Oil be there

The Environment Agency will oversee policing of the pcb phase out, and users who break the deadline without speaking to the Agency face fines or even custodial sentences of up to two years.

PCBs were introduced in 1929 in order to prevent flammability problems with transformers. When added to the dielectric hydrocarbon oil, pcbs reduced, if not prevented, the likelihood of an electrical equipment fire.

With a gradual increase in the awareness of the environment and a growing number of adverse results from industrial plant, accidents, oil spills and widening uses of pesticides in the 1960s, pcbs came under scrutiny.

Observations showed that certain birds were reproducing with birth defects and fish fry was malformed. After biopsy, high levels of pcb were found in their tissue, while in fragile egg shells, usually associated with DDT, pcbs were also discovered. By the late 1970s pcbs were under full investigation. Removing all pcb from dielectric oil began.

Unfortunately, the removal or even direct screening of oil was not possible and could only be definitively determined by gas chromatography, an uncommon and expensive test at the time for the number of samples needing testing.

This changed when a team of scientists at General Electric and Dexsil Corporation, in conjunction with EPRI, USA came up with a simple and inexpensive field test kit which could be operated by non-technicians.

Clor-n-oil can recognise and determine the amount of chloride (a constituent of pcb) in a sample of oil. By comparing a sample against a colour chart, a level of less than 50 ppm (the legal limit) or over 50 ppm can be deduced. For those over the limit, a second gas chromatography analysis is required because, even though a high level of chloride may be present in the oil, it may be contaminated with harmless chlorine substances.

As a general rule, if you come across capacitors of the relevant age you should first inspect them. If they are leaking then get professional help. If they seem all right then note the manufacturer and serial number, then contact a specialist company like Phasetech which should be able to advise if they contain pcbs. "Equipment which dates from 1959 to 1978 almost certainly carries pcbs, so you've got to be suspicious," says Phasetech director Ken Virr. "Manufacturers started phasing them out rapidly after that so from late 1978 there's a fairly small chance that the equipment will contain pcbs. We can help because we have a database identifying models with the presence of pcbs."

Phasetech can also help with disposal. "First it has to be safely disconnected, then removed from site by a contractor which is Hazchem registered. Then it must be taken to a registered disposal and incinerator site," explains Virr.

Samples and equipment proven to be at a level above the legal limit must be fired at 1300oC in a special incinerator to ensure total destruction of the compound.

Though the end of the year is the cut off date, if a facility can show it has plans to replace all its switchgear in, say, a year's time then it may be able to get dispensation from the Environment Agency. In the meantime, the legislation offers contractors a good chance to offer equipment audits and disposal services.