VOC
EmissionControl

Ministry of the Environment
Japan Industrial Conference on Cleaning
Asahi Research Center Co., Ltd.

VOC Emission Control by cutting costs and work
environment improvement activities
Voluntary measures manual regarding industrial cleaning●Why VOC emission control is necessary / Outline of this manual ............................p1●Viewpoint of this manual ............................................................................................p2●How to use this manual ●Quantitative measurement experiment to indicate emission control effectColumn What is VOC?

●Why does loss of cleaning agent (solvent) occur?....................................................P4●Evaporation and condensation ●Role of cooling coils●Summary of VOC emission control technology.........................................................p6●3-tank type cleaning system ●Checking factors of VOC generation ●Flowchart of VOC emission control

Improvement of cleaning process Procedure of start-up/stop ............................................................................................p8
 Reduction of airstream around the cleaning equipment ..............................................p9
 Change in local emission method ...............................................................................p10
 Examination of Dwell method (let the items dry above the vapor zone) ....................p11
 Reduction in amount of liquid taken out by items being cleaned .................................p12
 Installation of lids/cover ..............................................................................................p13
 Proper cooling effect ...................................................................................................p14
 Securing free board ratio ............................................................................................p15
Introduction of alternative cleaning agent

 Hydrocarbon type cleaning system ............................................................................p16
 Semi-aqueous type cleaning system .........................................................................p17
 Water type cleaning system .......................................................................................p18
Introduction of retrieval/recycling equipment

 Retrieval/recycling equipment by cryogenic condensation ........................................p19
 Actual cases of retrieval/recycling equipment by cryogenic condensation ...............p20
 Retrieval/recycling equipment by activated carbon adsorption .................................p23
 Actual cases of retrieval/recycling equipment by activated carbon adsorption .........p24
Airtight cleaning equipment
 Depressurized steam cleaning system ......................................................................p25
 Completely airtight cleaning equipment .....................................................................p26
Reference Main regulations applied to chloride solvent .................................................p27
Appendix Actual quantitative measurement experiment raw data, actual quantitative
measurement experiment chart, committee members register ......................................p28
Websites with related information

Japan Industrial Conference on Cleaning

Ministry of the Environment, VOC related website

Ministry of Economy, Trade and Industry
VOC related website

Why VOC emission control is necessary / Outline of this manual
Reasons why VOC emission control in industrial cleaning is needed
In the Amended Air Pollution Control Law implemented in April, 2006,
1) Facilities larger than a certain size come under the regulation and are required to makereports to the prefectural government2) Facilities that come under the VOC emission control regulation are required to comply
with the emission concentration standard at exhaust vents
3) Facilities too small to come under the VOC emission control regulation are entrusted totake voluntary measures
This is based on the idea of effective VOC emission control by a proper combination(Best Mix) of legal regulation and voluntary measures by the industry.
In particular, many of small and mid size business offices with industrial cleaning sites
are exempt from the regulation as is shown in 3), therefore it is crucial to take widemeasures for VOC emission control and to conduct voluntary VOC emission control
measures.
The target time limit for achieving the figures of VOC emission control in the Amended
Air Pollution Control Law is in FY2010, business offices (fixed sources) are to reduce VOC
emission by 30% from the figures in FY2000.
Amendment of the law is planned whether if this aim has been achieved in FY2010 ornot. Depending on the result of amendment, facilities subject to the regulation can bereviewed.

Outline of this manualThis book is a manual of VOC emission control measures in industrial cleaning and is bothas quantitative and as simple as possible. The aim is to put concrete VOC emission control
measures into practice based on this chart.
Compiled chart of VOC emission control measures in industrial cleaning

Operation
improvementConcrete method
・Procedure of start-up/stop
・Reduction of airstream
around the cleaning
equipment
・Examination of Dwell method
・Reduction of amount of liquidtaken out by the items being
cleaned・Change of local emission
methodCleaning
equipment
improveme
nt

・Installation of lids/cover・Proper cooling effect・Securing free board ratio

Introduction ofalternative
cleaning agent
Introduction or
retrieval/recyclin
g equipment
Airtight
equipment

・Water type, semi-aqueous
type, hydrocarbon type,
halogen (fluoride, bromide),etc, cleaning agent
・Activated carbon adsorption
method・Cryogenic condensation
method・Depressurized steam
cleaning system
・Airtight cleaning equipment

Approx. 60 – 90%
Quantitative measurement experiment data

Cleaning process improvement

Type ofmeasures

VOC emission control
effect(Note: confirm details)

Initial cost required
for the measures
Zero

Samples ofcost cutting (byreducing
cleaning
agent)-(refer to model cleaning
equipment data p.9)

About ¥100,000¥27,000 –44,000/month(refer to model cleaning
equipment data p.11)

Zero¥2,000 –18,000/month(refer to model cleaning
equipment data p.12)

About ¥10,000¥10,000/month(refer to model cleaning
equipment data p.10)

0 - ¥1milion¥22,000/month(refer to model cleaning
equipment data p.13)¥10,000 – 500,000¥15,000/month(refer to model cleaning
equipment data p.14)¥100,000 – 1million¥1,400/month(refer to model cleaning
equipment data p.15)

Less than ¥1million¥1,000/month

Approx. 15– 80%
Approx. 80%

Approx. 70 – 85%
Approx. 80%

Approx. 10 – 30%
Approx. 20%
100%(emission of alternative
substance not included)

Several tens of
million yen (replacing
equipment)

60 – 80%

Several million 20million yen

70 - 80%

Several million –20million yen

1Viewpoint of this manual

How to use this manual
Full scale environmental policy on VOC emissions control has started (implemented on April
1, 2006).
VOC emission control in industrial cleaning from the viewpoint of air pollution prevention
sets its target at non-water type cleaning agents, of which chloride cleaning agent makes up
70% (fig.1). These non-water type cleaning agents, especially chloride solvent, are required
to come under chemical substance management including legal regulation on cleaning for
not only air pollution but also work environment, waste, underground penetration, waterpollution (reference material). This manual organizes VOC emission control technology
mainly for chloride cleaning agent, and gives explanation to ease voluntary VOC emission
control measures matching the actual situation for business offices.
Oil refinery, oil tank
5%

Gasoline stations
8%
Cleaning
2%
Rubber products
2%

Chemical
Total VOC
products emission in Japan8%
1,500 (in thousand
Industrial
cleaning
agent
9%

tons/year)

Adhesive
5% Printing
ink
5%

Other VOC
34%
Paint
56%

Methylene
chloride
Industrial cleaning 34%

VOC emission 141(in thousand
tons/year)
Tetrachloro
ethylene
9%

Trichloro
ethylene
23%

VOC emission inventory in fiscal year 2000
(Center for Environmental Information Science 2003)

Cost cuttingWork
environment
improvement

VOC Emission Control
VOC emission control measures in industrial cleaning are generally organized in the “VOC
emission control organization chart” (P.1). While introducing retrieval/recycling equipment ofcleaning agent vapor is an effective measure, low-cost technology measures for
improvement of cleaning process (improvement of operation, modification of cleaning
equipment) are also effective as well as being simple.
In addition, VOC emission control measures are environmental measures, at the sametime they directly lead to emission control in cleaning process/reduction of cleaning
agent purchase amount by retrieval and recycling, resulting in cost cutting measuresin the process. Also VOC emission control measures improve the working
environment.
Improvement of cleaning process means low-cost technology measures. Depending on
the method of improvement used, a considerable emission control effect can be attained.
Synergy can also be expected by combining improvements.
Your creative ways and means can achieve VOC emission control resulting in cost cutting
and work environment improvement.
2Viewpoint of this manual
Quantitative measurement experiment to indicate emission control effect

Quantitative measurement experiment data to indicate the effect
In “Improvement of cleaning process” in this manual, there is quantitative measurement
experiment data on each type of emission control technology from actual measurement andanalysis at a model cleaning equipment actually using methylene chloride.
The experiment was conducted over a period of one year. The result is modified after
measurement in consideration for conditions such as outside temperature, etc, as much as
possible. However the cleaning equipment used in each individual facility varies greatly.
Therefore use the data and figures of this model cleaning equipment as a quantification ofrelative evaluation, not as the absolute value of effect.
Specification and measurement condition of model cleaning equipment for quantitative
measurement experiment
Soak cleaning tank (firsttank)
Rinsing tank (secondtank)Steam cleaning tank(third tank)
Vapor zone
Model cleaning
equipment outerdimensions

Height
(mm)

width
(mm)

Depth
(mm)

350

370

340

380

370

340

-

370

340

520

1360

420

1210

1940

950

Cleaning agent in use: methylene chloride(dichloromethane)Amount of cleaning agent in the equipment:
approx. 150kg
VOC emission rate is measured by the liquidsurface in the stable steam cleaning tank inoperation. The rate is calculated according to therise and fall of cleaning agent in liquid form.
The published data is modified as values in room
temperature of 20°C and standardized.

