An Experimental Study of Fire Hazards in Enriched Oxygen Hyperbaric Environments

The Health & Safety Laboratory (HSL) has a large (200m³) fire-resistant hyperbaric test facility at its site in Buxton, Derbyshire. This facility has previously been used to study hyperbaric fires in support of HSE's fire safety guidance for the Work In Compressed Air Regulations (1996).

Test work has been carried out to examine the effects of increased oxygen concentration, such as may occur in a lock during oxygen decompression. Relatively low increases (25% oxygen by volume) were used, reproducing conditions where an “alarm” condition might just be given. Test fires were carried out using a single, clothed mannikin.

The tests showed that this level of oxygen volume concentration gave a measurable increase in the severity of a fire, which was greater than that resulting from a similar level of oxygen partial pressure but obtained by raising the chamber pressure using air.

The actual consequences of a fire during a decompression stop with 25% oxygen due to leakage, were not significantly worse than the consequences of a fire in the chamber earlier in the decompression process, with compressed air only but at higher pressures. Thus the fire precautions which are appropriate for the higher working pressure should also be appropriate for a lower pressure decompression stop, even if leakage raises the oxygen concentration slightly. However, further increases in oxygen concentration would raise the fire risk, so that detection of higher levels remains important.

• INTRODUCTION

• OXYGEN IN HYPERBARIC FIRES

• EXPERIMENTAL FACILTY

• PREVIOUS RESULTS

• OXYGEN TESTS

• RESULTS FROM TESTS

• CONCLUSIONS

• REFERENCES