Degreasing with TCE 

in Commercial Facilities:

Protecting Workers

Background Document
Prepared by Eastern Research Group, Inc. (ERG)

This preliminary document is being presented at the TCE Expert Public Workshop. Our goals for the workshop are to: 

• Identify and understand the criteria that alternatives (chemical and/or no chemical) will need to satisfy to be 

an effective replacement.

• Understand lessons learned from previous work that can be used to inform future substitutions.

• Identify a list of measures, for example, for worker protection, other than chemical substitution, that could be 

used to reduce exposure to TCE in the given applications.

Our goals for presenting this preliminary document are to provide a starting point for discussions of worker 

protection and risk management for these uses of TCE. This preliminary document presents current examples of 

best practices; we are interested in your thoughts and feedback on the information in this document, the way it is 

presented, whether it meets our goals, and how it can be more effective at reducing exposure to TCE. 
Background Document | 1

The Issue & How to Use This Document

What is TCE?

TRICHLOROETHYLENE (also known as TCE or by its proper chemical name, 1,1,2-trichloroethene) is a 

chemical that is commonly used as a solvent. As a liquid, TCE is highly volatile, meaning that it quickly 

produces vapors. TCE has a pleasant, sweet smell, though you can breathe it in without smelling it. TCE 

vapors can also be absorbed through your skin.

Single (acute) or short-term exposure to high concentrations of TCE vapors can irritate the respiratory 

system and skin and induce central nervous system effects such as light-headedness, drowsiness, 

and headaches. Changes in heart beat have 

also been reported following TCE exposure. In 

extreme circumstances, overexposure can lead to 

unconsciousness and even death (ATSDR, 1997).

Repeated (chronic) or prolonged exposure to TCE 

has been associated with effects in the liver, kidneys, 

immune system, central nervous system, reproductive 

system and developmental effects in the developing 

fetus. TCE is carcinogenic to humans by all routes 

of exposure. TCE that enters your body can be 

transferred to your fetus if you are pregnant or to your 

child while you are nursing (EPA, 2011). 

How to Use This Document

Degreasing is the process of using solvents to remove grease, fats, oils, waxes, or soils from surfaces. The 

surfaces being cleaned typically are made of metal, but can also be glass or plastic.

EPA prepared this document to help commercial facilities that perform degreasing as part of their operations 

to reduce their health risks to TCE. You may find this document helpful if you perform degreasing with TCE in 

any of the following commercial settings:

• Repair shops—shops that repair automobiles, motorcycles, bicycles, or electronics.

• Fabrication shops—shops that fabricate metal, glass, or plastic components into a final product. 

These include a wide range of large and small facilities that produce automobiles, aircraft, 

appliances, motor vehicle parts, machine parts, and jewelry.

• Metal plating shops—shops that plate, or coat, metal onto a surface.

• Electronics assembly shops—shops that assemble a wide variety of electronic devices onto circuit 

boards, such as electric capacitors, semiconductors, and electronic instrumentation.

Degreasing is performed in a wide variety of facilities, both large and small. The methods used to degrease 

parts depend heavily on a facility’s exact function. If you do not see your exact facility type here, you may 

still be able to use this document. If you know the type of degreasing you perform in your shop, you can refer 

to the sections that discuss that type of degreasing.

Table 1 identifies the type of degreasing typically performed in each of the commercial settings discussed in 

this document.

+ –
Background Document | 2

The Issue & How to Use This Document

Outline

Personal Protective Equipment When Using TCE..........................................................................................3

Skin Protection......................................................................................................................................................................... 3

Eye Protection.......................................................................................................................................................................... 3

Respiratory Protection..........................................................................................................................................................4

Repair Shops ..................................................................................................................................................................5

Technologies That Eliminate or Reduce Risks from TCE........................................................................................6

Protecting Workers from TCE............................................................................................................................................8

Workplace Practices............................................................................................................................................................ 10

Fabrication Shops....................................................................................................................................................... 12

Technologies That Eliminate or Reduce Risks from TCE.......................................................................................13

Protecting Workers from TCE...........................................................................................................................................15

Workplace Practices.............................................................................................................................................................17

Metal Plating Shops...................................................................................................................................................18

Technologies That Eliminate or Reduce Risks from TCE.......................................................................................19

Protecting Workers from TCE...........................................................................................................................................21

Workplace Practices............................................................................................................................................................23

Electronics Assembly Shops ................................................................................................................................ 24

Technologies That Eliminate or Reduce Risks from TCE......................................................................................25

Protecting Workers from TCE..........................................................................................................................................28

Workplace Practices............................................................................................................................................................29

References..................................................................................................................................................................... 31

Table 1.Degreasing Methods Commonly Used at Shops

Type of Shop

Degreasing Method

Spot Cleaning Cold Cleaning Vapor 

Degreasing

Repair shops X X X

Fabrication shops X X

Metal plating shops X X

Electronics assembly shops X X
Background Document | 3

Personal Protective Equipment When Using TCE

IF YOU USE TCE-based degreasers, you should always wear proper personal protective equipment (PPE). 

Effective types of PPE are described below.

Skin Protection

TCE can absorb through your skin, which can potentially be hazardous (NJDH, 2008) . Solvent-resistant 

gloves that can be effective against TCE include (NJDH, 2008):*

• Silver Shield®/4H® gloves

• Viton® fluoroelastomer gloves

• Barrier® model gloves

Gloves cannot permanently protect you from exposure to solvents. It is important to remove and replace 

your gloves when they become wet with TCE. Wear long sleeves to protect your skin. Coveralls can provide 

good skin protection for most of your body. Coveralls resemble jumpsuits and cover your torso, legs, and 

arms, and can even have attached hoods. Coverall brands that can effectively protect against TCE include 

(NJDH, 2008):*

• Tychem® F, BR, LV, Responder®, and TK coveralls

• Zytron® 500 coveralls

• ONESuit® TEC coveralls

• Trellchem® HPS and VPS coveralls

If you get TCE on your skin, immediately wash the contaminated area with water and soap. Provide a hand 

washing station, with soap or soap solution dispensers, near every cleaning or degreasing station.

Eye Protection

Wear chemical splash goggles (Figure 1) when using TCE to protect your eyes against any splashes. Wearing 

a chemical splash face shield (Figure 2) over your goggles can provide extra protection for your face. 

* Disclaimer of Endorsement: Reference herein to any specific commercial products, process, or service by trade name, trademark, 

manufacturer, or otherwise does not necessarily constitute or imply its endorsement, recommendation, or favoring by the United 

States Government.

Figure 1. Chemical splash goggles. Figure 2. Chemical splash face shield.
Background Document | 4

Personal Protective Equipment When Using TCE

Eye wash stations (Figure 3) should be provided near cleaning or degreasing stations. If you get TCE in your 

eyes, rinse them in the eye wash station immediately for at least 15 minutes to limit the damage to your eyes. 

Make sure the station is unobstructed so a worker can get to it quickly.

Respiratory Protection

If workers are overexposed to TCE vapors, and if you 

cannot use the methods discussed in the rest of this 

document to protect them, respirators may be needed. 

The most effective respirators for TCE are full-facepiece 

respirators with positive pressure supplied air or a self 

contained breathing apparatus (SCBA) (Figure 4). These 

types of respirators have an assigned protection factor 

(APF) of 10,000. This means workers using these types of 

respirators will inhale 10,000 times less TCE than workers 

wearing no respiratory protection at all (NIOSH, 2011).

Note that dust masks (N95 respirators) (Figure 5) do not 

protect against TCE.

X

Figure 4: Full-facepiece respirator (with 

supplied air).

Figure 5: N95 respirators do not protect 

against TCE.

