emission rate for a CVD would be 75 000 M 3hAE ,23.7 ,,,T/yr

3, Average emission from a CND would be .-&- 25 000 = 47.2 MT/yr. 

9.4.3 Projected Emission Reductions 

Estimates have been made of total control efficiencies (n,), the control 

efficiencies from improved operating practices (so) and the control efficiencies 

from control equipment for control systems A and B. 

operation Improved I 20 

25 

30 

Control I System A 

Efficiencies Compl iance : 

(d(%) ) poor average excel lent 

1 

System B 

Compl iance : 

poor avg. excl . 

Control 

equi pment 

Total 

approximated 

Note: (1-n+) = (1-no) (1-ne) 

*~g= lo3 MT B-9 
2. Emission control for typical units: 

Emission rate (MT/yr) 

Control 1 ed with Control 1 ed with 

Uncontroll ed System A System B 

Conveyorized Vapor Deg. 

Con. Non-boiling Deg. 

Average CD I 27 120 (19 to 21) 1 10 (7.5 to 13) 
-- 

B. 5 DEGREE ING WASTE SOLYENT DIS WSAL 

It has been estimated that 280 (+go) thousand metric tons/yr of waste 

solvent are disposed of by the solvent metal cleaning industry in 1974. The 

calculation is based on the following assumptions and estimates.* 

Assumptions 

1. Percent virgin solvent that becomes waste solvent for each category 

of degreasers. (EPA and Dow Chemical estimates) 

a. Degreasing industry col lectivel y 30% to 50% 

b. Cold cleaners col lectively 45% to 70% 

c. Maintenance cold cleaners 50% to 75% 

d. Manufacturing cold cleaners 4G% to 60% 

, e. Conveyorized vapor degreasers 10% to 2rl% 

f. Open top vapor degreasers 20% to 25% 

2. Virgin solvent consumption. (EPA estimates) 

a. Cold cleaners (excluding 10% as wiping losses) 

Maintenance (56%) 21 5,000 Mtlyr 

Manufacturing (44%)" 165,000 Mtlyr 

b. Open top vapor degreasers 200,000 Mtlyr 

c. Conveyorized degreasers (vapor and col d) 100,000 Mtlyr 

Waste Solvent Estimates 

1. Maintenance col d cl eaners = 134,000 Mt/yr 

(or 21 5,000 x .625 = 134,000 Mtlyr) 

2. Manufacturing cold cleaners = 83,000 Mtlyr 

(165,000 x .50) 

3. Conveyorized vapor degreasers = 15,000 Mtlyr 

(100,000 x .15) 

*me accuracy of the estimates is not expected to be better than + 30%. -
4. Open top vapor degreasers = 45,GOG Mt/yr 

(200,000 x .225) 

Total wastc s~lvent = 277,0@0Mt/yr(~85,00C Mt/~r) 
E.6 CALCULATIONS RELATING TQ ADVERSE ENVI2ONMENTAL EFFECTS 

8.6.1 Increased 6011 er Emi ssions-Computation 

The objective is tc determine the magnitude of increased boiler emissigns 

caused by use of a carbon aosorber. The carbon adsorber generally has the 

highest energy consumption compared to that of other control devices. A 

typical carbon adsorber could be a Vic #536 AD. According to the J. L. Thom?son 

test report by Dow, the steam usage may be 113 lb. per desorption cycle which 

converts tc 113,000 Btulcycle. Taking an averaTe of two desorption cycles 

per day, the consumption becomes about 225,000 Ptulday or 28,000 Btulhr. 

Assume that high sulfur fuel oil were to be used t o f i r e the boiler. Take 

residual fuel oil with 2% sulfur content. According to "Compilation of Air 

Pollution Emission Factors" (AP 42) such fuel combustion would em it the followinq 

3 pollutants per 10 gal. fuel oil : 310 lb SO2, 23 lb particulates 60 lb NG,, 

4 1 b CO and 3 lb HC (hydrocarbons) ; 

Relate the emissions to an hourly emission rate. To produce 

at 75% conversion efficiency would require 37,000 Btu/hr of fuel. Choosing 

#5 fuel oil , we have 148,000 Btu/gal . Thus ,; increased fuel consumptian . -. would-=. 1t


be about 0.25 gal/hr.* Increased pollutant emission would then be 0.08 1t/hr 

(0.036 kglhr) SO2, 0.005 1b/hr (0.002 kg/hr) particulates, 0.008 lb/hr 

(0.00035 kg/hr) NOx, 0.0005 lb/hr (0.0002 kg/hr) CO and 0.0004 1b/hr 

(0.0002 kg/ hr) HC. 

