diesel generator tank and hazardous area classification

[RKyleM]

Is there a point when a diesel fuel tank for a generator becomes so large that it becomes classified as a hazardous area required a special hazardous location rated tank? A few years back I worked on a project where I believe at 10,000 gallons, diesel becomes classified as "hazardous".

 

[dpc]

AFAIK, diesel fuel is not considered explosive in any quantity, at least by NFPA. We had a lot of arguments with engine-generators suppliers over the years, and always lost any argument that the fuel tanks, etc needed to be classified as hazardous locations. There was nothing that required this, at least 20 years ago. Even float switches inside fuel tanks did not have to be classified.

Or were you talking about some other type of hazard?

 

[RKyleM]

Thanks! I was just concerned that the quantity of diesel fuel itself would make it a hazardous location.

 

[dpc]

We have an NFPA Fire Code forum - you might want to post a question there.

 

[FreddyNurk]

I assume you're in the US with use of Gallons but we just went through this exercise for a diesel power station as we'd previously had a hazardous areas classification for the site when we were using HFO rather than diesel and were heating the HFO with a heat recovery steam system.

Post change to diesel, with no fuel heating, the only resultant hazardous areas that were found by the consultant we engaged were inside the ullage spaces on the bulk tanks. We also had a classification around our flammable goods storage cabinets, but that was to be expected.

Even the generator canopies were not considered to be a potentially explosive atmosphere. However, the consultant reminded us that just because the generator enclosures weren't hazardous, didn't mean that is the end of the risk, diesel, is of course, still combustible. What it meant was that (apart from any instrumentation within the ullage space, normally we don't have any) whilst we don't have to comply with hazardous area instrumentation and zoning, its still a good idea to eliminate potential sources of ignition where possible (turbos are one such example thats hard to deal with).

Our classification was in Australia, and is largely based on IECEx standards. I would assume that NFPA would be an appropriate reference, we have equivalent fuel storage standards here, though they don't always require hazardous area classification.

 

[waross]

You may have environmental containment issues, rather than explosive issues.

Bill
--------------------
"Why not the best?"
Jimmy Carter