VOC emission control effect of each item in “Improvement of cleaning process” is basedon the quantitative measurement experiment data. The cost-cutting effect in the graph(yen/month) is calculated on the assumption of operating 8 hours/day, 25days/month, withthe unit price of methylene chloride assumed as ¥200/kg.

Appearance of model cleaning equipment forquantitative measurement experiment

ColumnWhat is VOC?

Transport equipment with model cleaning equipment forquantitative measurement experiment(Source: Industrial Cleaning VOC Manual Committee WG)

VOC (volatile organic compound) is a general term fororganic compounds which are volatile and evaporate into
gaseous form in the air.

In the definition of Article 2 of the Air Pollution Control Law, it states “organic compounds which are in gaseous
form when emitted or dispersed into the air from the emission vent”. It does not give a clear answer to “Is thesubstance we use in our company legally classified as VOC or not?” As for the 8 excluded methane and Freoncompounds which are considered to have little or no photochemical effect, their names are indicated in a
separate government ordinance (May 27, 2005, Government Ordinance No.189, Article 2-2).
The main VOCs are used in paint, printing ink, adhesives, cleaning agents, etc, and can be generally
considered as “organic solvents”. Typical VOCs actually used in factories in Japan include toluene, xylene,
ethyl acetate, methanol, methylene chloride, etc. Approximately there are 200 substances. In the industrial
cleaning field, most cleaning agents are defined as VOC such as chloride type, hydrocarbon type, glycol ether,alcohol, etc. However, surfactant is not VOC, nor is water type cleaning agent.

Substances designated as non-VOC excluded substances
1) methane2) chlorodifluoromethane (HCFC-22)
3) 2-chloro-1,1,1,2-tetrafluoromethane (HCFC-124)
4) 1,1-dichloro-1-fluoroethane (HCFC-141b)5) 1-chloro-1,1-difluoroethane (HCFC-142b)6) 3,3-dichloro-1,1,1,2,2-pentafluoropropane (HCFC-225ca)7) 1,3-dichloro-1,1,2,2,3-pentafluoropropane (HCFC-225cb)
8) 1,1,1,2,3,4,4,5,5,5-decafluoropentane (HFC-43-1 0mee)

3Why does loss of cleaning
agent (solvent) occur?
Evaporation and condensation

Total amount of cleaning agent in liquid formin the equipment (kg)

Cleaning agent in the cleaning equipment repeatedly evaporates (in gaseous form) and
condenses (in liquid form). The chart shown below is a record of change of the total amountof the cleaning agent in the cleaning equipment (without any items being cleaned, in static
condition) actually measured in the model cleaning equipment for a quantitative
measurement experiment. Loss of cleaning agent occurs even while the cleaning operationis stopped. Cleaning agent vapor, which is heavier than air, diffuses from the opening of the
top of the cleaning equipment. Generally speaking, factors of loss in cleaning agent are thisvapor diffusion, leaking from the equipment, and being taken out by the items being cleaned.
In particular, measures for vapor diffusion are important VOC emission control measures.
9:00 cooling water
ON heater ON

Cleaning agent
increased after
heater was turnedOFF

Cleaning agent
vapor was filled

9:30 Vapor in theequipment was stabilized.
Lid was taken off.

Cleaning agent
evaporation when theequipment was inoperation

Amount of loss
in a day

17:00 Lidwas put

Cleaning agent vapor wascondensed at night, also
diffused from the equipment

16:00 cooling water
OFF heater OFF

Time (h)The above chart shows the amount of cleaning agent in the cleaning equipment in an
actual day without items being cleaned in a model cleaning equipment for a quantitative
measurement experiment. Cooling water and heater is turned ON and the lid was taken off
at 9:00 in order to operate the cleaning equipment at 9:30. Operation was stopped at 16:00,
cooling water and heater turned OFF. The lid was put at 17:00 to finish the work of the day.
The vapor diffused and the liquid amount decreased during the night. This is repeated everyday.
VOC emission

Vapor line
Cooling coil
Vapor zone

HeaterUltrasonicvibrator
Soakcleaning

Rinsing

Steamcleaning(drying)

VPC emission image by vapor diffusion from the cleaning equipment

4

Why does loss of the cleaning agent (solvent) occur?

Role of cooling coil
When cleaning is done with a cleaning agent without flash point such as methylene chloride,
generally steam cleaning is done at the end. The purpose of steam cleaning is listed below:
1) To give a final rinsing with the evaporated, purest cleaning agent2) To heat up the items being cleaned to boiling point to reduce cleaning agent taken out
and shorten the drying time3) To distil the cleaning agent in the cleaning equipment and to circulate pure cleaning
agent
Therefore steam cleaning is an indispensable process in cleaning. For steam cleaning ,the cleaning agent is heated to boiling point in the steam cleaning tank. Some of thegenerated vapor is condensed on the surface of items being cleaned to be used for
so-called steam cleaning. Most of the rest of the vapor is not condensed and remains asvapor. A cooling coil is installed above the vapor zone to cool, condense, and liquefy thevapor.
Cooling coils are long enough to cool a certain height in the vapor zone. The space
above the vapor zone surrounded by the cooling coils is called the cooling zone. Items being
cleaned which have finished steam cleaning are temporarily placed in the right direction in
the cooling zone to let the cleaning agent attached on the surface evaporate and dry.
The most important role of the cooling coil is to cool and condense the vapor generated
in the steam cleaning tank. By condensing the vapor with the cooling coil, the cleaning agent
in the cleaning equipment is condensed as shown below.

Steam

Condensation(cooling coil)Water
separator

Coolingtank

Warmliquid tankSteamcleaning tank

By this circulation, contaminants such as oil, etc, dissolved in the cleaning agent aretransferred to the solvent in the steam cleaning tank for condensation, maintaining the purityof the cleaning agent in the cool liquid tank.
As we have seen, the important effect of the cooling coil is to reduce the amount ofcleaning agent which leaks outside the equipment, by condensing the vapor. Reduction ofcleaning agent leakage leads to reduction in running costs, lowered VOC concentration in
the work environment, and less environmental impact.

Steam pressure [kPa]

Methylene chloride
Trichloroethylene
Tetrachloroethylene

Temperature [℃]5Summary of VOC emission
control technology
3-tank type cleaning system
The basics of industrial cleaning are 1) washing – 2) rinsing – 3) drying.
1) Washing: dirt on the items being cleaned is removed by the chemical solution force ofthe solvent and the physical force of ultrasonic wave, etc.
2) Rinsing: Solvent used in the washing process is removed, and any dirt which was notremoved in the previous tank is removed
3) Drying: Let the solvent used in the rinsing evaporate at a temperature in a range which
does not have an adverse effect on the items being cleaned for removal
Typical wet type open style 3-tank type cleaning system
Cooling coil

Water removal

Duct

Water
separator

Float switch

Solid removal
Pressure
meter

Cooling coil

Ultrasonicvibrator

Heater

Cooling pipe

FilterFilter pump

Soak cleaning tank

Rinsing tank

Steam cleaning tankDistillation still

Key measures for emission amount reduction in the industrial cleaning process
Types of measures

Concrete method

Cleaning process improvement

・Procedure of start-up/stop
・Reduction of airstream around the cleaning
equipment
Operation
improvement

・Examination of Dwell method
・Reduction of liquid taken out by the items
being cleaned
・Change of local emission method

Cleaning
equipment
improvement

・Installation of lids/cover・Proper cooling effect・Securing free board ratio

Introduction ofalternative
cleaning agent
Introduction or
retrieval/recycling
equipment
Airtight equipment

6・Water type, semi-aqueous type, hydrocarbon
type, halogen (fluoride, bromide), etc,
cleaning agent

VOC emission control effect(Note: confirm details)
Approx. 60 – 90%(refer to model cleaning
equipment data p.9)
Approx. 15– 80%(refer to model cleaning equipment
data p.11)
Approx. 80%(refer to model cleaning
equipment data p.12)
Approx. 70 – 85% (refer to model
cleaning equipment data p.10)
Approx. 80%(refer to model cleaning
equipment data p.13)
Approx. 10 – 30% (refer to model
cleaning equipment data p.14)
Approx. 20%(refer to model cleaning
equipment data p.15)
100%(emission of alternative substance
not included)

Initial cost required forthe measures
Zero
From about ¥100,000
Zero
About ¥10,000
0 - ¥1milion¥10,000 – 500,000¥100,000 – 1million
Less than ¥1million
Several tens of million
yen (replacing
equipment)

・Activated carbon adsorption method
・Cryogenic condensation method

60 – 80%

Several million 20million yen

・Depressurized steam cleaning system
・Airtight cleaning equipment

70 - 80%

Several million –20million yen

Summary of VOC emission control technology

Checking factors of VOC generation
Process flow and check point chart
Process
flow

Check point

Preparation

Cleaning/drying

Storage· Is there no over-washing?
· Is the start-up/stop procedure of cooling equipment andheater correct?
· Is the cooling water flowing? Is the temperatureappropriate?
· Are the items being cleaned placed correctly?
· Is cleaning agent leaking when filled/replaced?
· Is there airstream around the cleaning equipment?
· Is the local emission aspirated too highly?
· Can the local emission form be changed?
· Is the free board ratio correct?
· Are the items being cleaned put in/taken out slowly?
· After washing, is the moisture removed? Are they allowed
to dry in the upper layer of the vapor zone?
· Is there a lid or a cover on the cleaning tank?
· When the lid is put on, is the lid below the local emission
aspiration vent?
· Can alternative cleaning agent be used?
· Can VOC processing equipment be fitted at the emission
opening?
· Is the temperature controlled in the storage area?
· Are the cans shielded from direct sunlight?
· Are the lids of solvent always closed tightly when not inuse?