Com~are the increased e~issions to the enissim reduction caused by the 

carbon adsorber. A typical adsorber system that is properly designed and 

maintained may save 50 gal/wk 5 15 lb/hr = 6.8 kg/hr. Thus, the total increased 

hiler emissions equals ~b.out 0.6% of the mission reduction caused by a typical 

carbon adsorber. 
E.6.2 Stabilizers in Chlorinated S~lvents 


Tri chl oroethyl ene 


Epichlorohydrin 


Butylene Oxide 


Gl.yci do1 


Acryloni triie 


Dii soprop.yl amine 

Triethyl mine 


Ethyl Acetate 


Diisobutylene 


T hymo i 

N-Methyl Pyrrol e 


Acetal dehyde 


Dimethyl 


Hydrazone


Tetrahydrofuran 


Sec. Butanol 


N-Propanol 


1 ,I ,I Trichloroethane 


1,2 Butylene Oxide 


Butyl ene 


Ni troethane 


N i t.rome thane 

3-&thoxy 


Propronitri le 


1,3-Dioxol ane 


1,4-Dioxane 


N-Methyl-Pyrrole 


To1 uene 


Methyl Ethyl 


Ketone 


Isobutyl Alcohol 


Tertiary Butanol 


Sec. Butanol 


Acrylonitrile 


Acetonitrile 


Isopropyl Ni t ra te 


Tertiary Amy1 


A?cohcl 


l,3,5 Trioxane 


2: 

;O Fish 


Solubility Toxicity BOD-2C Boilinq Point 
 C P in water PPm % of Theory L s

1C 


ncn-rnisc. 


10 


1 C)G 

100 


S 


27-37 


10 


s2G 

13 


190 


parti a1 1y 


S 


= slihtlyd s. = soluable 'concentraticn giving 50% fatality to rats - o r9 human when feed orally, i.e. LD 5C. i 
-- 

% Fish 

Solubil i.ty Toxicity BOD-2Q Soilinq Point 

in water PPm

----. 

% of Theory "C 

Methylene Chloride 

Propylene Oxide 

Butylene Oxide 

Amy1 ene 

Cycl ohexane 

Methyl ene Chloride 

Perch1 oroethyl ene 

Thymo1 S1 .S 

4-Methyl 

Morphol ine 100 2700' 

P-Tertiary Amvl 

Phenol 

3-N-Fropoxy partially 31 00' 

Propionitrfle 

Isopropyl A1 coho1 

Epi chlorohydrin 

niall yl amine 

Estimated Stabilizer Emissions into Sewer 

. --

% 

Stabilizers in Approxi mate 

Solubility Sewer Erission Rat. 

Solvent blend % gal /wk +/wk 

Worst Case: 5'% 40% 1 .C) 0.004 

nversge Case: 

Atmcspheric Ernissi~nReducti 

Typical Emiss'on Control : 50 galiwk 0.2 3 

n /w 
6.6.3 UTILITIES CONSUMPTION OF CARBON ADSORBERS 

Reference to Model Ventilation Rate Sol vent Water Steam 

Dow Report Adsorber Both Beds Adsorbinq Recovered Consumption Consumption El ec ricity 

Appendix : Test Site Vic # (cfd (qal/wk) (103 gal/yr) (106 Btulyr) (105 kw) 

C-10 Vic Manuf. Co. 572AD 5500 70 6 30 310 30 

C -8 Super Radiator Co. 554AD 23000 * 1380 380 30 

C -9 J. i. Thompson Co. 536AD 940 25 to 50* 2 30 54 4 

C-11 W. Electric Co. 536AD 21 300 85 1380 520 13 

Average 2700 900 320 19 

*Defecti ve control systems 
B .6.4 Fuel Cost of Incineration for Manufacturing Coi d Cleaners 

I Assume a ventilation rate of 50 cubic ft/rninute/ft 2 of open top area, 

an average tank area of 6 ft2, 8 hours of operation per weekday and 2 112 

dollars/million BTU fuel cost. Using an air density of 0.075 1 bslft 2 , a 

specific heat of 0.25 BTU/lbs°F for ai'r, and a maximum temperature of 800°F, 

an approximate annual fuel cost would be about $1200/year, as sumarized 

be1 ow. 

