Many drycleaners are completely unaware of the potential problems if perchloroethylene-contaminated air is drawn into the burner of a gas fired dryer.

One cleaner whose perc machine had broken down at the start of drying even asked if the load could be transferred and dried in the tumbler.

If perc vapour is exposed to a naked flame, it decomposes to form hydrochloric acid and phosgene gas, which are highly acidic and toxic. Formation of hydrochloric acid in a tumbler can result in chemical damage to the textiles and, over a period of time, cause catastrophic corrosion damage to the burner and other components such as the cage.

Although modern drycleaning machines use solvent very efficiently, vapour concentrations in the vicinity of the machine to can, at times, exceed 50ppm during unloading operations. This is quite sufficient to cause problems with gas-fired tumble dryers. If there is a smell of perc in the vicinity of a dryer while it is operating, the risk of damage is substantially reduced if the dryer is stopped until such time as the air has cleared.

The long term solution is to install ventilation to ensure that air that may be contaminated with solvent vapour is drawn away from the dryers.