Bruce,
The vent is a 1" line, between 2 to 3 mts, from an inert gas generator unit, a packaged equipment. The unit uses fuel gas (MW 21). The vent gas stream is a varying mixture of fuel gas vapour and nitrogen with 3% oxygen. The equipment is on an FPO (floating production and off loading) topside.
The BS EN 12874 groups arresters according to the gas group. Each of the gas groups has a corresponding MESG (maximum experimental safe gap, the gap between the plates of the arrester) under which an arrester is type tested under a series of deflagration and detonation tests.
The vendor selects the stream as of IIA.
The standard defines IIA as propane of purity by vol% >= 95, Gas in air vol% = 4.2.
Sajit Viswan
Piping Materials Engineer
Technip Abu Dhabi
UAE
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Received on Thu Feb 08 02:01:00 2007
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