Ammonia leak during a power failure

[RANGER1]

Nanuuk,
Just a few comments as each country, region have different standards.
Also we do not know what you have.
Can suggest ammonia detection in plant room with mechanical ventilation rated or designed for this duty.
It can be used for shunt trip of plant to avoid explosive atmosphere, which can be set at a very low level so you know of possible developing problem & so it's more human friendly.
Pre-alarm could be before shunt trip.
Constant ventilation fans can have detector in it's or their air stream.
Also all areas of plant can also have ammonia alarms, roof spaces which can also have ventilation, vessels & pumps etc.
Bunding around vessels that hold ammonia & water drain areas have to be addressed so the whole community & environment does not get affected.
Maybe you need to get an expert in to asses, as that's a paper trail as well.
I'm sure it's standard for you to also check relief valves, high pressure cut outs of compressors (set at least 10% below relief settings) pipework & vessel inspections etc
Relief vent lines also are important for when plant is on or off, where do they go, what & who will it affect if one relieves.
Some are put through a scrubber or water tank.
Some leaks depending where they are, can only be isolated & wait till it leaks out, like a condenser coil or similar.
Your own staff also have to have correct training & equipment up to date.

http://www.awsacanada.com/AWSA06/ASP.html see downloads

http://www.cdc.gov/niosh/docs/81-123/pdfs/0028-rev.pdf

http://www.csb.gov/file.aspx?DocumentId=682


Liquid ammonia pumps with shaft seal also to be avoided as major source of leak.