Exhaust volume = 30S cfm x 60 min/hr x 8 hrlday x 240 day/yr = 35 x 106 

ft /yr 

Heat required = 35 x lo6 ft3 x 0.075 1b/ft3 x 0.25 BTU/lb°F x 740°F = 

485 x lo6 BTU/yr 

Annual fuel cost = 485 x lo6 BTU/yr x 2.50 $11o6 BTU = 121 5 1200 $/yr 
B, 7 REFERENCES 

1. Information provided by Tom Hoogheem, Monsanto Research Corp. , Dayton, 

Ohio, by telephone to J. C, Boll inger, EPA, on December 1 and 6, 1976. 

2. Surprenant, K. S. and Richards, D. W. of Dow Chemical Company, "Study 

to Support New Source Performance Standards for Solvent Metal Cleaning 

Operations," 2 vol., prepared for Emission Standards and Engineering 

Division (ESED), under Contract # 68-02-1329, Task Order #9, June 30, 1976, 

pp. 7-3. 

3. Ibid, 

4. Kearney, T, J,, Detrex Chemical Ind., letter to J. C. Bollinger, EPA, 

January 9, 1976. 

5. Information provided by J. S. Gunnin, Shell Chemical Co., Houston, by 

telephone to J, C, Bollinger, EPA, September 16, 1976. 

6. Op. Cit., Surprenant, K, S., pp, 7-3, 

7. Boll inger , John C. , "Trip Report - ASTM, Consultant and Two Waste Sol vent 

Plants," memo to David R. Patrick reporting on trip to ASTM D-26 meeting 

of January 26, 1977. 

8. Boll inger, J. C., "Maximum Impact of NSPS on 1985 National Degreasing 

Emissions," December 1975. 

9. Ibid. 

10. Surprenant, K. S., Op. Cit. 

11. Ibid. pp. 7-3. 
-- - 

TECHNICAL REPORT DATA 

(Plcose read Irtwcliot~s011 llrr revcrsr before cornplc~rrr~) 

. REPORT NO. 12. 13. RECIPIENT'S ACCESSIONNO. 

EPA 450/2-77-022 I . TITLE AND SUBTITLE 15.REPORT DATE 

Control of Volatile Organic Emissions from November 1977 

Sol 6. PERFORMING ORGANIZATION CODE vent Metal Cleaning 

. AUTHOR(S) 8. PERFORMING ORGANIZATION REPORT N 

John C. Bollinger* 

Jeffrey L. Shumaker, ESED OAQPS 1 .2-079 

PERFORMING.ORYANIZATl0N NAME AND ADDRESS 10. PRClGRAM ELEMENT NO. 

U. S. Environmental Protection Agency 

Office of Air and Waste Management 11. CONTRACT/GRANT NO. 

Office of Air Quality Planning and Standards 

Research Triangle Park, North Carolina 27711 

2. SPONSORING AGENCY NAME AND ADDRESS 13. TYPE OF REPORT AND PERIOD COVERE 

14. SPONSORING AGENCY CODE t---


1 

5. SUPPLEMENTARY NOTES 

*No longer with EPA 

6. ABSTRACT 

This report provides the necessary guidance to control emissions of 

volatile organic compounds (VOC) from solvent metal cleaning operations. 

Emissions are characterized and reasonably available control technology (RACT) 

is defined for each of the three major categories of solvent metal cleaners: 

cold cleaners, open top vapor degreasers, and conveyorized degreasers. 

Information on the cost of control, environmental impact and enforcement 

issues is also included. 

7. KEY WORDS AN0 Dl CUMENT ANALYSIS 

DESCRIPTORS I ~.IDENTIFIERS/OPEN ENDED TERMS -

9ir Pol lution Air Pollution Controls 

Solvent Metal Cleaning (Degreasing) Stationary Sources 

Emissions and Controls Organic Vapors 

qegulatory Guidance Degreasing 

9

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