• ISSN: 1195-5228
  • Issued: December 2004
  • Revised: March 1, 2014
  • Content last reviewed: March 2014

Hazard Summary

A 40 year-old diver was critically injured when his diving suit over-inflated while working inside an opening of a sewer pipe.

The victim was vacuuming the inside of a flooded storm sewer when his suit unexpectedly began to inflate causing him to blow up against the roof of the pipe. The victim was wearing a dry suit and was using a surface-supplied diving helmet.

The investigation has shown that the diving harness interfered with the operation of the diver's suit. Specifically, the design of the particular harness inadvertently activated the suit inflation valve when the diver crouched in the sewer pipe, causing an uncontrolled blow-up and trapping him against the top of the sewer pipe. The harness is a type that crossed across the chest. When the diver crouched inside the pipe the harness strap slid over the inflator of his dry suit causing an uncontrolled over-inflation. The inflator valve on this suit was found to have a high profile activator that rises above the protective shroud of the valve. As the suit began to inflate the diver could not raise his arm to discharge the overpressure through the exhaust valve.

Hazard Location

This hazard may occur whenever a cross-chest type of diving harness is worn. This type of harness must be avoided if there is a possibility that a harness strap can accidentally activate the suit inflator valve.

Photo of a cross-chest type diving harness Detailed photo of a cross-chest type diving harness


  • Ensure during pre-dive checks that suit inflator valve cannot be activated by harness straps.
  • Relocate suit inflation valve to an area on the suit that will not allow the diving harness straps to interfere with the suit inflation valve.

Legal Requirements

The Occupational Health and Safety Act describes responsibilities that constructors, employers, and supervisors have in protecting the health and safety of workers, (refer to sections 25 -28 of the Act). Clause 16(3)(d) of the Regulation for Diving Operations (O. Reg. 629/94) requires the diver and the diving supervisor to ensure that the diver is equipped with a five-point diving harness that meets the requirements of Clause 8.3.5 of CSA Standard Z275.2-11, "Occupational Safety Code for Diving Operations".

For further information or assistance, please call the Ministry of Labour, Training and Skills Development Health & Safety Contact Centre, or contact the Industrial Accident Prevention Association, the Infrastructure Health & Safety Association or other safe workplace associations.

This Ministry of Labour, Training and Skills Development Alert has no legal effect and does not constitute and is not a substitute for legal advice. If you require specific assistance with respect to the interpretation of a legislative provision and its potential application to you please contact your legal counsel.

Remember that while complying with occupational health and safety laws, you are also required to comply with applicable environmental laws.

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This resource does not replace the Occupational Health and Safety Act (OHSA) and its regulations and should not be used as or considered legal advice. Health and safety inspectors apply and enforce these laws based on the facts they find in the workplace.