Health effects of SF6 (again)

[omara]

Thanks to all who provided answers to my original question. Unfortunately, I apparently was not precise or clear enough about my requirements.

I'm looking for information the effects of the compounds resulting from arcing in SF6 on the health of the technicians working to repair the switchgear after the fault. Note that in some cases the integrity of the switchgear has already been compromised by the fault and these compounds are already in the switchgear hall environment.

What are the guidelines for working in this environment? What safeguards should be taken by the people working there? Are there any short- or long-term health problems that may be expected?

I'll be grateful for pointers to any site that deals with these issues. All I've found so far are mention that the compounds are dangerous and the effects of SF6 as a greenhouse gas.

Thanks again.

 

[electricpete]

If your company is a Doble client, as your client rep. There have been a few articles on this subject in the Doble Proceedings.

 

[busbar]

http://www.actiinc.com/

in Sacrameto, CA may have some information.

 

[jbartos]

Suggestion: It appears that you have a great safety concern about your technicians working with installed SF6. In this case any regulation, codes, and local/state/federal laws should be adhered to. Visit

http://www.osha.gov

http://www.access.gpo.gov/nara/cfr/cfr-table-search.html

http://www.nfpa.org

etc. for more info
Head on start from OSHA:
January 30, 1989
MEMORANDUM FOR: REGIONAL-ADMINISTRATORS
THRU: LEO CAREY
Director
Office of Field Programs
FROM: EDWARD J. BAIER
Director
Directorate of Technical Support
SUBJECT: Safety Hazard Information Bulletin on Work Practices Employed by the Electric Utilities Industry Regarding Sulphur Hexaflouride Gas-Insulated Circuit Breakers

An inquiry was forwarded to this office by the OSHA New York Regional Office regarding a possible safety hazard associated with sulphur hexaflouride (SF(6)) circuit breakers used by electric utilities in high-voltage transmission and distribution applications. The Edison Electric Institute (EEI) was most helpful in providing information necessary for this bulletin.

In response to the above inquiry, we conducted a series of investigations including discussions with utility industry representatives and an on-site visit to a utility substation to determine any potential existing hazards. According to the EEI, member companies have been using SF(6) gas-insulated circuit breakers for 20 years with associated maintenance hazards being well-known within the industry. The chief safety hazard is the potential exposure of maintenance employees to residual toxic by-products of SF(6) breakdowns that occur after the gas is exposed to a series of arcings. In most cases, the by-products (when present) may total a few grams. EEI estimates that SF(6) equipment is used in general about 80 percent outdoors and above ground, 15 percent indoors and 5 percent below ground. Attached is one company's substation maintenance bulletin containing work practices for SF(6) gas-insulated equipment.

During the on-site local substation visit, Virginia Power Company personnel demonstrated maintenance procedures for a 230 kilovolt Westinghouse circuit breaker which was undergoing door seal replacement due to a leak. The observed Westinghouse unit consists of three interrupters and housings sharing a common gas system. (See attached photograph.) Low pressure, 45 psig SF(6) surrounds the interrupter and acts as an insulator. High pressure (approximately 270 psi) SF(6) is used to extinguish arcing during an interruption cycle. After the gas was evacuated from the breakers and deposited in a gas reclaiming system, and prior to replacing the door seals, Virginia Power personnel demonstrated what they would do if the presence of SF(6) by-products had been found. The Virginia Power personnel wore protective clothing with air purifying respirators and used vacuum cleaners with high-efficiency particulate air (HEPA) filters to demonstrate the manner in which toxic residue would be removed if it were present.

Also attached is a response prepared by EEI to OSHA questions regarding SF(6) equipment. The attachment provides, among other things, information on the design and potential failure of equipment and detection of gas leaks. It also addresses precautions that must be taken if equipment is located in a confined space.

Please distribute this bulletin to Area Offices, State Plan States and Consultation Projects.