Auto Blow Downs on Gas Detection
Auto Blow Downs on Gas Detection
(OP)
Is anyone aware of a code and/or published guideline that requires an auto-blowdown of a natural gas facility when a gas detection event is triggered? We often do this at 20 ppmv or 40% LEL but is this a code requirement or just common practice. The plant is 24 hour attended and the owner is asking us to remove the auto-blowdown feature and let the board operator make the decision. Operating pressures range from atmospheric right up to 1400 Psig with sour gas. Any thoughts?





RE: Auto Blow Downs on Gas Detection
One possible way to reconfigure the system is to allow the operators for a certain amount of buffer time, upon initiation of an ESD. One of the plants where I worked (but handling gas with no H2S) has had an ESD system where automatic blowdown was delayed for 90 seconds - a relatively sufficient time for operators to investigate if gas/fire detection was false, or not. This was happening if only one of the detectors has got activated. If two, or more detectors, have got activated simultaneously, blowdown was instantaneous.
http://antwrp.gsfc.nasa.gov/apod/astropix.html
RE: Auto Blow Downs on Gas Detection
RE: Auto Blow Downs on Gas Detection
So like the other posters, I would be somewhere in between. A single detector no-auto blowdown, two or more - automatic as if it's gone horribly wrong you want to take the action out of the hands of the overworked controller....
My motto: Learn something new every day
Also: There's usually a good reason why everyone does it that way