Figure 3. Eye wash station.
Background Document | 5

Repair Shops

REPAIR SHOPS take items such as automobiles, bicycles, or electronics apart to find and fix the cause 

of their malfunction. During repair, service item components are cleaned to remove anything that would 

compromise the item’s operation. The component may be cleaned in place or removed from the service item, 

then re-installed once cleaned. How technicians clean the components depends on what they are servicing. 

Repair shops most commonly use the following degreasing processes:

• Spot cleaning. The cleaner is sprayed directly onto components, or dabbed or soaked onto a rag that 

is used to wipe components clean. Usually, the cleaning solvent is applied in excess and then allowed 

to air-dry. The components can be cleaned in place or removed from the service item for more 

thorough cleaning. This cleaning method may occur at any type of repair shop.

• Cold cleaning. Components are removed from the service item and are cleaned by spraying, 

brushing, flushing, or immersion in a non-boiling (i.e., “cold”) solvent, as shown in Figure 6. They 

are then dried and reinstalled into the service item. This cleaning method is most often used at 

automotive repair shops.

• Vapor degreasing. Degreasing 

solvents are boiled to produce 

a hot vapor (Figure 7). 

Components are suspended 

just above the bath, where the 

condensation of hot vapors 

cleans them. They are then 

reinstalled in the service item. 

This cleaning method is most 

often used at electronics repair 

shops.

Receipt of

Service Item

Removal of

Service Components

Cleaning of

Service Components

SPOT CLEANING

Cleaned

Components

Reinstallation

of Cleaned

Components

COLD CLEANING VAPOR DEGREASING

Figure 6. Cold cleaning system used for cleaning components.
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Repair Shops

Technologies That Eliminate or Reduce Risks from TCE

Due to the variety of components and contaminants encountered at repair shops, it is difficult to identify 

specific alternatives that will work across all shops. Choosing the most suitable alternative will depend on 

the nature of the serviced components, their contaminants, and the needed level of cleaning. Further, the 

cleaning processes already in use at a given shop will determine what alternatives are available. To choose 

the most appropriate one, it is important to evaluate the current cleaning process first. This includes:

• The source of the contaminant. If the contamination occurs at the shop, consider changing the 

process to eliminate its source. This would eliminate the need for cleaning components. For example, 

electronics repair shops can eliminate the need for cleaning by using a low-solids flux instead of a 

conventional rosin flux (as discussed below).

• The types of components that must be cleaned—specifically the materials of construction (carbon 

steel, stainless steel, aluminum, etc.), type of surface (textured or smooth), and shape (simple or 

complex).

• The types of contaminants that must be removed (heavy oils, light oils, greases, waxes, dirt, salts, 

etc.).

• The extent of cleaning needed. Determine the minimum cleanliness specifications for your 

components. Make sure you do not apply more cleaner than is necessary.

Once you have evaluated these factors for the shop’s cleaning method, work with vendors to determine 

which alternatives would best meet your cleaning needs.

Low-Solids Fluxes

This alternative is specific to electronics repair shops. Low-solids fluxes are used in the same way as 

conventional fluxes. However, their residues dry rapidly, leaving behind little or no residues on the circuit 

boards; this eliminates the need for solvent cleaning.

Figure 7. Vapor degreasing system used for cleaning components.
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Repair Shops

The successful application of low-solids fluxes will depend on the specific needs of the component being 

serviced. For some components, even trace amounts of residues will compromise the reliability of repaired 

electronics (EPA, 1996); therefore, these fluxes should only be used in servicing electrical components that 

are less sensitive to any remaining flux residues.

Bake-Off Ovens

This alternative is specific to automobile, motorcycle, or bicycle repair shops. Bake-off ovens can be used as 

an alternative to TCE degreasers. These ovens are designed to decompose dirt and grease, leaving behind 

a dry residue that can be brushed off. Bake-off ovens produce a smaller volume of waste compared to 

liquid cleaning alternatives (EPA, 1991). However, these systems can only be used on components that can 

withstand high heat.

Water-Based Cleaning

This alternative, which applies to any type of shop, substitutes the use of solvents with water-based 

chemistries. The degree of substitution can range from completely eliminating solvents (i.e., aqueous 

cleaning) to partially eliminating solvents (i.e., semi-aqueous cleaning). Water-based cleaning solutions 

can include various cleaning ingredients such as acid or alkaline chemicals, detergents, water conditioners, 

corrosion inhibitors, and foam stabilizers (PPRC, 1996a). Components can be cleaned using the following 

methods:

• Manual cleaning, in which water-based cleaning solutions are sprayed or wiped onto components 

and brushed clean.

• Hot soap washing, also known as hot tank washing, in which components are immersed in a 

heated aqueous detergent. The system is automated and uses air and mechanical agitation to more 

thoroughly clean components.

• Spray cleaning, in which components are placed in an enclosed chamber and sprayed with the 

cleaning solution using high-pressure jets (Figure 8).

• Ultrasonic cleaning, in which components are immersed in the cleaning solution and subjected to 

high-frequency sound waves that form bubbles on the surface of the components (Figure 9). The 

bubbles create a mechanical cleaning action.

Figure 8. Spray cleaner that uses an enclosed chamber to prevent worker exposures to the 

cleaning solution.
Background Document | 8

Repair Shops

Closed-Loop Vapor Degreasers

This alternative is specific to electronics repair shops. If substitution of TCE is not possible for vapor 

degreasing operations, consider installing a closed-loop vapor degreaser (Figure 10). This system cleans 

components in an air-tight chamber, which significantly reduces emissions and can also improve cleaning 

and product quality. Once the components are cleaned, vapors are exhausted to the outdoors before the 

chamber door can be opened. After the vapors are exhausted, workers can open the door and remove the 

cleaned components. Compared to conventional open-top vapor degreasers, closed-loop vapor degreasers 

can reduce vapor emissions by as much as 98 percent (NEWMOA, 2001).

Protecting Workers from TCE

In protecting your workers, you’ll use engineering controls—protective practices involving technologies and 

equipment. If it is not possible to eliminate the use of TCE from your cleaning operation, consider installing 

Figure 9. Ultrasonic cleaning tank.

Figure 10. Closed-loop vapor degreaser.
Background Document | 9

Repair Shops

engineering controls. The control options that apply to repair shops will depend on the type of degreasing 

system used at the shop.

The control options listed below will protect workers either by:

• Limiting how much TCE gets released directly into the workplace before it comes into contact with 

workers; or

• Limiting how much contact the workers have with TCE after it has been released into the workplace.

Generally speaking, the first approach is most desirable, as it not only limits the potential for worker 

exposures but also the potential for releases into the environment.

For spot cleaners, the engineering controls listed below focus primarily on limiting how much contact 

workers have with TCE after it has been applied to service item components. Because of the direct nature of 

spot cleaning, where TCE is sprayed or dabbed directly onto components, there are limited opportunities for 

introducing technologies or equipment that can reduce TCE releases into the workplace before it comes into 

contact with workers.

For cold cleaners and vapor degreasers, the engineering controls listed below focus primarily on limiting how 

much TCE gets released directly into the workplace before it comes into contact with workers. Some options 

are available for limiting worker exposures to TCE after it is released into the workplace, but they are limited 

to the installation of exhaust systems.

Spot Cleaners

• Isolate cleaning activities—physically separate the cleaning station from the rest of the shop.

• Use ventilation to remove vapors from the cleaning station. There are two types:

—General mechanical ventilation involves the removal (exhaust) of dirty air and the supply of fresh 

air within the building. In repair shops, it is often provided by the building’s heating, ventilation, 

and air conditioning (HVAC) system. The fresh, make-up air should enter on the opposite side of 

the room from the exhaust vents. It should be provided by outside air and not by air from other 

parts of the building. The exhaust air should exhaust to the outside of the building.