Factors of
VOC emission
in the air

Aim of VOC
generation
rate

Volatilization ofcleaning agent
when pouredin

About 30%

Volatilization ofcleaning agent

About 70%

Volatilization ofcleaning agent
in storage

Less thanabout 5%

Flowchart of VOC emission control
Considering
non-cleaning

Improving cleaning
process (reviewing start
up/stop procedure)Considering introductionof alternative cleaning
agent

Improvement of cleaning process
Reduction of airstream around the cleaning
equipment
Change of local emission method
Examination of Dwell method
Reduction of liquid taken out with the items being
cleanedInstallation of lids/covers
Proper cooling effect
Securing free board ratio
Considering introduction of
retrieval/recycling equipment

Considering airtightcleaning equipment

7

Improvement of cleaning
process
Procedure of start-up/stop◎Important point◎
Emission loss can be reduced by proper start up/stop procedure of water cooling equipment(chiller) and heater.

◎Comments◎
If the temperature of the cleaning agent is raised while the temperature at the cooling zoneof the cleaning tank is not fully lowered, VOC emission in the air will increase. Follow theprocedure described below to start up/stop the cleaning system.
Let it rest a while after start up until the temperature/flow of cooling water becomesstable (about 10 minutes) before turning on the heater switch. Also check if the work is done
properly following this procedure with a work check list, etc.

Procedure of start up/stop of cleaning system

Start
up

1) Cooling water ON (wait for a while, about 10 minutes)↓2) Open the lid slowly↓3) Heater, etc, ON↓4) Confirm that it is in stable condition (set temperature)↓5) Start cleaning operation

Stop1) Heater, etc, OFF↓2) Close the lid↓3) Confirm that the temperature in the cleaning tank is lowered toroom temperature↓4) Cooling water OFF (constant flow is preferred)(Made based on “Handbook for a proper use of chlorocarbon” 2000,
Japan Association for Hygiene of Chlorinated Solvents)

8

Improvement of cleaning process

Reduction of airstream around the cleaning equipment◎Important point◎
To reduce airstream generation around the cleaning equipment
When airstream blows onto the cleaning equipment from outside, diffusion of cleaning agent
vapor is promoted, becoming a huge factor affecting VOC emission increase.

VOC emission
control effect▲60 – 90% (Reduce the airstream in the environment to 0.25m/s – 0m/s from 1.25m/s.

Initial costfrom about ¥100,000 (detail: installation of screen board, covering withsheet, etc.)

Running coltnone

Installation of screen board, covering with sheet)◎Comments◎
In the normal type of cleaning equipment with the opening on the top, it is inevitable for thecleaning agent vapor generated in the cleaning tank to diffuse from the opening. If an
airstream is blowing where cleaning equipment is situated, diffused vapor is blown away
quickly, promoting more diffusion, resulting in a greater VOC emission level. If there is adoor or window near the cleaning equipment, and outside air is blown in at the
opening/closing, this phenomenon happens. According to a report, compared with theno-airstream condition, approx. 0.3 – 0.5m/s of airstream (faintly perceptible airstream
velocity) multiplies emission by 2 to 3 times, and 1m/s airstream multiplies it by 10 times.
VOC emission amount due to this factor has a larger impact than emission by other factors,
therefore it needs to be dealt with.
Examples of airstream around the cleaning equipment are1) open window in theworkroom to alleviate odor or heat, 2) cleaning equipment is placed near a door facing
outside, 3) operation of a local cooling device or fan toward the workers to alleviate heat in
the summer, etc.
It is preferable if these issues can be solved, however, at the very least it is necessary toproperly install screens to effectively protect against airstream.
Actual equipment data of quantitative measurement
experiment indicating VOC emission control effect[Experiment condition]

Airstream velocity aroundthe cleaning equipment
Free board ratio
Cooling water amount
Local emission velocity

VOC emission rate (kg/h) (in operation)

When the airstream around theequipment is reduced from1.65m/s to 0.25m/s, approx.
¥27,000 cost reduction

When the airstream around theequipment is reduced from1.65m/s to 0m/s, approx. ¥44,000
per month cost reduction (VOC
emission amount in the air isreduced by about 90%)

Airstream around the cleaning equipment (m/s)(Airstream velocity around the cleaning equipment is measured right in front of the equipment [place where operator stands is assumed])

9

Improvement of cleaning process

Change in local emission method◎Important point◎
To review the local emission equipment to optimize the volume of airstream
VOC emission can be controlled by optimizing the airstream volume of local emission. Also
the form of local emission equipment alters the wind flow around the cleaning tank.
Changing the form of the hood, etc, can control VOC emission.
VOC emission
control effect▲70-85% (airstream volume in the closed type local emission is reduced from 0.8m/s to 0.4 –Initial cost

0-¥1million (detail: change of local emission equipment costs around¥1million)

Running colt

none

0.6m/s)◎Comments◎
There are two types of local emission equipment; the side attachment type and the closed
type. In cleaning equipment, the latter has much less VOC emission than the former since
there is no airflow blowing into the cleaning equipment. Therefore it is preferable to set up aslit type sucking gate all around the opening of the cleaning equipment to control the level ofsucking velocity at around 0.4m/s.
* Supplementation (Regulation of legally controlled airstream velocity in the Labor Safety
and Sanitation Law)
According to the regulation dealing with organic solvent poisoning prevention in the Labor
Safety and Sanitation Law, it is mandatory to install local emission equipment for work
environment safety when chloride cleaning agent is used. The legally controlled airstream
velocity is regulated at the sucking gate (For the hood in the closed type, a controlled
velocity of no less than 0.4m/s).
Actual equipment data of quantitative measurement
experiment indicating VOC emission control effect[Experiment condition]
Local emission airstream
velocity
Free board ratio
Cooling water temperature

Sucking duct for local emission

VOC emission rate (kg/h) (in operation)

Cooling water flow rate

When the local emission airstream
velocity is reduced from 0.8m/s to
0.4m/s, approx. ¥22,000 per monthcost cutting (VOC emission amountin the air is reduced by about 85%)

Local emission airstream volume (m/s)

10Improvement of cleaning process

Examination of Dwell method (let the items being cleaned dry
above the vapor zone)◎Important point◎
To conduct Dwell (let the items being cleaned dry above the vapor zone)
After steam cleaning, temporarily store the items being cleaned above the vapor zone aslong as possible to allow the attached solvent to evaporate well. After it is condensed andretrieved by the cooling coil, take out the items being cleaned.
VOC emission
control effect▲15 – 80%

Initial cost

none

Running colt

none

(from no Dwell to 30 seconds Dwell)◎Comments◎
Place the items being cleaned so that the bottom of them will come to about 5cm above theborderline of vapor zone generated by cooling. Also, it is preferable if most of the items are
surrounded by the cooling coil.
Allow the cleaning agent which is wetting the items to evaporate by Dwell. About half of it iscondensed and retrieved by the cooling coil. If the items are placed higher than the upper
end of the cooling coil, attached cleaning agent cannot be retrieved. Most of it will be emitted
as VOC.
Good results can be obtained when proper placement is done and do Dwell for about 30
seconds while considering the through put (work time).
Actual equipment data of quantitative measurement
experiment indicating VOC emission control effect[Experimentcondition]

none

Dwell time

0.5min1min

Iron (board, without devising)

Steel (plate, with devising)
Steel (mass)

Amount of cleaning agent to be taken out (g/Dwell)

Batch amount (takt/day)Steel (plate:
without devising)
Steel (plate: withdevising)
Steel (mass)

30 seconds of Dwell iseffective in reducing theamountofcleaning
agent to be taken out.
Dwell is effective in mass
form also.

