Self rescuer units 'can catch fire'
Published: 18 June, 2012
nits can catch fire if start-up procedures are not followed.
The HSE warning relates to MSA SavOx units, which have been sold for over a decade and are widely used in mines and civil tunnelling.
The unit contains a chemical canister and when the unit is worn the user’s breathing triggers a chemical reaction which produces oxygen. A by-product of this chemical reaction is heat.
The SavOx units are fitted with a starter mechanism which is designed to provide immediate oxygen and boost the start up reaction when the units are operated in low temperatures. This starter mechanism should be initiated by stretching the flexible breathing tube prior to inserting the mouthpiece.
Following a large emission of gas in a 2000m long coal mine development (tunnel) workers donned their SavOx oxygen rescuers to evacuate the affected area.
Burnt breathing bag and scorched KO2 chemical canister.
On reaching fresh air they removed their rescuers and laid them on the floor. Approximately 10 minutes later one of the team picked up one of the used rescuers by the mouthpiece and a ‘popping’ sound was heard. The rescuer began smoking from around the exhale valve and then burst into flames. The flames were quickly extinguished and no persons were injured.
It appears that the wearer had not triggered the starter when he put on the rescuer and when the used rescuer was picked up by the breathing tube the starter was activated. The unit was already hot and this supply of additional oxygen led to the fire.
The incident does not appear to be an individual manufacturing defect and further investigation is being undertaken.
The HSE is encouraging companies to ensure that all users of Savox units are trained and have been assessed to be competent in the use of the unit and, in particular, understand the importance of following the correct start up procedure.
For further information contact the Specialised Industries Division, HM Inspectorate of Mines, on Tel: +44 (0) 114 291 2390, or click here.