—Local exhaust ventilation provides exhaust ventilation close to the cleaning station. It captures 

and removes TCE vapors at the source before they enter the air inside the shop. Local exhaust 

ventilation should exhaust to the outside and not to other parts of the shop.

Cold Cleaners

• For open cleaning tanks, install a vapor-tight cover to limit the escape of solvent vapors whenever 

components are not being cleaned. Rolling covers are preferable over hinged covers, since hinged 

covers can force the escape of TCE vapors when they swing closed.

• Cover the solvent bath with a layer of water that is 2 to 4 inches thick. This water cover will float over 

the solvent bath and limit the amount of TCE that evaporates out of the bath and into the workplace 

(EPA, 1981).

• If using spray equipment, consider using a solid-fluid stream sprayer. Spray pressures should not 

exceed 10 pounds per square inch (psi) to avoid unnecessary misting of the cleaning solvent (KSUPPI, 

2010). Avoid using atomizing or shower-type sprayers, which can generate more vapors.

• For cleaning tanks with surface areas exceeding 10 square feet, install a lateral exhaust system (MM, 

no date). The exhaust should pass through a carbon adsorption unit to reduce the amount of solvent 
Background Document | 10

Repair Shops

that exhausts to the outdoors. Under no circumstances should the exhaust system re-circulate back 

into the workplace.

Vapor Degreasers

• For open-top degreasers, install a vapor-tight cover to limit the escape of solvent vapors when 

components are not being cleaned. Rolling covers are preferable over hinged covers, since hinged 

covers can force the escape of TCE vapors when they swing closed.

• Install a condenser coolant thermostat switch. This switch will automatically shut off the heater 

whenever the coolant temperature exceeds the maximum recommended by the equipment 

manufacturer.

• Install a solvent level control switch. This switch will automatically shut off the heater whenever the 

liquid level drops below the minimum recommended by the equipment manufacturer. 

• Install a vapor level control switch. This switch will automatically shut off the heater whenever the 

vapor level rises above the maximum height recommended by the equipment manufacturer.

• Install a second set of cooling coils. Known as “freeboard chillers,” these coils prevent vapors from 

escaping into the workplace. Note that freeboard chillers are not the same as the primary cooling 

coils that may already be installed in your vapor degreaser. The primary cooling coils are used to 

adjust the vapor height within the degreaser. They do not provide the same level of protection from 

vapors as freeboard chillers.

• For air-tight or air-less degreasing systems, install a differential pressure gauge. This gauge can be 

used to verify that the system is not leaking.

• For cleaning tanks with surface areas exceeding 10 square feet, install a lateral exhaust system (MM, 

no date). The exhaust should pass through a carbon adsorption unit to reduce the amount of solvent 

that exhausts to the outdoors. Under no circumstances should the exhaust system re-circulate back 

into the workplace.

Workplace Practices

If it is not possible to eliminate the use of TCE from your cleaning operation, consider implementing the 

following work practices and administrative controls:

Spot Cleaners

• Establish guidelines on when it is absolutely necessary to clean components with TCE; prohibit its use 

otherwise.

• Encourage or require employees to brush or scrape dirty components to remove caked-on solids. 

This will improve cleaning efficiency and reduce the amount of cleaner needed for spot cleaning.

Cold Cleaners and Vapor Degreasers

• Cold cleaning or vapor degreasing should never take place in the same room as soldering operations. 

Soldering operations generate intense heat that can decompose the solvent vapors to produce 

phosgene, a gas that is even more toxic than TCE (NOHSC, 1989).

• Cold cleaners and vapor degreasers should be situated in large, open locations with good general 

ventilation. These locations should be isolated from the rest of the shop.

• Cold cleaning and vapor degreasing equipment should only be used in accordance with the 

equipment manufacturer’s specifications.
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Repair Shops

• Vapor-tight covers should be closed at all times except during entry and removal of components.

• When the cover is open, avoid subjecting the tank to direct drafts, particularly from standing fans or 

ventilation ducts. These drafts can carry TCE vapors into surrounding work areas.

• For cold cleaners, maintain a freeboard ratio of 75 percent or more. For vapor degreasers, maintain 

a freeboard ratio of 100 percent. The freeboard ratio is equal to the height from the solvent surface 

to the top of the machine divided by the inside length or width of the tank (whichever is greater) 

(KSUPPI, 2010).

• Do not fill the cold cleaning or vapor degreasing tank beyond the fill line.

• Rack components in a manner that minimizes drag-out losses. For example, cup-shaped components 

should be inverted on the rack.

• Drain cleaned components for at least 15 seconds or until dripping stops. This will limit the escape of 

solvent vapors and allow the drained solvent to be recycled back into the cleaning or degreasing tank 

(KSUPPI, 2010).

• Waste solvents from cold cleaners and vapor degreasers should be collected and stored in closed 

containers to keep TCE from evaporating into the workplace. The containers should be properly 

labeled and managed in accordance with hazardous waste regulations.

• Workers should avoid leaning over a cold cleaning or vapor degreasing tank. Where necessary, use a 

hoist to move components in or out of the tank.

• Avoid overloading vapor degreasers. The solvent level should not drop by more than 4 inches when 

components are added (KSUPPI, 2010). The introduction of heavy loads will collapse the existing 

vapor blanket and expel TCE vapors.

• If vapor leaks are detected, repair the vapor degreaser immediately or shut it down until repairs 

are made. 
Background Document | 12

Fabrication Shops

DURING product fabrication—particularly for products made from metal—contaminants such as chips, 

grease, oils, dust, dirt, and polishing pastes can compromise the integrity of the final, fabricated parts 

(NEWMOA, 2001). For this reason, fabricating shops use degreasers to remove these contaminants, 

particularly before assembling or painting the final product.

Fabrication shops most typically use the following degreasing processes:

• Cold cleaning. Fabricated parts are cleaned by spraying, brushing, flushing, or immersion in a nonboiling (i.e., “cold”) solvent, as shown in Figure 11.

Fabrication

of Parts Parts Cleaning Cleaned Parts Direct Sale or Installation 

into Final Products

VAPOR DEGREASING

COLD CLEANING

Figure 11. Cold cleaning system used for cleaning parts.
Background Document | 13

Fabrication Shops

• Vapor degreasing. Degreasing solvents are boiled to produce a hot vapor (Figure 12). Fabricated 

parts are suspended just above the bath, where the condensation of hot vapors cleans them. 

After cold cleaning or vapor degreasing, the fabricated parts are suspended on a rack to drain the solvent. 

Either of these two processes can be done in batches or as part of a conveyorized (i.e., automated) system. 

With batch work, workers manually load or unload fabricated parts directly into or out of the cleaning 

solvent. With conveyorized systems, fabricated parts are continuously loaded on a line that automatically 

passes them through cold cleaning or vapor degreasing equipment as well as the subsequent drying steps

Technologies That Eliminate or Reduce Risks from TCE

Due to the variety of surfaces and contaminants encountered at fabrication shops, it is difficult to identify 

specific alternatives that will work across all shops. Choosing the most suitable alternative will depend on the 

nature of the fabricated parts, their contaminants, and the needed level of cleaning. Further, shops that use 

cold cleaners have a different set of alternatives than shops that use vapor degreasers. To choose the most 

appropriate alternative, it is important to evaluate the current cleaning process first. This includes:

• The source of the contaminant. If the contamination occurs at the shop, consider changing the 

process to eliminate its source. This would eliminate the need for cleaning parts.

• The types of parts that must be cleaned—specifically the materials of construction (carbon steel, 

stainless steel, aluminum, etc.), type of surface (textured or smooth), and shape (simple or complex).