For steel (plate): without devising)
0.5 min Dwell is approx. ¥2,500
cost cutting (VOC emission in the
air is reduced by about 15%)

For steel (plate): with devising)
0.5 min Dwell is approx. ¥14,000
cost cutting (VOC emission in the
air is reduced by about 80%)

For steel (mass) 0.5 min Dwell isapprox. ¥1,800 cost cutting (VOC
emission in the air is reduced byabout 80%)

Dwell (drip dry) time (min.)11

Improvement of cleaning process

Reduction in amount of liquid taken out by items being cleaned◎Important point◎
To reduce the amount of cleaning agent taken out by the items being cleaned as much as
possible.
When they are taken out of the cleaning tank, arrange them in the basket in such a way thatthe liquid is not pooled, or that they are not piled up.
VOC emission
control effect▲80%(from laying plate-like items horizontally to vertically) *Not applicable for mass form

Initial cost

about ¥10,000 (detail: modifying baskets)

Running colt

none◎Comments◎
After soak cleaning, vapor cleaning is done. When the temperature of the items being
cleaned rises due to the heat of vapor until it is the same as that of vapor heat, no morecondensation is generated, finishing vapor cleaning. After that, the items are taken out fromthe vapor zone. Depending on the form of the items (dented which makes solvent form pools,
hollow, layered parts, etc,) or the arrangement in the basket, cleaning agent, besides wetting
the surface of items, can become pooled at piled-up parts, etc. without flowing down.
Taken out of the equipment this condition, extra VOC emission is generated for the amountof taken out liquid. Therefore consider ways so that there is minimum liquid pooling in theitems when they are taken out of the cleaning tank, or arrange them in the basket without
piling them up.
Actual equipment data of quantitative measurement
experiment indicating VOC emission control effect[Experimentcondition]

Dwell time

1min

Steel(plate, without devising)

Steel (plate, with devising)Amount of cleaning agent to be taken out (g/Dwell)

Steel (mass)

Iron (board: without devising)Compared with no devising case,about ¥10,000/month cost cutting(VOE emission in the air isreduced by about 80%)
(Converted as 120 tak /day)Steel (plate: with devising)

Steel

Steel

(28 sheets of plate: without (28 sheets of plate:devising)with devising)Steel(2 pieces of mass)

Steel (mass)

12

Improvement of cleaning process

Installation of lids/cover◎Important point◎
When there is airstream around the equipment, installation of lids/cover on the cleaning tankcan prevent cleaning agent vapor diffusion from the cleaning tank, reducing VOC emission..

VOC emission
control effect▲ 80%

Initial cost

¥10,000 - ¥500,000 (detail: building airtight lid, automatic open/close
lid costs about ¥500,000)

Running colt

none

(Tight-fitting lid is used below the sucking gate)

Some offices reduced cleaning agent (methylene chloride) by 27%, another cleaning
agent (trichloroethylene) by 14% by encouraging lid installation. (Federation of Electro
Plating Industry Association, Japan, Voluntary measures data)◎Comments◎
To install a lid/cover with a high degree of tightness to prevent vapor diffusion when thecleaning equipment is not in use. Lids are highly effective especially when cooling water is
stopped with the equipment not in use, such as at night. For equipment installed with closed
type local emission equipment, the lid should be under the sucking gate to be effective.
Also in automatic conveyer type cleaning equipment, modification by installation of a sliding
type automatic shutter which opens the lid when the items being cleaned go into/out of thecleaning tank can achieve effective VOC emission control.
Actual equipment data of quantitative measurement
experiment indicating Voc emission control effect[Experimentcondition]

WithoutlidWith lid

Without lid/without airstream

Free board ratio
Cooling water temperature (℃)

Cooling water flow rate (L/min)
Local emission airstream velocity (m/s)
Airstream around the equipment (m/s)
Emission rate during operation (kg/h)

If an unnecessary lid isinstalled in a
no-airstream condition,
the emission loss on
opening/closing the lid
has a large impact.

VOC emission rate (kg/h) (in operation)

When the lid is newly installed,about ¥150,000 per month cost
cutting (VOC emission in the air
is reduced by about 80%)

Lid on top of the cleaning equipment

Without lid

With lid

Without airstream

13

Improvement of cleaning process

Proper cooling effect◎Important point◎

To lower temperature of cooling coil cooling water on the upper part of the cleaning tank, orto adjust to proper cooling water flow rate.
By lowering the temperature of cooling coil cooling water, diffusion of cleaning agent vapor
is controlled, which results in reduction of VOC emission.
VOC emission
control effect▲10-35% (Change cooling water temperature from 25℃to 15℃, 10℃)

Initial cost¥100,000 - ¥1 million (detail: attaching and augmenting water cooling

Increased running colt

about twice as much (detail: electricity consumption by the water coolingequipment (chiller), water cost, etc.)

An office reduced the cleaning agent (trichloroethylene) usage by 47% by the
improvement of water cooling equipment (chiller). (Federation of Electro Plating
Industry Association, Japan, Voluntary measures data)

equipment (chiller))◎Comments◎
Methylene chloride has a lower boiling point (40°C) compared with trichloroethylene.
Therefore the diffused amount of cleaning agent vapor increases when the watertemperature in the cooling coil is high. For this reason, the cooling water temperature should
be set at 5-15°C when using methylene chloride. If low temperature cooling water cannot be
supplied from other equipment, etc, an exclusive cooling water equipment (chiller) should be
attached.
When using trichloroethylene (boiling point 87°C) or tetrachloroethylene (boiling point
121°C), the cooling water temperature at the entrance should basically be set to under
25°C.
When humidity is high, such as in the rainy season, use of excessively cold cooling water(under 10°C), means moisture in the room tends to condense, causing water to enter thecleaning liquid. Attention should be paid not to lower the temperature too much.
Actual equipment data of quantitative measurement
experiment indicating VOC emission control effect[Experiment condition]
VOC emission rate (kg/h) (in operation)

Remarks

When the cooling watertemperature is lowered from
24°C to 9.7°C, about¥1,400/month cost cutting.
(VOC emission in the air isreduced by about 35%)

Cooling water temperature (°C)

14

Cooling watertemperature
Free board ratio
Cooling water flow rate
Local emission airstream
velocity

In a quantitative measurement
experiment, it was observed thata vapor line was not formed and
VOC emission by the cleaning
agent increased drastically when
the cooling water flow rate wasdecreased to 10L/min. At thesame time, no significant change
was observed over 25L/min.
Therefore it is important tomaintain the cooling water flowrate over a certain volume.

Improvement of cleaning process

Securing free board ratio◎Important point◎
Free board ratio secures a proper size. When the free board ratio is small, the cooling agent
vapor in the cleaning tank is not cooled enough, so un-condensed vapor diffuses from thecleaning tank, resulting in increased VOC emission. By enlarging the free board ratio, loss ofcleaning agent by diffusion can be minimized.
VOC emission
control effect▲20% (when free board ratio is secured from 1.1 to more than 1.4)

Initial costless than ¥1 million (detail: augmenting walls of the cleaning tank andcooling coil, installation of steps for work, etc.)

Running colt

none◎Comments◎
The distance between the surface of vapor condensation and the top of the cooling coils iscalled free board. When the steam cleaning tank is in idling condition (not in cleaning
process) and when there is no airstream on the cleaning tank, the height of free board has alarge effect on the diffusion of cleaning agent vapor.
Even with the same free board height, the difference in the size of opening of the tank of theactual cleaning equipment makes a difference in the solvent loss. Therefore the height offree board is standardized by dividing it by the shorter width of the tank, i.e. free board ratio.
The minimum standard free board ratio is not less than 0.7 for trichloroethylene with a highboiling point, not less than 1.0 for methylene chloride with a low boiling point. Modification ofequipment is necessary to secure at least the minimum standard free board ratio.
Actual equipment data of quantitative measurement
experiment indicating VOC emission control effect[Experiment condition]

Free board ratio
Cooling water temperature

Cooling water flow rate

VOC emission rate (kg/h) (in operation)

Local emission airstream
velocity<Free board ratio>

Vapor Line

Cooling coils

Free board

When free board ratio isincreased from 1.13 to 1.43,
about ¥1,000/month cost
cutting (VOC emission in the
air is reduced by about 20%)

Liquid zone

Free board ratio = b/aFree board ratio

free board ratio: ratio of distance
between the solvent liquid surface andthe top end of the cleaning tank (b) tothe shorter length of the opening of thecleaning tank (a)15Introduction of alternative
cleaning agent
Hydrocarbon type cleaning system◎Important point◎
Hydrocarbon type cleaning agent with a high boiling point generates relatively low VOC
emission when the cleaning is conducted at room temperature.
By the way, hydrocarbon type cleaning agent is classified as one of the VOCs. VOCemission is controlled by installation of depressurized drying equipment and distilling
retrieval equipment. Hydrocarbon cleaning agent is a highly flammable substance, therefore
explosion preventive measures are required. VOC emission control in this system varies
according to the drying system.
VOC emission
control effectInitial cost
Increased running colt

