I work on a large biotech site with multiple buildings including labs / plant buildings / manufacturing buildings etc.  Many of these have O2 monitoring in place to identify oxygen depletion as we use a lot of liquid nitrogen.  There are discrepancies across these alarm systems as to which value for Oxygen they alarm at, and hence the area is evacuated.  These range from 18%-19.5% (atmospheric concentration is 20.95%).

Does anyone know what the HSE's recommendations for O2 depletion alarm settings are? I am struggling to find anything concerete.

Thanks

...beaten to it by UncleFester!...

Have a look at the HSE Research Report 973. 'Review of alarm setting for toxic gas and oxygen detectors'.

There's a lot of waffle but some good snippets of industry best practice is quoted within.

Jamie 

Edited by user 29 March 2018 09:47:03(UTC)  | Reason: Beaten to the post!

We have a hypoxic fire prevention system that runs around 16.4 to 17% O2 with the alarm set at 15%

We restrict the exposure hours to 4hrs - and allow access for rescue down to 13% in extremis

There isn't anything set in law...however part of the C&G training syllabus gives O2 Min 19.5% - Max 23.5%..

:)