• The types of contaminants that must be removed (heavy oils, light oils, greases, waxes, dirt, salts, 

etc.).

• The extent of cleaning needed. Determine the minimum cleanliness specifications for your parts. 

Make sure you do not apply more cleaner than is necessary.

Once you have evaluated these factors for the shop’s cleaning process, work with vendors to determine 

which alternatives would best meet your cleaning needs.

Figure 12. Vapor degreasing system used for cleaning parts.
Background Document | 14

Fabrication Shops

Water-Based Cleaning

This alternative substitutes the use of solvents with water-based chemistries. The degree of substitution can 

range from completely eliminating solvents (i.e., aqueous cleaning) to partially eliminating solvents (i.e., 

semi-aqueous cleaning). Water-based cleaning solutions can include various cleaning ingredients such as 

acid or alkaline chemicals, detergents, water conditioners, corrosion inhibitors, and foam stabilizers (PPRC, 

1996a). Parts can be cleaned using the following methods:

• Mechanical cleaning, in which fabricated parts are immersed in the cleaning solution and brushed 

clean.

• Spray cleaning, in which fabricated parts are placed in an enclosed chamber and sprayed with the 

cleaning solution using high-pressure jets (Figure 13).

• Ultrasonic cleaning, in which fabricated parts are immersed in the cleaning solution and subjected to 

high-frequency sound waves that form bubbles on the surface of the parts (Figure 14). The bubbles 

create a mechanical cleaning action.

Figure 13. Spray cleaner that uses an enclosed chamber to prevent worker exposures to the cleaning 

solution.

Figure 14. Ultrasonic cleaning tank.
Background Document | 15

Fabrication Shops

Closed-Loop Vapor Degreasers

If substitution of TCE is not possible for vapor degreasing operations, consider installing a closed-loop vapor 

degreaser (Figure 15). This system cleans parts in an air-tight chamber, which significantly reduces emissions 

and can also improve cleaning and product quality. Once the parts are cleaned, vapors are exhausted to 

the outdoors before the chamber door can be opened. After the vapors are exhausted, workers can open 

the door and remove the cleaned parts. Compared to conventional open-top vapor degreasers, closed-loop 

vapor degreasers can reduce vapor emissions by as much as 98 percent (NEWMOA, 2001).

Closed-loop vapor degreasers can incorporate multi-stage processing to enhance cleaning operations. For 

example, systems are available that can immerse, flush, or spray parts before the vapor degreasing stage, or 

vice versa. These systems also can incorporate vacuum drying into the process, rather than relying solely on 

exhaust fans for drying. This not only reduces the drying time but also the potential for worker exposures, 

since it dries the cleaned parts more thoroughly.

Protecting Workers from TCE

In protecting your workers, you’ll use engineering controls—protective practices involving technologies 

and equipment. If it is not possible to eliminate the use of TCE from your cleaning operation, consider 

installing engineering controls. The control options that apply to fabrication shops will depend on the type of 

degreasing system used at the shop (i.e., cold cleaner vs. vapor degreaser).

The control options listed below will protect workers either by:

• Limiting how much TCE gets released directly into the workplace before it comes into contact with 

workers; or

• Limiting how much contact the workers have with TCE after it has been released into the workplace.

Generally speaking, the first approach is most desirable, as it not only limits the potential for worker 

exposures but also the potential for releases into the environment.

Figure 15. Closed-loop vapor degreaser.
Background Document | 16

Fabrication Shops

For cold cleaners and vapor degreasers, the engineering controls listed below focus primarily on limiting how 

much TCE gets released directly into the workplace before it comes into contact with workers. Some options 

are available for limiting worker exposures to TCE after it is released into the workplace, but they are limited 

to the installation of exhaust systems.

Cold Cleaners

• For open cleaning tanks, install a vapor-tight cover to limit the escape of solvent vapors whenever 

parts are not being cleaned. Rolling covers are preferable over hinged covers, since hinged covers can 

force the escape of TCE vapors when they swing closed.

• Cover the solvent bath with a layer of water that is 2 to 4 inches thick. This water cover will float 

over the solvent bath and will limit the amount of TCE that evaporates out of the bath and into the 

workplace (EPA, 1981).

• If using spray equipment, consider using a solid-fluid stream sprayer. Spray pressures should not 

exceed 10 pounds per square inch (psi) to avoid unnecessary misting of the cleaning solvent (KSUPPI, 

2010). Avoid using atomizing or shower-type sprayers, which can generate more vapors.

• For cleaning tanks with surface areas exceeding 10 square feet, install a lateral exhaust system (MM, 

no date). The exhaust should pass through a carbon adsorption unit to reduce the amount of solvent 

that exhausts to the outdoors. Under no circumstances should the exhaust system re-circulate back 

into the workplace.

• For conveyorized systems, install a drying tunnel or rotating/tumbling basket. This will reduce the 

amount of solvent liquid dragged out of the cleaning bath and reduce the amount of vapor that 

workers could inhale when removing parts from the basket.

• For conveyorized systems, minimize the size of the cleaning unit’s openings. The average clearance 

between cleaning parts and the edge of the cleaning unit’s opening should not exceed 10 percent of 

the opening’s width (KSUPPI, 2010).

Vapor Degreasers

• For open-top degreasers, install a vapor-tight cover to limit the escape of solvent vapors when parts 

are not being cleaned. Rolling covers are preferable over hinged covers, since hinged covers can force 

the escape of TCE vapors when they swing closed.

• Install a condenser coolant thermostat switch. This switch will automatically shut off the heater 

whenever the coolant temperature exceeds the maximum recommended by the equipment 

manufacturer.

• Install a solvent level control switch. This switch will automatically shut off the heater whenever the 

liquid level drops below the minimum recommended by the equipment manufacturer. 

• Install a vapor level control switch. This switch will automatically shut off the heater whenever the 

vapor level rises above the maximum height recommended by the equipment manufacturer.

• Install a second set of cooling coils. Known as “freeboard chillers,” these coils prevent vapors from 

escaping into the workplace. Note that freeboard chillers are not the same as the primary cooling 

coils that may already be installed in your vapor degreaser. The primary cooling coils are used to 

adjust the vapor height within the degreaser. They do not provide the same level of protection from 

vapors as freeboard chillers.

• For air-tight or airless degreasing systems, install a differential pressure gauge. This gauge can be 

used to verify that the system is not leaking.
Background Document | 17

Fabrication Shops

• For cleaning tanks with surface areas exceeding 10 square feet, install a lateral exhaust system (MM, 

no date). The exhaust should pass through a carbon adsorption unit in order to reduce the amount of 

solvent that exhausts to the outdoors. Under no circumstances should the exhaust system re-circulate 

back into the workplace.

• For conveyorized systems, install a drying tunnel or rotating/tumbling basket. This will reduce the 

amount of solvent liquid dragged out of the cleaning bath and reduce the amount of vapor that 

workers could inhale when removing parts from the basket.

• For conveyorized systems, minimize the size of the cleaning unit’s openings. The average clearance 

between cleaning parts and the edge of the cleaning unit’s opening should not exceed 10 percent of 

the opening’s width (KSUPPI, 2010).

Workplace Practices

If it is not possible to eliminate the use of TCE from your cold cleaning or vapor degreasing operation, 

consider implementing the following work practices and administrative controls:

• Cold cleaners and vapor degreasers should be situated in large, open locations with good general 

ventilation. These locations should be isolated from the rest of the shop.

• Cold cleaning and vapor degreasing equipment should only be used in accordance with the 

equipment manufacturer’s specifications.

• Vapor-tight covers should be closed at all times except during entry and removal of parts.