▲60 – 99% (attaching depressurized distilling recycling equipment achieves over 95%)

¥8million to ¥14million (detail: soak cleaning, drying system, distilling
recycling equipment, explosion preventive measures)¥40,000 - ¥80,000 (detail: electricity, maintenance of the equipment)◎Comments◎
Various drying systems in the hydrocarbon type cleaning system make a difference to thedegree of VOC emission.
1) heated airstream drying
Cleaning agent is evaporated dry by a heated airstream. Emission concentration is low,making retrieval difficult. Therefore all cleaning agent taken out to the drying process by
the items being cleaned is emitted to the air, which results in large VOC emission.
2) sucked dry
In the drying process, lots of air goes through to dry the cleaning agent. Cleaning agent
taken out to the drying process by the items being cleaned is retrieved in the retrieval
mechanism. However, the sucked drying process is not completely airtight, so cleaning
agent is emitted to the air from a large wind sucking system with a retrieval mechanism.
There is VOC emission.
3) Vacuum steam heating + vacuum drying
Steam cleaning and drying is done in a sealed vacuum space. (Thermal energy is given
to the items being cleaned by vacuum steam cleaning)
When the vacuum degree is increased, attached cleaning agent evaporates and dries
rapidly. There are two types of retrieval mechanism; physically adsorbing and retrieving,
and cooling and retrieving in liquefied form. Since the vacuum drying process is done in acompletely airtight space, most of the cleaning agent taken out by the items being
cleaned is retrieved by the retrieval mechanism, resulting in low VOC emission.
(Example) Grease removal cleaning of machine processing
part
Rough cleaning
General cleaning
Precise cleaning
Soak and shaking,Soak ultrasonic,
Soak ultrasonic x 2
soak and shaking
showerHeated airstream
Heated airstream
Depressurized
dryingdryingvapor
Distilling recycling,
Distilling recycling, Distilling recycling,augmented
augmented
augmented
security/explosion
security/explosion
security/explosion
prevention, foam
prevention, foam
prevention, foam
fire extinguisher
fire extinguisher
fire extinguisher
Initial cost:
Initial cost:
Initial cost:¥8.3 million¥11.8 million¥13.5 million
Running cost
Running cost
Running cost
¥35,000¥81,000¥60,000
Electricity ¥27,000 Electricity ¥67,000 Electricity ¥43,000
Maintenance
Maintenance
Maintenance¥8,000¥14,000¥17,000
Industrial waste ¥0 Industrial waste ¥0 Industrial waste ¥016Structure of hydrocarbon type cleaning system

Hydrocarb
on type(3-tankstructure)

CleaningtankDistillation
still

Rinsingtank

DryingsystemP:pumpF:filterHeatedairstream
generator, etc.

*Supplementation
Among the hydrocarbon type cleaning systems, “depressurized steam cleaning+ vacuum drying” system conducts all the procedure(cleaning, rinsing anddrying) in an airtight container. Therefore most of consumed cleaning agent
comes from waste liquid (hydrocarbon type cleaning agent + processing oil,etc.) discharged from the attached depressurized distilling recycling equipment.
In this system, emission to the air is very little from the vacuum pump.
This will be described in the “depressurized steam cleaning system” in airtightcleaning equipment section.

Introduction of alternative cleaning agent

Semi-aqueous type cleaning system◎Important point◎
Semi-aqueous type cleaning agent can be rinsed with water. It has a strong cleaning force against organic
dirt, at the same time ionic dirt can be removed by rinsing with water. Semi-aqueous type cleaning agent
mainly consists of glycol-ether mixture (surfactant, water). It also includes N-methylpirrolidone type, terpene
type, and alcohol type. VOC emission is close to zero apart from the N-methylpirrolidone type and alcohol
type.
Standard semi-aqueous cleaning system is 4-tank type (washing – pre-rinsing – finish rinsing – drying).
Since it uses water for rinsing, drying is required. Generally pure water recycling equipment is attached.
VOC emission
control effectInitial cost
Increased running colt

▲95 – 100%

(100% when glycol-ether type cleaning agent is used and rinsed with water)¥6 million - ¥13million (detail: 4-tank type cleaning equipment (withdryer), pure water recycling equipment)¥50,000 - ¥140,000 (detail: activated carbon replacement, industrial
waste, electricity, equipment maintenance)◎Comments◎
VOC emission from the semi-aqueous type cleaning system varies according to the type of cleaning agent and rinsing
agent.
1) Glycol-ether type cleaning agent hardly evaporates at all, therefore VOC emission is zero as long as it is rinsed
with water.
2) When the alcohol type is used for rinsing, alcohol taken into the drying tank at drying is emitted as VOC.
3) Inflammable cleaning agent evaporates when it is heated in the cleaning process, and is emitted as VOC, but it
can be kept to a minimum by the use of retrieval equipment and airtight procedure. If the water content is replacedwith alcohol for drying, the alcohol taken out becomes VOC emission. Efficient drying equipment should be used
and water should be used for rinsing if possible.
Standard use of semi-aqueous type cleaning agent
1) Washing procedure (ultrasonic, shower, JET in the liquid, etc.) cleaning temperature (60 - 70°C)
2) Pre-rinsing (tap water or pure water, room temperature - 40°C) – replacing liquid once to twice a month3) Finish-rinsing (pure water at room temperature - 50°C) Discharged water can be sealed watertight by recycling
using pure water recycling equipment (activated carbon, ion exchange resin)4) Drying (heated airstream 70°C - 90°C)
Types of semi-aqueous cleaning agent
1) non-flammable (non-hazardous substance)
1) glycol – ether mixture (surfactant, water)2) hydrocarbon + glycol –ether mixture(surfactant, water)
3) N-methylpyrrolidone (NMP) mixture(surfactant, water)2) flammable (hazardous substances)
4) terpene type solvent mixture (surfactant)5) N-methylpyrrolidone mixture (surfactant)6) glycol – ether mixture (surfactant)7) alcohol type cleaning agent (IPA, denatured
alcohol)(Example) Printed circuit board /electronic parts (flux removal) cleaning
Rough cleaning
General cleaning
Precise cleaning(3-tank type)(4-tank type)(4-tank type)
Ultrasonic 2 sets, jet
Soak ultrasonic 1 set
Ultrasonic 3 setsflow
Pure water rinsing x
Pure water rinsing x
2, pure water
Tap water rinsing
2, pure waterequipment, rinsing
recycling equipment
purificationequipment
Heated airstream
Heated airstream
Heated airstream
dryingdryingdrying
Initial cost
Initial cost
Initial costequipment:
equipment: ¥10
equipment:¥6 million
million¥130million
Running cost total:
Running cost
total: Running cost total:¥91,000¥144,000¥177,000
Cleaning agent 30kg Cleaning agent 30kg
Cleaning agent 30kg
¥36,000¥36,000¥36,000
Industrial waste
Industrial waste
Industrial waste
234kg
234kg
334kg
¥14,000¥14,000¥20,000
Recycling cost
Recycling cost
Recycling cost¥0¥45,000¥55,000
Electricity¥27,000
Electricity¥33,000
Electricity ¥48,000
Maintenance cost
Maintenance
cost
Maintenancecost¥8,000¥16,000¥24,000

Structure of semi-aqueous type cleaning system

Semi-aqueous type(4, 5-tankstructure)

Cleaning
tank

Returningoriginal liquid

Rinsingtank

Waterrinsingtank

Waterrinsingtank

Pure water
recyclingequipment.

