Oxygen Depletion In Fires

[PRB]

We are supplying suppression systems in diesel generator enclosures for a client in the UK ,recently a question asked of us was why they needed a suppression system at all and if they made the enclosure virtually airtight would the fire not self extinguish when it uses up the oxygen!! .

We have had a couple of meetings and explained the level to which the oxygen would have to fall, the dangers of having a smouldering fire incipient fire waiting until some one enters an area and allows in a fresh supply of oxygen, in addition have asked them to consider the amount of damage that will be done by the fire before this occurs( diesel generator enclosure with approx 500 litres of fuel)

Would like to be able to show some data of how much oxygen a given size of fire would consume etc. or photo graphs of a diesel generator burnt out!!.

Have searched the internet cannot find anything any help you can provide would be appreciated

[John Webb]

If the air intake for the engine is inside the enclosure then the enclosure must be open to the air for the engine to work - so there is plenty of scope for continued burning once a fire starts.
Or if the air intake for the engine is outside the enclosure, there still may be openings for engine cooling etc which would allow air in.

In addition, the high-pressure side of the fuel injection system can spring a leak which effectively vapourises the diesel and makes ignition much more likely even with a small sorce of heat or flame - the leak can then act like a blowtorch.

Regarding the amount of oxygen needed, I'll look out some data I think I have lurking somewhere and post something - probably not till tomorrow pm.