• When the cover is open, avoid subjecting the tank to direct drafts, particularly from standing fans or 

ventilation ducts. These drafts can carry TCE vapors into surrounding work areas.

• For cold cleaners, maintain a freeboard ratio of 75 percent or more. For vapor degreasers, maintain 

a freeboard ratio of 100 percent. The freeboard ratio is equal to the height from the solvent surface 

to the top of the machine divided by the inside length or width of the tank (whichever is greater) 

(KSUPPI, 2010).

• Do not fill the cold cleaning or vapor degreasing tank beyond the fill line.

• Rack fabricated parts in a manner that minimizes drag-out losses. For example, cup-shaped parts 

should be inverted on the rack.

• Drain cleaned parts for at least 15 seconds or until dripping stops. This will limit the escape of solvent 

vapors and allow the drained solvent to be recycled back into the cleaning or degreasing tank 

(KSUPPI, 2010).

• Waste solvents from cold cleaners and vapor degreasers should be collected and stored in closed 

containers to keep TCE from evaporating into the workplace. The containers should be properly 

labeled and managed in accordance with hazardous waste regulations.

• Workers should avoid leaning over a cold cleaning or vapor degreasing tank. Where necessary, use a 

hoist to move parts in or out of the tank.

• Avoid overloading vapor degreasers. The solvent level should not drop by more than 4 inches when 

parts are added (KSUPPI, 2010). The introduction of heavy loads will collapse the existing vapor 

blanket and expel TCE vapors.

• If vapor leaks are detected, repair the vapor degreaser immediately or shut it down until repairs are 

made.

• For conveyorized cold cleaning or vapor degreasing systems, limit the conveyor speed to no more 

than 11 feet per minute so that the cleaned parts have enough time to drain back into the bath 

(KSUPPI, 2010).
Background Document | 18

Metal Plating Shops

+ –

WHILE FABRICATED parts are being electroplated, contaminants such as grease, oils, dust, dirt, and 

polishing pastes can compromise the electroplated finish, causing cracking and pealing of the metal 

(NEWMOA, 2001). For this reason, metal plating shops use degreasers to clean the metal surface before 

electroplating.

Metal plating shops most typically use the following degreasing processes:

• Cold cleaning. Parts are cleaned by spraying, brushing, flushing, or immersion in a non-boiling 

(i.e., “cold”) solvent, as shown in Figure 16.

Receipt of

Fabricated Parts Parts Cleaning Parts

Electroplating Cleaned Parts Direct Sale of Plated Parts

or Final Products

VAPOR DEGREASING

COLD CLEANING

+ –

Figure 16. Cold cleaning system used for cleaning parts.
Background Document | 19

Metal Plating Shops

+ –

• Vapor degreasing. Degreasing solvents are boiled to produce a hot vapor (Figure 17). Parts are 

suspended just above the bath, where the condensation of hot vapors cleans them.

After cold cleaning or vapor degreasing, the parts are rinsed with water and placed in the electroplating 

bath, where the finishing metal is deposited onto the parts.

Either of these two processes can be done in batches or as part of a conveyorized (i.e., automated) system. 

With batch work, workers manually load or unload parts directly into or out of the cleaning solvent. With 

conveyorized systems, parts are continuously loaded on a line that automatically passes them through cold 

cleaning or vapor degreasing equipment as well as the subsequent rinsing, electroplating, and drying steps.

Technologies That Eliminate or Reduce Risks from TCE

Due to the variety of surfaces and contaminants encountered at metal plating shops, it is difficult to identify 

specific alternatives that will work across all shops. Choosing the most suitable alternative will depend on the 

nature of the metal plating parts, their contaminants, and the needed level of cleaning. Further, shops that 

use cold cleaners have a different set of alternatives than shops that use vapor degreasers. To choose the 

most appropriate alternative, it is important to evaluate the current cleaning process first. This includes:

• The source of the contaminant. If the contamination occurs at the shop, consider changing the 

process to eliminate its source. This would eliminate the need for cleaning parts.

• The types of parts that must be cleaned—specifically the materials of construction (carbon steel, 

stainless steel, aluminum, etc.), type of surface (textured or smooth), and shape (simple or complex). 

• The types of contaminants that must be removed (heavy oils, light oils, greases, waxes, dirt, salts, 

etc.). 

• The extent of cleaning needed. Determine the minimum cleanliness specifications for your parts. 

Make sure you do not apply more cleaner than is necessary.

Figure 17. Vapor degreasing system used for cleaning parts.
Background Document | 20

Metal Plating Shops

+ –

Once you have evaluated these factors for the shop’s cleaning process, work with vendors to determine 

which alternatives would best meet your cleaning needs. 

Water-Based Cleaning

This alternative substitutes the use of solvents with water-based chemistries. The degree of substitution can 

range from completely eliminating solvents (i.e., aqueous cleaning) to partially eliminating solvents (i.e., 

semi-aqueous cleaning). Water-based cleaning solutions can include various cleaning ingredients such as 

acid or alkaline chemicals, detergents, water conditioners, corrosion inhibitors, and foam stabilizers (PPRC, 

1996a). Parts can be cleaned using the following methods:

• Mechanical cleaning, in which metal plating parts are immersed in the cleaning solution and brushed 

clean.

• Spray cleaning, in which metal plating parts are sprayed with the cleaning solution using highpressure jets (Figure 18).

• Ultrasonic cleaning, in which metal plating parts are immersed in the cleaning solution and subjected 

to high-frequency sound waves that form bubbles on the surface of the parts (Figure 19). The bubbles 

create a mechanical cleaning action.

Figure 18. Spray cleaner that uses an enclosed chamber to prevent worker exposures to the cleaning 

solution.

Figure 19. Ultrasonic cleaning tank.
Background Document | 21

Metal Plating Shops

+ –

Closed-Loop Vapor Degreasers

If substitution of TCE is not possible for vapor degreasing operations, consider installing a closed-loop vapor 

degreaser (Figure 20). This system cleans parts in an air-tight chamber, which significantly reduces emissions 

and can also improve cleaning and product quality. Once the parts are cleaned, vapors are exhausted to 

the outdoors before the chamber door can be opened. After the vapors are exhausted, workers can open 

the door and remove the cleaned parts. Compared to conventional open-top vapor degreasers, closed-loop 

vapor degreasers can reduce vapor emissions by as much as 98 percent (NEWMOA, 2001).

Closed-loop vapor degreasers can incorporate multi-stage processing to enhance cleaning operations. For 

example, systems are available that can immerse, flush, or spray parts before the vapor degreasing stage, or 

vice versa. These systems also can incorporate vacuum drying into the process, rather than relying solely on 

exhaust fans for drying. This not only reduces the drying time but also the potential for worker exposures, 

since it dries the cleaned parts more thoroughly.

Protecting Workers from TCE

In protecting your workers, you’ll use engineering controls—protective practices involving technologies and 

equipment. If it is not possible to eliminate the use of TCE from your cleaning operation, consider installing 

engineering controls. The control options that apply to metal plating shops will depend on the type of 

degreasing system used at the shop (i.e., cold cleaner vs. vapor degreaser). 

The control options listed below will protect workers either by:

• Limiting how much TCE gets released directly into the workplace before it comes into contact with 

workers; or

• Limiting how much contact the workers have with TCE after it has been released into the workplace.

Generally speaking, the first approach is most desirable, as it not only limits the potential for worker 

exposures but also the potential for releases into the environment.

Figure 20. Closed-loop vapor degreaser.
Background Document | 22

Metal Plating Shops

+ –

For cold cleaners and vapor degreasers, the engineering controls listed below focus primarily on limiting how 

much TCE gets released directly into the workplace before it comes into contact with workers. Some options 

are available for limiting worker exposures to TCE after it is released into the workplace, but they are limited 

to the installation of exhaust systems.