Oil/water
separation

P:pumpF:filter*RC: monthly running cost (total of industrial waste, electricity, maintenance,and recycling costs)
Condition for calculating running cost procedure consists of washing – pre-rinsing – finish-rinsing- drying
 cleaning equipment operates manually each cleaning tank can contain 100L
 cleaning agent is ¥1,200/kg, entire agent is replaced every 3 months
 monthly supplemented cleaning agent is 30kg, industrial waste cost ofcleaning agent and rinse 1 water is ¥60/kg
 rinse 2 is recycled by pure water recycling equipment, 25L each of activatedcarbon, ion exchange R, operation condition 10hours/day x 22/month17

Introduction of alternative cleaning agent

Water type cleaning system◎Important point◎
When water type cleaning agent (alkali cleaning agent, surfactant type cleaning agent, acid typecleaning agent, and mixture of alkali and surfactant cleaning agent) is used, there is no VOC
emission. Discharged water neutralization treatment and water purification (recycling) becomes
necessary. In this system, separate consideration for discharged water is necessary.
VOC emission
control effectInitial cost
Increased running colt

▲100%

(when all the cleaning agent is converted to water type)¥5 million to ¥20 million (detail: ultrasonic cleaning equipment, drying
equipment, pure water recycling equipment)¥50,000 - ¥230,000/month (detail: electricity, waste treatment cost,water recycling equipment cost)◎Comments◎
Water type cleaning agent does not include flammable or volatile substances, also it is safe.
At the same time, consideration for discharged water is necessary. There is a way to use
water type cleaning agent without newly installing a large scale discharged water treatment
facility.
· Rinsing water recycling system
In this system, discharged water from the rinsing process is recycled in the attachedequipment. Discharged water from the rinsing process is distilled in the distilling
equipment, and the collected distilled water is used again as rinsing water. Or in thecase of precise cleaning when ion exchanged water is required for rinsing, the distilledwater is put through ion exchange equipment to be used again.
Also there are cases to use microfiltration membrane, ultrafiltration membrane, etc.
· Oil and water separating system
Oil and water separating type cleaning agent is long lasting as well as requiring lessfrequent replacement. Also, some systems promote oil and water separation by working
on the cleaning equipment or using attached equipment. In the cleaning equipment,
reservoir tank is enlarged in the cleaning agent circulation line. This enables stabilizationof the cleaning agent to non-moving status as much as possible, which floats themixed-in oil. Also there are methods to install oil and water separating equipment as theattached equipment in the circulation line of cleaning agent to actively remove themixed-in oil (oil and water separating membrane type, pressurized floatation type, andelectrostatic separation type).
· Non-rinsing system
This is used in rough cleaning. In this cleaning equipment it is necessary to suppress
re-attachment of dirt mixed in the cleaning agent onto the items being cleaned, requiring
oil and water separation system, cleaning agent filtering system, etc. Since this cleaning
process requires only a cleaning tank and a drying tank, there is an advantage of smaller
cleaning equipment compared with general water type cleaning equipment.
(Example) Metal parts (grease removal) cleaning
Precise cleaning
Rough cleaning
General cleaning(4-tank)
Soak ultrasonic x 2 Soak ultrasonic x 3
Soak ultrasonic x 2Core lesser
Membrane separation
Heated airstream
Heated airstream
Depressurized vapor
dryingdrying
Initial cost:
Initial cost:
Initial cost :¥5.5 million¥9.5 million¥17.5 million
Running cost
Running cost:
Running cost :¥53,000¥143,000¥229,000
Electricity ¥26,600 Electricity ¥33,400 Electricity¥100,000
Maintenance cost
Maintenance cost
Maintenance cost
¥71,600¥8,000¥583,000
Industrial waste
Industrial waste
Industrial waste¥12,000¥18,000¥6,000Cylinder¥0 Cylinder ¥45,000 Cylinder ¥45,000

18Structure of water type cleaning system

Water
type

Cleaningtank
Oil andwater
separation

Cleaning agent isreturned

Water
rinsingtank

Waterrinsingtank
Aftertreatment,water isdischarged or
recycled
Discharged water
treatment
equipment

Heatedairstream
drying orcentrifugal,
vacuum drying
Discharged
water orindustrial
wasteIntroduction of
retrieval/recycling equipment
Retrieval/recycling equipment by cryogenic condensation◎Important point◎

When cleaning agent vapor concentration is high, retrieval equipment by cryogenic condensation canbe attached. In the retrieval equipment by cryogenic condensation, cleaning vapor is sucked,
condensed and cooled for retrieval. This method is good when cleaning agent vapor concentration isrelatively high and airstream is slight. It is effective for the process of retrieval very near the generatorof cleaning agent vapor.
VOC emission
control effect▲50 – 80%(depends on the condition of cleaning equipment)

Initial cost

¥8 million - ¥12.5 million (detail: retrieval equipment, duct, water
separator, installation work cost, etc.)

Increased running colt

¥10,000 - ¥100,000/month (detail: electricity, cooling water cost)◎Comments◎
Retrieval equipment by cryogenic condensation consists of compressor which can suck and pressurize,
condensing part to condense pressurized gas, and water separator to separate retrieved VOC and water.
1) Sucking process: High concentration gas is directly sucked in from near the vapor line in the cleaning tank2) Pre-condenser: The gas at about -30°C discharged from the cryogenic condenser passes through the innercylinder, exchanging heat with the sucked in vapor which passes through the outer cylinder. Part of it isliquefied and condensed.
3) Pressurizing process: Pressurized by compressor, apparent concentration becomes higher.
4) Water cooling condensing process:Part of the pressurized gas is liquefied and condensed by the coolingwater supplied from outside.
5) Cryogenic condensing process: Vapor which cannot be liquefied in the water cooling condenser is chilled to-30°C to -40°C to liquefy and condense (cryogenic condensation). Most of the vapor is liquefied here. In the
cryogenic condenser, moisture in the air becomes frozen over time. After a certain period, the vapor defrosts
itself by halting the flow.
6)-1 Activated carbon adsorption process: vapor which cannot be liquefied in the cryogenic condenser isadsorbed by the activated carbon.
6)-2 Activated carbon desorption process: Vapor adsorbed on the activated carbon is desorbed by indirect
heating and sucking desorption, i.e., thermal pressure swing method, and is returned to the entrance ofcompressor.
7) Condensed liquid tank:
Cleaning agent liquefied in the water cooling condenser and cryogenic
condenser is collected in the condensed liquid tank, and is regularly discharged by the inner pressure.
8) Water separation process: Retrieved cleaning agent discharged from the condensed liquid tank goes to awater separator where water is separated, then is returned to cleaning equipment, liquid tank, etc.
In combination with cleaning equipment, diffusion is controlled by sucking a small amount of gas from the vapor
zone in the cleaning equipment. VOC concentration near the local emission opening on the upper part of thecleaning equipment becomes extremely low by installing the sucking part of the retrieval equipment about 10cm
from the top of the vapor line, which results in in reduction of VOC emission.
Example of retrieval equipment bycryogenic condensation

Discharged air

Gas line

Pre-condenser

Gas pressure line

Liquid line
Cryogenic
condenser

Water
separator

Sucking

Compressor

Condensed
liquid tank

Cleaning machine

Water coolingcondenser

Coolingwater

19

Introduction of retrieval/recycling equipment

Actual case of retrieval/recycling equipment by cryogenic
condensation No.1
1
2
3

Industry type
Items to be cleaned
Amount of items to
be cleaned

Transportation machinery/parts manufacturing
Heat treated parts
approx. 100kg/batch
Closed type single tank automatedcleaning machine

Emission facility
4Outline of emission
facility5

VOC generating
condition

6

Aim of measures

7

Method ofmeasures

Size of liquid surface in thecleaning tank
Airstream amount of local
emission
Operating hours
Substance

approx. 1.9 x 1.5(m)approx. 40m³/min

24 hours/day, 22days/month
Methylene chloride (dichloromethane)
Flow-out of VOC volatilized in the cleaning
Generating condition
tank
Reduction of concentration in the emitted air (responding to prefectural
regulation)
Installation of retrieval/recycling equipment (cryogenic condensation type)
Emitted air

Water coolingmachineImage of VOC
sucking duct

Retrievalequipment

VOC retrieval
line
Coolingwater

Cleaning machineWork

8

Emission control
measures (flow)Tosolvent
tank

Emitted air
Cleaning tank
Work

Water
separator
Concentration in theemitted air
After the installation:
15ppm
Before the installation:
725ppm1) VOC emission is reduced and retrieved liquid is recycled by collecting VOC
and mist volatilized from the cleaning tank, which used to be discharged into
the air, by solvent retrieval equipment.
2) Concentration in the work environment is reduced under the standard.
Reduction effect

9

10

20

EffectCost for themeasures▲ 65%, ¥324,000/month cost cutting(Solvent usage before the installation: 2.5t/month
Solvent usage after the installation: 0.88t/month)

Emission concentration
before the installation

725ppmEmission concentration
after the installation

15ppm

OthersSolvent retrieved in the retrieval equipment isrecycled

Facility cost

¥11million (retrieval equipment)

Construction cost

¥2million (duct, transportation, installation, test
running and adjustment, etc.)

Others¥1million (water separator, attached equipment,materials, etc.)

