Contamination of divers air supply

An incident occurred on a DSV where a diver’s air supply became contaminated with fumes from an overheated electrical compound. This caused the diver to fall unconscious in the water. Although he was recovered to the surface and resuscitated, the incident could have been fatal.

The investigation revealed that the diver’s primary air supply was taken directly from a high pressure (HP) bank which was being continually charged during the diving operations. The HP compressor used to charge the supply was fitted with an electric dehumidifier which had been left switched on for over 48 hours. The electrical components in the dehumidifier subsequently overheated and discharged noxious gas, which contaminated the supply.

The contractor has carried out the following actions:

  • diving air supply on-line to the diver is no longer supplied from a HP bank being charged
  • all HP supplies are analysed before being put on-line
  • the electrical power supply to the HP compressor dehumidifier has been fitted with a time switch to prevent it being accidentally left on for extended periods and overheating