Cold Cleaners

• For open cleaning tanks, install a vapor-tight cover to limit the escape of solvent vapors whenever 

parts are not being cleaned. Rolling covers are preferable over hinged covers, since hinged covers can 

force the escape of TCE vapors when they swing closed.

• Cover the solvent bath with a layer of water that is 2 to 4 inches thick. This water cover will float 

over the solvent bath and will limit the amount of TCE that evaporates out of the bath and into the 

workplace (EPA, 1981).

• If using spray equipment, consider using a solid-fluid stream sprayer. Spray pressures should not 

exceed 10 pounds per square inch (psi) to avoid unnecessary misting of the cleaning solvent (KSUPPI, 

2010). Avoid using atomizing or shower-type sprayers, which can generate more vapors.

• For cleaning tanks with surface areas exceeding 10 square feet, install a lateral exhaust system (MM, 

no date). The exhaust should pass through a carbon adsorption unit in order to reduce the amount of 

solvent that exhausts to the outdoors. Under no circumstances should the exhaust system re-circulate 

back into the workplace.

• For conveyorized systems, install a drying tunnel or rotating/tumbling basket. This will reduce the 

amount of solvent liquid dragged out of the cleaning bath and reduce the amount of vapor that 

workers could inhale when removing parts from the basket.

• For conveyorized systems, minimize the size of the cleaning unit’s openings. The average clearance 

between cleaning parts and the edge of the cleaning unit’s opening should not exceed 10 percent of 

the opening’s width (KSUPPI, 2010).

Vapor Degreasers

• For open-top degreasers, install a vapor-tight cover to limit the escape of solvent vapors when parts 

are not being cleaned. Rolling covers are preferable over hinged covers, since hinged covers can force 

the escape of TCE vapors when they swing closed.

• Install a condenser coolant thermostat switch. This switch will automatically shut off the heater 

whenever the coolant temperature exceeds the maximum recommended by the equipment 

manufacturer.

• Install a solvent level control switch. This switch will automatically shut off the heater whenever the 

liquid level drops below the minimum recommended by the equipment manufacturer. 

• Install a vapor level control switch. This switch will automatically shut off the heater whenever the 

vapor level rises above the maximum height recommended by the equipment manufacturer.

• Install a second set of cooling coils. Known as “freeboard chillers,” these coils prevent vapors from 

escaping into the workplace. Note that freeboard chillers are not the same as the primary cooling 

coils that may already be installed in your vapor degreaser. The primary cooling coils are used to 

adjust the vapor height within the degreaser. They do not provide the same level of protection from 

vapors as freeboard chillers.

• For air-tight or air-less degreasing systems, install a differential pressure gauge. This gauge can be 

used to verify that the system is not leaking.
Background Document | 23

Metal Plating Shops

+ –

• For cleaning tanks with surface areas exceeding 10 square feet, install a lateral exhaust system (MM, 

no date). The exhaust should pass through a carbon adsorption unit in order to reduce the amount of 

solvent that exhausts to the outdoors. Under no circumstances should the exhaust system re-circulate 

back into the workplace.

• For conveyorized systems, install a drying tunnel or rotating/tumbling basket. This will reduce the 

amount of solvent liquid dragged out of the cleaning bath and reduce the amount of vapor that 

workers could inhale when removing parts from the basket.

• For conveyorized systems, minimize the size of the cleaning unit’s openings. The average clearance 

between cleaning parts and the edge of the cleaning unit’s opening should not exceed 10 percent of 

the opening’s width (KSUPPI, 2010).

Workplace Practices

If it is not possible to eliminate the use of TCE from your cold cleaning or vapor degreasing operation, 

consider implementing the following work practices and administrative controls:

• Cold cleaners and vapor degreasers should be situated in large, open locations with good general 

ventilation. These locations should be isolated from the rest of the shop.

• Cold cleaning and vapor degreasing equipment should only be used in accordance with the 

equipment manufacturer’s specifications.

• Vapor-tight covers should be closed at all times except during entry and removal of parts.

• When the cover is open, avoid subjecting the tank to direct drafts, particularly from standing fans or 

ventilation ducts. These drafts can carry TCE vapors into surrounding work areas.

• For cold cleaners, maintain a freeboard ratio of 75 percent or more. For vapor degreasers, maintain 

a freeboard ratio of 100 percent. The freeboard ratio is equal to the height from the solvent surface 

to the top of the machine divided by the inside length or width of the tank (whichever is greater) 

(KSUPPI, 2010).

• Do not fill the cold cleaning or vapor degreasing tank beyond the fill line.

• Rack parts in a manner that minimizes drag-out losses. For example, cup-shaped parts should be 

inverted on the rack.

• Drain cleaned parts for at least 15 seconds or until dripping stops. This will limit the escape of solvent 

vapors and allow the drained solvent to be recycled back into the cleaning or degreasing tank 

(KSUPPI, 2010).

• Waste solvents from cold cleaners and vapor degreasers should be collected and stored in closed 

containers to keep TCE from evaporating into the workplace. The containers should be properly 

labeled and managed in accordance with hazardous waste regulations.

• Workers should avoid leaning over a cold cleaning or vapor degreasing tank. Where necessary, use a 

hoist to move parts in or out of the tank.

• Avoid overloading vapor degreasers. The solvent level should not drop by more than 4 inches when 

parts are added (KSUPPI, 2010). The introduction of heavy loads will collapse the existing vapor 

blanket and expel TCE vapors.

• If vapor leaks are detected, repair the vapor degreaser immediately or shut it down until repairs are 

made.

• For conveyorized cold cleaning or vapor degreasing systems, limit the conveyor speed to no more 

than 11 feet per minute so that the cleaned parts have enough time to drain back into the bath 

(KSUPPI, 2010).
Background Document | 24

Electronics Assembly Shops

DURING ELECTRONICS ASSEMBLY, electronic components are attached to a circuit board and soldered 

in place, permanently connecting them to the board. Just before soldering, flux is applied to the board to 

clean the surface and to prevent contamination during soldering. The flux is then cleaned from the board 

using TCE.

Electronics assembly shops most typically use the following degreasing processes:

• Cold cleaning. Electronics are cleaned by spraying, brushing, flushing, or immersion in a non-boiling 

(i.e., “cold”) solvent, as shown in Figure 21.

Fabrication of

Circuit Board

Assemblies

Circuit Board

Assembly Cleaning

Cleaned Circuit

Board Assemblies

Direct Sale or Installation

Into Final Products

VAPOR DEGREASING

COLD CLEANING

Figure 21. Cold cleaning system used for cleaning components.
Background Document | 25

Electronics Assembly Shops

• Vapor degreasing. DDegreasing solvents are boiled to produce a hot vapor (Figure 22). Electronics 

are suspended just above the bath, where the condensation of hot vapors cleans them. 

After cold cleaning or vapor degreasing, the components are dried and assembled to produce the finished 

electronic device.

Either of these two processes can be done in batches or as part of a conveyorized (i.e., automated) system. 

With batch work, workers manually load or unload components directly into or out of the cleaning solvent. 

With conveyorized systems, components are continuously loaded on a line that automatically passes them 

through cold cleaning or vapor degreasing equipment as well as the subsequent drying steps.

Technologies That Eliminate or Reduce Risks from TCE

Due to the variety of components and contaminants encountered at electronics assembly shops, it is difficult 

to identify specific alternatives that will work across all shops. Choosing the most suitable alternative will 

depend on the nature of the electronic assemblies, their contaminants, and the needed level of cleaning. 