Introduction of retrieval/recycling equipment

Actual case of retrieval/recycling equipment by cryogenic
condensation No.2
1
2
3

4

5
6
7

Industry type
Items to be cleaned
Amount of items to
be cleaned
Outline of emission
facility

VOC generating
condition
Aim of measures
Method ofmeasures

Metal products manufacturing
Rolled metal sheet
Emission facility
Size of opening part in thecleaning tank
Airstream amount of local
emission
Operating hours
Substance

Hoop type cleaning machine
approx. 0.8 x 1.2(m)approx. 5m³/min
10 hours/day, 25 days/month
Methylene chloride (dichloromethane)
Diffusion of VOC volatilized in the cleaningtank

Generating condition
Reduction of usage amount

Installation of retrieval/recycling equipment (cryogenic condensation type)
Emitted air

VOC gasretrieval line
Coolingwater

8

Emission control
measures (flow)Tosolvent
tank

Cleaning machine

VOC emission is reduced by collecting VOC volatilized from the cleaning tankwhich used to be discharged into the air by retrieval equipment.
Reduction effect910

EffectCost for themeasures▲ 85%, ¥340,000/month cost cutting(Solvent usage before the installation: 2.0t/month
Solvent usage after the installation: 0.3t/month)

Emission concentration
before the installation- ppm

Emission concentration
after the installation

10ppm

OthersSolvent retrieved in the retrieval equipment can berecycled

Facility cost

¥6 million (retrieval equipment)

Construction cost
Others¥1.2 million (duct, transportation, installation, test
running and adjustment, etc.)¥300,000 (water separator, materials, etc.)21Introduction of retrieval/recycling equipment

Actual case of retrieval/recycling equipment by cryogenic
condensation No.3
1
2
3

Industry type
Items to be cleaned
Amount of items to
be cleaned

Metal products manufacturing
Stainless pipes
400 kg /batch
Closed type double tank automatedcleaning machine

Emission facility
4Outline of emission
facility5

VOC generating
condition

6

Aim of measures

7

Method ofmeasures

Size of opening part in thecleaning tank
Airstream amount of local
emission
Operating hours
Substance

approx. 4.5 x 1.0(m)approx. 15m³/min

8 hours/day, 20 days/month
Trichloroethylene
Flow-out of VOC volatilized in the cleaning
Generating condition
tank
Reduction of concentration in the emitted air (voluntary measures forISO14001)
Reduction of concentration in the work environment
Installation of retrieval/recycling equipment (cryogenic condensation type)
Cleaning tankImage of VOC
sucking duct
Emitted air
Water coolingmachine8

Emission control
measures (flow)

Solvent
retrievalequipmentWork
VOC gas in
the cleaningtank retrieval
line
Concentration in
the emitted air

Emitted air

Coolingwater

After the installation:
30ppm
Before the installation:
2000ppm

To Solventtank

VOC emission is reduced by collecting VOC flown out from the cleaning tankwhich used to be discharged into the air by direct sucking of retrieval
equipment.
Reduction effect

9

10

22

EffectCost for themeasures▲ 59%, ¥100,000/month cost cutting(Solvent usage before the installation: 875kg/month
Solvent usage after the installation: 400kg/month)

Emission concentration
before the installation

2000ppm

Emission concentration
after the installation

30ppm

OthersSolvent retrieved in the retrieval equipment can berecycled

Facility cost

¥11million (retrieval equipment)

Construction cost

¥1.5 million (duct, transportation, installation, test
running and adjustment, etc.)

Others¥1million (water separator, attached equipment,materials, etc.)

Introduction of retrieval/recycling equipment

Retrieval/recycling equipment by activated carbon adsorption◎Important point◎
When there is a large diffusion of cleaning agent vapor or low concentration of cleaning
agent vapor, vapor is collected with large amount of airstream, adsorbed on the activatedcarbon for higher concentration, and then the cleaning agent is removed. Retrieval
equipment using this method is called retrieval equipment by activated carbon adsorption.
VOC emission
control effect▲About 65% (depending on the condition of cleaning equipment used)

Initial cost

¥6 million - ¥20 million (detail: retrieval equipment, duct, discharged
water treatment facility, installation construction, etc.)

Running cost

¥300,000/year (detail: electricity, replacement cost of activated carbon)◎Comments◎
Among the retrieval equipment by activated carbon adsorption, fixed-bed activated carbon
adsorption type retrieval equipment usually consists of 2 towers of activated carbon. The air
containing VOC sucked in the sucking blower is adsorbed on the activated carbon in theprocess of going through the tower of activated carbon, to discharge clean air. Meanwhileheated steam is blown in from the bottom of another activated carbon tower, pushing out the
VOC adsorbed on the activated carbon. Steam and VOC are liquefied through thecondensing duct, and are retrieved by gravity separation in the water separator. Separated
water goes through the discharged water treatment equipment and is discharged under thedischarged water standard. Water in the activated carbon tower desorbed by steam isfurther removed by the heated airstream, improving and reviving the adsorption amount.
Also, there is the separation and transportation type (exchange type) activated carbon
adsorption method where only an activated carbon adsorption tower is installed in thecleaning factory. The adsorption tower is exchanged when it is saturated, and transported tothe desorption factory for reviving (desorption).
Example of retrieval equipment system by fixed-bed activated carbon adsorption

Emitted air
Vapor
sucking line

Clean air
Activatedcarbon tower

Activatedcarbon tower
Steam

Cleaning
equipment
Water
separator

Compr
essed
air

Cooling tower

Cooling water

Steam
drain
Retrieved
solvent retrieval
opening
Retrievalequipment
Boilerblow

23

Introduction of retrieval/recycling equipment

Actual case of retrieval/recycling equipment by separation andtransportation type activated carbon adsorption
1
2
3

Industry type
Items to be cleaned
Amount of items to
be cleaned

4

Outline of emission
facility5

VOC generating
condition

6

Aim of measures

7

Method ofmeasures

Precision optical parts processing
Copy drums, etc.
Emission facility
coating removal equipment
Size
Airstream amount of local
100m³/minemission
Operating hours
24 hours/day, 20 days/month
Substance
methylene chloride (dichloromethane)
Substance temperature
22°C
Generating condition
continuous emission
Reduction of concentration in the emitted air (responding amended air pollution
control law, ISO 14001 and PRTR )Installation of retrieval/recycling equipment (separation and transportation typeactivated carbon adsorption)
Blower NO.3 1/2 – 11KW (100³/min – 300mmAq)

VOC gasAutomatic
dumperScrubber

8

Emission control
measures (flow)

Drain (replacement
once/month, treatedas industrial waste)

Emitted in
the air

Temperature sensor
for fire extinguisher
Thermometer

924

EffectReduction effect▲ 65%, ¥108 million/month cost cutting(Solvent usage before the installation: 8t/month
Solvent usage after the installation: 2.8t/month)

Emission concentration
before the installation

600ppmEmission concentration
after the installation

30ppm

Airtight cleaning equipment
Depressurized steam cleaning system◎Important point◎

In the depressurized steam cleaning system, all of the processes (washing – rinsing – drying)
are conducted in an airtight container. Therefore solvent usage is reduced to 1/2 – 1/10.
Most solvent consumption comes from waste liquid (hydrocarbon type cleaning agent,
processing oil, etc.) emitted from the attached depressurized steam recycling equipment.
Only a small amount of cleaning agent VOC emission comes from the vacuum pump.
VOC emission
control effectInitial cost
Running cost

▲50 – 90% (depending on cleaning system)from about ¥20 million (detail: exclusive cleaning equipment,
depressurized steam recycling mechanism, vacuum drying equipment,
etc.)
several tens of thousand yen (detail: vacuum pump operation cost, etc.)◎Comments◎
The depressurized steam cleaning system consists of a heating mechanism to heatcleaning agent, steam generating tank connected to the depressurizing mechanism via
condenser (retrieval equipment) to enable continuous depressurization, and cleaning tankconnected to depressurizing mechanism via condenser to enable continuous
depressurization. Those are connected via a control valve.
Basic structure of depressurized steam cleaning systemusing hydrocarbon type cleaning agent

VOC emission in the air(hydrocarbon cleaning agent)

Cleaning tank

Depressurized
steam
generating
mechanism(depressurized
steam recycling
mechanism)

Items to becleaned

Condenser(retrieval
equipment)

Depressurizing
mechanism(vacuum pump)

Emitting cleaning agent waste liquid with processing oil mixed in(processing oil + hydrocarbon type cleaning agent)

Depressurized steam cleaning system features:1) Improved safety since work is done in an airtight container
2) Compared with the heated airstream drying method, cleaning agent emission in the air is
1/17 – 1/34, which reduces environmental burden. Compared with the heated airstream
drying method, running cost is reduced, too.
3) Cleaning performance is stabilized since the depressurized steam recycling mechanism
is attached as a standard.
4) Cleaning performance is improved since the attached ultrasonic mechanism enables
cleaning by deaeration and ultrasonic wave.

