Fire hazardous envelopes (6-12m)

[jdhariwal]

Dear all,

I was wondering if someone could impart a bit of advice.

I am developing fire hazardous zones and have been using api 2218

It gives some guidance that the zone can extend 6-12m

How does one differentiate where in that range does that zone extend? When should I use 6 or 12 m?

Is there any recommended text or guidance?

Many thanks

Jess

[safetyuser]

Dear all,
How does one differentiate where in that range does that zone extend? When should I use 6 or 12 m?
Is there any recommended text or guidance?
Jess

Dear Jess, I suppose you are the specialist in the field and your expert judgment is the first guidance...
Secondly: at the end your Client will give an advise on your selection.

Then: is 12m too much impacting on your design? if not then the most cautious assumption can be selected.

And more, the 50:50 option is the "total uncertainty rule" in the sense that the middle range maybe the last chance when you have no idea on how to support your design.

Finally, a Quantitative Fire Risk analysis may help you in making decision but this is a rather time-consuming activity and you might be suprised
if the range of FPZ would result in larger needs than 12 metres.