Further, the cleaning processes already in use at a given shop will determine what alternatives are available. 

To choose the most appropriate alternative, it is important to evaluate the current cleaning process first. This 

includes:

• The source of the contaminant. If the contamination occurs at the shop, consider changing the 

process to eliminate its source. This would eliminate the need for cleaning components.

• The types of parts that must be cleaned—specifically the type of surface (textured or smooth) and 

shape (simple or complex). 

• The types of contaminants that must be removed (heavy oils, light oils, greases, waxes, dirt, 

salts, etc.). 

• The extent of cleaning needed. Determine the minimum cleanliness specifications for your 

components. Make sure you do not apply more cleaner than is necessary.

Figure 22. Vapor degreasing system used for cleaning components.
Background Document | 26

Electronics Assembly Shops

Once you have evaluated these factors for the shop’s cleaning process, work with vendors to determine 

which alternatives would best meet your cleaning needs. 

Low-Solids Fluxes

Low-solids fluxes are used in the same way as conventional fluxes. However, their residues dry rapidly, 

leaving behind little or no residues on the circuit boards; this eliminates the need for solvent cleaning. The 

successful application of low-solids fluxes will depend on the specific needs of the electronic component 

being assembled. For some components, even trace amounts of residues will compromise the reliability of 

the electronics (EPA, 1996); therefore, these fluxes should only be used on components that are not sensitive 

to flux residues.

Inert Atmosphere Soldering

In inert atmosphere soldering, the soldering station is placed in an oxygen-free environment—typically 

nitrogen gas. The inert environment prevents the production of oxide contaminants during soldering, thereby 

eliminating the need for any flux or subsequent solvent cleaning steps. As with low-solids flux technology, 

the suitability of inert atmosphere soldering depends on the specific needs of the electronic component 

being assembled, as some components can still require flux before soldering even if an inert environment is 

used (EPA, 1994).

Water-Based Cleaning

This alternative substitutes the use of solvents with water-based chemistries. The degree of substitution can 

range from completely eliminating solvents (i.e., aqueous cleaning) to partially eliminating solvents (i.e., 

semi-aqueous cleaning). Water-based cleaning solutions can include various cleaning ingredients such as 

acid or alkaline chemicals, detergents, water conditioners, corrosion inhibitors, and foam stabilizers (PPRC, 

1996a). Components can be cleaned using the following methods:

• Mechanical cleaning, in which electronic components are immersed in the cleaning solution and 

brushed clean.

• Spray cleaning, in which components are placed in an enclosed chamber and sprayed with the 

cleaning solution using high-pressure jets (Figure 23).

Figure 23. Spray cleaner that uses an enclosed chamber to prevent worker exposures to the cleaning 

solution.
Background Document | 27

Electronics Assembly Shops

• Ultrasonic cleaning, in which electronic components are immersed in the cleaning solution and 

subjected to high-frequency sound waves that form bubbles on the surface of the components 

(Figure 24). The bubbles create a mechanical cleaning action.

Closed-Loop Vapor Degreasers

If substitution of TCE is not possible for vapor degreasing operations, consider installing a closed-loop vapor 

degreaser (Figure 25). This system cleans components in an air-tight chamber, which significantly reduces 

emissions and can also improve cleaning and product quality. Once the components are cleaned, vapors 

are exhausted to the outdoors before the chamber door can be opened. After the vapors are exhausted, 

workers can open the door and remove the cleaned components. Compared to conventional open-top vapor 

degreasers, closed-loop vapor degreasers can reduce vapor emissions by as much as 98 percent (NEWMOA, 

2001).

Closed-loop vapor degreasers can incorporate multi-stage processing to enhance cleaning operations. For 

example, systems are available that can immerse, flush, or spray components before the vapor degreasing 

stage, or vice versa. These systems also can incorporate vacuum drying into the process, rather than relying 

solely on exhaust fans for drying. This not only reduces the drying time but also the potential for worker 

exposures, since it dries the cleaned components more thoroughly.

Figure 24. Ultrasonic cleaning tank.

Figure 25. Closed-loop vapor degreaser.
Background Document | 28

Electronics Assembly Shops

Protecting Workers from TCE

In protecting your workers, you’ll use engineering controls—protective practices involving technologies and 

equipment. If it is not possible to eliminate the use of TCE from your cleaning operation, consider installing 

engineering controls. The control options that apply to electronics assembly shops will depend on the type of 

degreasing system used at the shop (i.e., cold cleaner vs. vapor degreaser). 

The control options listed below will protect workers either by:

• Limiting how much TCE gets released directly into the workplace before it comes into contact with 

workers; or

• Limiting how much contact the workers have with TCE after it has been released into the workplace.

Generally speaking, the first approach is most desirable, as it not only limits the potential for worker 

exposures but also the potential for releases into the environment.

For cold cleaners and vapor degreasers, the engineering controls listed below focus primarily on limiting how 

much TCE gets released directly into the workplace before it comes into contact with workers. Some options 

are available for limiting worker exposures to TCE after it is released into the workplace, but they are limited 

to the installation of exhaust systems.

Cold Cleaners

• For open cleaning tanks, install a vapor-tight cover to limit the escape of solvent vapors whenever 

components are not being cleaned. Rolling covers are preferable over hinged covers, since hinged 

covers can force the escape of TCE vapors when they swing closed.

• Cover the solvent bath with a layer of water that is 2 to 4 inches thick. This water cover will float 

over the solvent bath and will limit the amount of TCE that evaporates out of the bath and into the 

workplace (EPA, 1981).

• If using spray equipment, consider using a solid-fluid stream sprayer. Spray pressures should not 

exceed 10 pounds per square inch (psi) to avoid unnecessary misting of the cleaning solvent (KSUPPI, 

2010). Avoid using atomizing or shower-type sprayers, which can generate more vapors.

• For cleaning tanks with surface areas exceeding 10 square feet, install a lateral exhaust system (MM, 

no date). The exhaust should pass through a carbon adsorption unit in order to reduce the amount of 

solvent that exhausts to the outdoors. Under no circumstances should the exhaust system re-circulate 

back into the workplace.

• For conveyorized systems, install a drying tunnel or rotating/tumbling basket. This will reduce the 

amount of solvent liquid dragged out of the cleaning bath and reduce the amount of vapor that 

workers could inhale when removing components from the basket.

• For conveyorized systems, minimize the size of the cleaning unit’s openings. The average clearance 

between cleaning components and the edge of the cleaning unit’s opening should not exceed 10 

percent of the opening’s width (KSUPPI, 2010).

Vapor Degreasers

• For open-top degreasers, install a vapor-tight cover to limit the escape of solvent vapors when 

components are not being cleaned. Rolling covers are preferable over hinged covers, since hinged 

covers can force the escape of TCE vapors when they swing closed.

• Install a condenser coolant thermostat switch. This switch will automatically shut off the heater 

whenever the coolant temperature exceeds the maximum recommended by the equipment 

manufacturer.
Background Document | 29

Electronics Assembly Shops

• Install a solvent level control switch. This switch will automatically shut off the heater whenever the 

liquid level drops below the minimum recommended by the equipment manufacturer. 

• Install a vapor level control switch. This switch will automatically shut off the heater whenever the 

vapor level rises above the maximum height recommended by the equipment manufacturer.

• Install a second set of cooling coils. Known as “freeboard chillers,” these coils prevent vapors from 

escaping into the workplace. Note that freeboard chillers are not the same as the primary cooling 

coils that may already be installed in your vapor degreaser. The primary cooling coils are used to 

adjust the vapor height within the degreaser. They do not provide the same level of protection from 

vapors as freeboard chillers.

• For air-tight or air-less degreasing systems, install a differential pressure gauge. This gauge can be 

used to verify that the system is not leaking.