25

Airtight cleaning system

Completely airtight cleaning equipment◎Important point◎
In completely airtight cleaning equipment, volatile solvent including hydrocarbon typecleaning agent can be used, involving airtight equipment and solvent recycling.
There is no water discharge, causing no environmental problem by discharged water and is
exempted from legal regulation. Operation is in dry condition in the cleaning tank, which
does not cause hydrolysis of cleaning agent, etc. Also a slight supply of nitrogen ensures
maintenance of a nonflammable atmosphere. Therefore it can be used in temperatures
above flash point.
VOC emission
control effect▲About 99%

Initial cost

¥6 million - ¥17 million (detail: when chloride type cleaning agent is used in
vacuum style completely airtight single tank automated cleaning equipment)

Running cost(cleaning agent emission is almost zero. Cleaning agent in the waste liquid only. )¥40,000 - ¥70,000 (detail: mainly electricity)◎Comments◎
All the equipment is connected and sealed completely airtight via pipes to prevent the airfrom entering the cleaning equipment system or to prevent the cleaning agent vapor fromemitting. A flexible gas holder is connected to respond to the change of gas amount in theequipment. The whole equipment is constantly kept at a minute positive pressure. There isno internal gas leak or ingress of air from outside.
Also it is devised not to let air come in or cleaning agent vapor go out of the system whenitems to be cleaned are put in and taken out. Air coming with the items being cleaned isexpelled out of the system by the vacuum pump before the items are brought into thecleaning system. Also cleaning agent vapor is retrieved into the system by the vacuum
pump before the items to be cleaned are taken out. When inflammable cleaning agent isused, space within the system where cleaning agent exists is replaced by nitrogen,maintaining oxygen concentration under the combustible point.
Concept of completely airtightcleaning equipment

Solvent emission out of the work place < 1(kg/month)(zero is achievable with relative ease)

Items to becleaned in and out
opening

Cleaning

Solvent amount = oil amount x aequipment(a can vary according to the equipment,
zero is achievable)

No emission
Solvent emission into the place: 0.0g/h(exempted from application of organic solvent
poisoning preventive regulation)* Cleaning tank capacity = 55 L (420 x 300 x 430mm)* Tact time = 3 minutes* Cleaning agent = methylene chloride

26

Reference

Air pollution

Labor Safety and Sanitation

Environmental risk measuresfor chemical substances

Emission standard (at outlet)(Air Pollution Control Law)

Division of organic solvent(Ordinance on Prevention ofOrganic Solvent Poisoning)

Act on Confirmation, etc. of Release Amounts ofSpecific Chemical Substances in theEnvironmental Quality Standard
Concerning Air Pollution (Basic
Environment Law)

Controlled concentration(in the work place)(Labor Safety and Sanitation Law)
Work Environment Evaluation
Standard(Controlled
Concentration)· methylene chloride
50ppm· trichloroethylene
25ppm· tetrachloroethylene
50ppm

Applicable Volatile Organic Compounds (VOC)· methylene chloride· trichloroethylene· tetrachloroethylene
Designated substance emitting facilities anddesignated substance control standard
cleaning facilities (over 3m²is exposed to theair)

PRTR Law

Environment and Promotion of Improvements to
the Management ThereofClass 1 designatedsubstances· methylene chloride· trichloroethylene· tetrachloroethylene

chemicalIndustrial Waste· trichloroethylene existing 500mg/m² new 300mg/²· tetrachloroethylene existing 500mg/m² new 300mg/²

Special Management Industrial Waste(Waste Disposal and Public Cleansing
Law)
Class 1 designatedsubstances· methylene chloride· trichloroethylene· tetrachloroethylene

Emission Outlet

chemical
50ppm
25ppm
50ppm

Special Management Industrial Waste(Waste Disposal and Public Cleansing
Law)

Cleaning
equipment
Drainage way

Soil pollution

Underground water pollution

Order of Soil Pollution Removal
Measures(Soil Contamination
Countermeasures Law)

Underground permeationprohibiting
Effluent standard (acceptable
limit)
Order of Measures concerning
Underground Water Purification(Water Pollution Control Law)
Environmental quality standard
concerning Water Pollution(Basic Environment Law)

Environmental quality standard

concerning Soil Pollution(Basic Environment Law)
Designated area··

methylene chloride no more than 0.02mg/1l tested liquid·

tetrachloroethylene no more than 0.01mg/1l tested liquid

trichloroethylene no more than 0.03mg/1l tested liquid

Effluent standard (acceptable limit)··

methylene chloride
trichloroethylene

no more than 0.2mg/l
no more than 0.3mg/l·

tetrachloroethylene

no more than 0.1mg/l

Key regulations applied on chloride solvents

27

Appendix:Actual quantitative measurement experiment raw data
Experiment on actual machine on airstream
velocity around cleaning equipment(Site photo)Appearance of thecleaning equipment
installation site
including a window

In normal operation

Cooling down

Duringthe night

Loss inone day

Change of weight of the cleaning agent
within the cleaning equipment

Warming up(Experiment condition)
Velocity around the cleaning
equipment (m/s)

Change oftotal weightof liquid
within theequipment

Warming up (kg)
In normal operation (kg)
Cooling down (kg)During the night (kg)
Loss in one day (kg)Wind around the cleaning equipment(m/s)
Mainly the loss during the normal
operation is analyzed

Experiment on actual machineon proper cooling effect(Site photo)Appearance of chiller(cooling equipment)(Experiment condition)

In normal operation

Cooling down

Duringthe night

Loss inone day

Change of weight of the cleaning agent
within the cleaning equipment

Warming up

Cooling water temperature (°C)

Change oftotal weightof liquid
within theequipment

Warming up (kg)
In normal operation (kg)
Cooling down (kg)During the night (kg)
Loss in one day (kg)

Cooling water temperature (°C)
Mainly, the loss during normal
operation is analyzed

Experiment on actual machineon securing free board ratio(Site photo)

Increasing volume
of cooling coil inorder to raise freeboard ratio(Experiment condition)
Change oftotal weightof liquid
within theequipment

28

Free board ratio
Warming up (kg)
In normal operation (kg)
Cooling down (kg)During the night (kg)
Loss in one day (kg)

In normal operation

Cooling down

Duringthe night

Change of weight of the cleaning agent
within the cleaning equipment

Warming up

Free board ratio
Mainly, the loss during thenormal operation is analyzed

Loss inone dayAppendix:Actual quantitative measurement experiment chart, committee
members register

Quantitative measurement cleaning equipment for experiment on emission control effectLiquid surface measurement part of vapor tankCommittee for Creating and Examining Voluntary Measures Manual at Industrial Cleaning for VOC
Emission Control by Cutting Down Cost and Work Environment Improvement Activities
Members Register

Name
Chairman
WG Chairman
Committee
memberCommittee
memberCommittee
memberCommittee
memberCommittee
memberCommittee
memberCommittee
memberCommittee
memberCommittee
memberCommittee
memberCommittee
memberCommittee
memberCommittee
memberCollaborator
ObserverObserverAffiliation

Remarks

Japan Industrial Conference on Cleaning

Cleaning equipment expert*

SPC Electronics Corporation

Cleaning equipment manufacturer*

Just Co., Ltd

Cleaning agent manufacturer *Cleaning equipment peripheral
equipment manufacturer

Taisei-Chemical Co., Ltd.

Cleaning agent manufacturer

Federation of Electro Plating Industry Association

Cleaning user organization

Asahi Glass Co., Ltd.

Cleaning agent manufacturer*

Daiwa Chemical Industries Co., Ltd.

Retrieval equipment manufacturer*

Nissin Seiki Inc.

Cleaning equipment manufacturer*

The University of Tokyo, Graduate School of Engineering,
Department of Chemical System Engineering

Professor (academics)*

Tokyo Institute of Technology, Graduate School ofEngineering, Department of Chemical Engineering

Associate Professor (academics)*

The Japan Electrical Manufacturers’ Association

Cleaning user organization

Morikawa Co., Ltd.

Retrieval equipment manufacturer

Japan Metal Heat Treatment Association

Cleaning agent user organization

Japan Association for Hygiene of Chlorinated Solvents

Cleaning agent user organization

Tokuyama Corporation

The University of Tokyo, Graduate School of Engineering,
Department of Chemical System Engineering
Ministry of the Environment, Environmental Management
Bureau, Air Environment Division, Assistant Manager
Ministry of the Environment, Environmental Management
Bureau, Air Environment Division, Chief*

Researcher (doctorate)

OfficeJapan Industrial Conference on Cleaning

Industrial Cleaning Business Organization

OfficeJapan Industrial Conference on Cleaning

Industrial Cleaning Business Organization

OfficeJapan Industrial Conference on Cleaning

Industrial Cleaning Business Organization

OfficeAsahi Research Center Co., Ltd.

OfficeJapan Industrial Conference on
Cleaning Member
Japan Industrial Conference on
Asahi Research Center Co., Ltd.
Cleaning Member(No titles, members in alphabetical order, * also serves as WG(experiment on actual machine working group) committee member)29

Publisher

Ministry of the Environment
Japan Industrial Conference on Cleaning
Asahi Research Center Co., Ltd.
(Inquiries regarding this manual)
Japan Industrial Conference on Cleaning(Denkosha Bldg. 5F) 2-10-4 Shiba, Minato Ward
Tokyo 105-0014
TEL 03-3453-8165 FAX 03-3453-8167 URL:http://www.jicc.org

March 2007