• What is the American Conference of Governmental Industrial Hygienists (ACGIH) recommended exposure limit for Tetrachloroethylene?
• What are the fire and explosion dangers associated with Tetrachloroethylene?
• Is Tetrachloroethylene stable when exposed to air, moisture, or heat?
• Are there any conditions to avoid when using Tetrachloroethylene?
• Does Tetrachloroethylene have an odour threshold (at what level can I smell it)?
• Is the odour of Tetrachloroethylene reliable as a warning property?
• How can I work with Tetrachloroethylene safely?
• What can be done to control hazardous conditions?

What is the American Conference of Governmental Industrial Hygienists (ACGIH) recommended exposure limit for Tetrachloroethylene?

TIME-WEIGHTED AVERAGE (TLV-TWA): 25 ppm - Carcinogenicity Designation A3

SHORT-TERM EXPOSURE LIMIT (TLV-STEL) : 100 ppm - Carcinogenicity Designation A3

TLV Basis - CRITICAL EFFECT(S): Irritation; CNS (Central Nervous System)

CARCINOGENICITY DESIGNATION A3 - Animal Carcinogen: Substance is carcinogenic in laboratory animals under conditions that are not considered relevant to worker exposure. Available human studies and evidence suggest that the substance is not likely to cause cancer in humans except under unusual or unlikely routes or levels of exposure. Worker exposure to an A3 carcinogen should be controlled to levels as low as reasonably achievable below the TLV.

BIOLOGICAL EXPOSURE INDICES (BEIs): The ACGIH has adopted a BEI for this chemical. BEIs provide an indication of worker exposure by measuring the chemical or its breakdown products in the body or by measuring biochemical changes resulting from exposure to the chemical. Consult the BEI documentation for further information.

NOTE: In many jurisdictions, exposure limits are similar to the ACGIH TLVs. Since the manner in which exposure limits are established, interpreted, and implemented can vary, obtain detailed information from the appropriate government agency in each jurisdiction.

What are the fire and explosion dangers associated with Tetrachloroethylene?

Tetrachloroethylene is not combustible. Closed containers may explode if exposed to excess heat for a sufficient period of time releasing large quantities of toxic gases or vapours (e.g. hydrogen chloride, phosgene and/or chlorine).

Is Tetrachloroethylene stable when exposed to air, moisture, or heat?

Tetrachloroethylene decomposes slowly in the presence of light (especially ultraviolet light) and air to form trichloroacetyl chloride and phosgene, if unstabilized. The unstabilized compound also hydrolyzes very slowly in the presence of water to form corrosive trichloroacetic acid and hydrochloric acid.

Are there any conditions to avoid when using Tetrachloroethylene?

Excessive heat, open flames, electrical arcs, welding arcs, hot surfaces or other high temperature sources, sunlight, moisture, depletion of stabilizers.

Does Tetrachloroethylene have an odour threshold (at what level can I smell it)?

A wide range of values have been reported; 2 to 71 ppm. Reliable values are 47 ppm (detection) and 71 ppm (recognition). Some people may not smell tetrachloroethylene at higher concentrations because they become accustomed to the odour.

Is the odour of Tetrachloroethylene reliable as a warning property?

POOR - odour threshold is about the same magnitude as the TLV; eye irritation threshold (101-216 ppm) exceeds the TLV; causes olfactory fatigue.

How can I work with Tetrachloroethylene safely?

This material is a VERY TOXIC liquid (SUSPECT CANCER HAZARD). Before handling, it is extremely important that engineering controls are operating and that protective equipment requirements and personal hygiene measures are being followed. People working with this chemical should be properly trained regarding its hazards and its safe use. Maintenance and emergency personnel should be advised of potential hazards.

If tetrachloroethylene is released, immediately evacuate the area. Immediately report leaks, spills or ventilation failures.

Unprotected persons should avoid all contact with this chemical including contaminated equipment.

Closed handling systems for processes involving this material should be used. If a closed handling system is not possible use in the smallest possible amounts in well-ventilated area, separate from the storage area. Avoid generating vapours or mists. Prevent the release of vapours/mist into workplace air.

Do not use near welding operations, flames or hot surfaces because of the risk of formation of toxic hydrogen chloride or phosgene. Do not perform any welding, cutting, soldering, drilling or other hot work on an empty vessel, container or piping until all liquid and vapours have been cleared. Follow the chemical supplier/manufacturer's advice regarding chacking and maintaining appropriate levels of stabilizers.

Do not use with incompatible materials such as strong acids (e.g. sulfuric acid) and strong bases (e.g. sodium hydroxide).

Stand upwind of all opening, pouring and mixing operations. To avoid splashing, carefully dispense into sturdy containers made of compatible materials. Prevent damage to containers. Label containers. Open containers on a stable surface. Keep containers closed when not in use.

Assume that empty containers contain residues which are hazardous.

Never return contaminated material to its original container. Keeping work areas clean is essential. Use work surfaces that can be easily decontaminated. Follow handling precautions on Material Safety Data Sheet. Have suitable emergency equipment for fires, spills and leaks readily available. Practice good housekeeping. Maintain handling equipment. Comply with applicable regulations.

What can be done to control hazardous conditions?

Engineering methods to control hazardous conditions are preferred. Methods include mechanical ventilation (dilution and local exhaust), process or personnel enclosure and control of process conditions. Administrative controls and personal protective equipment may also be required.

Because of the high potential hazard associated with this substance, stringent control measures such as enclosure or isolation may be necessary. A totally enclosed system with an associated purging system should be considered for unloading bulk material and sampling process liquids. To prevent the release of this material due to equipment failure, backup controls (e.g. double mechanical seals for process pumps) should be considered.

Use a ventilation system separate from other exhaust ventilation systems. Exhaust directly to the outside, taking necessary precautions for environmental protection.

Supply sufficient replacement air to make up for air removed by exhaust systems.

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Document last updated on February 19, 1999

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