• For cleaning tanks with surface areas exceeding 10 square feet, install a lateral exhaust system (MM, 

no date). The exhaust should pass through a carbon adsorption unit to reduce the amount of solvent 

that exhausts to the outdoors. Under no circumstances should the exhaust system re-circulate back 

into the workplace.

• For conveyorized systems, install a drying tunnel or rotating/tumbling basket. This will reduce the 

amount of solvent liquid dragged out of the cleaning bath and reduce the amount of vapor that 

workers could inhale when removing components from the basket.

• For conveyorized systems, minimize the size of the cleaning unit’s openings. The average clearance 

between cleaning components and the edge of the cleaning unit’s opening should not exceed 10 

percent of the opening’s width (KSUPPI, 2010).

Workplace Practices

If it is not possible to eliminate the use of TCE from your cold cleaning or vapor degreasing operation, 

consider implementing the following work practices and administrative controls:

• Cold cleaning or vapor degreasing should never take place in the same room as soldering operations. 

Soldering operations generate intense heat that can decompose the solvent vapors to produce 

phosgene, a gas that is even more toxic than TCE (NOHSC, 1989).

• Cold cleaners and vapor degreasers should be situated in large, open locations with good general 

ventilation. These locations should be isolated from the rest of the shop.

• Cold cleaning and vapor degreasing equipment should only be used in accordance with the 

equipment manufacturer’s specifications.

• Vapor-tight covers should be closed at all times except during entry and removal of components.

• When the cover is open, avoid subjecting the tank to direct drafts, particularly from standing fans or 

ventilation ducts. These drafts can carry TCE vapors into surrounding work areas.

• For cold cleaners, maintain a freeboard ratio of 75 percent or more. For vapor degreasers, maintain 

a freeboard ratio of 100 percent. The freeboard ratio is equal to the height from the solvent surface 

to the top of the machine divided by the inside length or width of the tank (whichever is greater) 

(KSUPPI, 2010).

• Do not fill the cold cleaning or vapor degreasing tank beyond the fill line.

• Rack components in a manner that minimizes drag-out losses. For example, cup-shaped components 

should be inverted on the rack.
Background Document | 30

Electronics Assembly Shops

• Drain cleaned components for at least 15 seconds or until dripping stops. This will limit the escape of 

solvent vapors and allow the drained solvent to be recycled back into the cleaning or degreasing tank 

(KSUPPI, 2010).

• Waste solvents from cold cleaners and vapor degreasers should be collected and stored in closed 

containers to keep TCE from evaporating into the workplace. The containers should be properly 

labeled and managed in accordance with hazardous waste regulations.

• Workers should avoid leaning over a cold cleaning or vapor degreasing tank. Where necessary, use a 

hoist to move components in or out of the tank.

• Avoid overloading vapor degreasers. The solvent level should not drop by more than 4 inches when 

components are added (KSUPPI, 2010). The introduction of heavy loads will collapse the existing 

vapor blanket and expel TCE vapors.

• If vapor leaks are detected, repair the vapor degreaser immediately or shut it down until repairs are 

made.

• For conveyorized cold cleaning or vapor degreasing systems, limit the conveyor speed to no more 

than 11 feet per minute so that the cleaned components have enough time to drain back into the bath 

(KSUPPI, 2010). 
Background Document | 31

References

(ATSDR, 1997) Toxicological Profile for Trichloroethylene. U.S. Agency for Toxic Substances and Disease 

Registry, Division of Toxicology, Toxicology Information Branch, Atlanta, GA. 1997. 

Available at: www.epa.gov/iris/supdocs/0199index.html.

(EPA, no date) Evaluation of Alternatives to Chlorinated Solvents for Metal Cleaning. U.S. Environmental 

Protection Agency. No date.

(EPA, 1981) Solvent Degreasing. AP-42 – Compilation of Air Pollutant Emission Factors. Vol. 1. Fifth 

Ed. U.S. Environmental Protection Agency. 1981.

(EPA, 1991) Guides to Pollution Prevention—The Automotive Repair Industry. U.S. Environmental 

Protection Agency. 1991.

(EPA, 1994) Guide to Cleaner Technologies—Cleaning and Degreasing Process Changes. U.S. 

Environmental Protection Agency. 1994.

(EPA, 1996) Pollution Prevention in the Electronics Industry. U.S. Environmental Protection Agency. 

1996.

(EPA, 2001) Guide to Industrial Assessments for Pollution Prevention and Energy Efficiency. U.S. 

Environmental Protection Agency. 2001.

(EPA, 2011) Toxicological Review of Trichloroethylene (CAS No. 79-01-6). EPA/635/R-09/011F. 

U.S. Environmental Protection Agency, Integrated Risk Information System, Office of 

Research and Development, Washington, DC. 2011. Available at: www.epa.gov/iris/

supdocs/0199index.html.

(HSIA, no date) Trichloroethylene. Halogenated Solvents Industry Alliance. No date.

(KSUPPI, no date a) Pollution Prevention for the Automotive Maintenance and Repair Industry. Kansas State 

University Pollution Prevention Institute. No date.

(KSUPPI, no date b) Pollution Prevention for the Electroplating and Metal Finishing Industry. Kansas State 

University Pollution Prevention Institute. No date.

(KSUPPI, 2010) The Smell of Success: Decreasing Air Pollution in the Kansas City Area. Kansas State 

University Pollution Prevention Institute. 2010.

(MM, no date) Guidelines on Solvent Degreasing. Singapore Ministry of Manpower. No date. Available 

at: www.mom.gov.sg/Documents/safety-health/factsheets-circulars/Solvent%20

Degreasing.pdf.

(NEWMOA, 2001) Pollution Prevention Technology Profile – Closed Loop Vapor Degreasing. Northeast 

Waste Management Officials’ Association. 2001.

(NIOSH, 2011) Trichloroethylene. NIOSH Pocket Guide to Chemical Hazards. National Institute for 

Occupational Safety and Health. 2011. Available at: www.cdc.gov/niosh/npg/npgd0629.

html.

(NJDH, 2008) Right to Know Hazardous Substance Fact Sheet: Trichloroethylene. New Jersey 

Department of Health. 2008. Available at: http://nj.gov/health/eoh/rtkweb/documents/

fs/1890.pdf.
Background Document | 32

References

(NOHSC, 1989) Solvent Vapor Degreasing. Australia National Occupational Health and Safety 

Commission. 1989. Available at: www.safeworkaustralia.gov.au/sites/SWA/about/

Publications/Documents/160/SolventVapourDegreasing_1989_PDF.pdf.

(NYSDEC, 2003) Environmental Compliance, Pollution Prevention and Self-Assessment Guide for Vehicle 

Maintenance Shops. New York State Department of Environmental Conservation. 2003.

(Pecht, 2003) Pecht, M. et al. Contamination of Electronic Assemblies. CRC Press LLC. 2003.

(PPRC, 1996a) Aqueous Cleaning Technology Review. Pacific Northwest Pollution Prevention Resource 

Center. 1996a. Available at: www.pprc.org/pubs/techreviews/aqueous/aqintro.html.

(PPRC, 1996b) No-Clean Technology Review. Pacific Northwest Pollution Prevention Resource Center. 

1996b. Available at: www.pprc.org/pubs/techreviews/noclean/nointro.html.

(TURI, 1995) Closed Loop Aqueous Cleaning. The Massachusetts Toxics Use Reduction Institute, 

University of Massachusetts Lowell. 1995.

(TURI, 1997) Guidebook of Part Cleaning Alternatives. The Massachusetts Toxics Use Reduction 

Institute, University of Massachusetts Lowell. 1997.