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Outdoor Diesel Fuel Storage adjacent to building.

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EEJaime

Electrical
Jan 14, 2004
536
Gentlemen,

I have a peculiar condition at a new project site that I am trying to design. The Architects are driving me insane as usual. Additionally, we have a mechanical engineer from a competing firm and a code consultant that I feel is being overly conservative, (by definition I believe).

What I have is two 1500kW generator sets each sitting on a 1000 gallon diesel, skid mounted fuel tank. These units sit outdoors in a recessed enclosure which will essentially be a concrete tub 45' square.

In addition to this we have a condition where there will be a temporary passenger connector tunnel, (corridor), built about 30' above the generator yard to connect a new passenger terminal concourse with the existing airport terminal structure. This will be in place for a maximum of 14 months.

My reading of NFPA codes leads me to the conclusion that the design is well within applicable code requirements.

Namely NFPA 37, 6.3.3 "FUEL TANKS OUTDOORS(ABOVEGROUND OR UNDERGROUND) OR BENEATH A STRUCTURE. Fuel tanks located outside, either aboveground or underground, or beneath a structure, shall comply with provisions of NFPA 30, Flammable and Combustible Liquids Code."

And NFPA 31 INSTALLATION AND USE OF STATIONARY COMBUSTION ENGINES AND GAS TURBINES, 7.9.3 "A tank or tanks whose capacity exceeds 660 gallons shall be installed in accordance with all applicable requirements of NFPA 30, Flammable and Combustible Liquids Code."

And finally NFPA 30, 15.4-"Outdoor Storage Adjacent to a Building." as well as Tables 22.4.1.1(a) and T22.4.1.1(b) allow this installation as long as:
1) The adjacent building has a 2 hr rating
2) The adjacent building has no openings at grade or above grade that are within 10 ft horizontally of the storage.
3) The adjacent building wall has no openings directly above the storage.
4) The adjacent building has no openings below grade withing 50ft horizontally of the storage.

And from the tables for fuel quantities between 660 and 12000 gallons we need 5' "From Nearest side of any public way or from Narest Important building on the same property. This distance is then halved for a protected above ground tank.

I feel that we meet all requirements for this installation.

I hope I've provided sufficient information for some feedback.
Thank you and regards,
EEJaime
 
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The only item in the analysis I disagree with is the application of the requirements of NFPA 30, Chapter 15. It's not applicable because you're not dealing with containers, portable tanks or IBCs. All of your requirements are set forth in NFPA 30, Chapter 22 and based on the application of Tables 22.4.1.1 (a) and (b), you're conclusion is correct - a minimum separation distance of 5 feet is required from the building.
 
Stookey,

Thank you for the response. The skid mounted tank is in fact bolted down with seismic vibration isolators, but I thought being a piece of replaceable equipment it would still be considered a portable tank. If that is not the case, then which part of NFPA 30 would govern the location of the sub-base tank?

Regards,

EEJaime
 
Chapter 22 is applicable because your sub base tank is a stationary aboveground storage tank (AST). NFPA 30 has no specific requirements for generator sub base tanks. In fact the only difference between a UL 142 conventional AST and a sub base AST is UL requires that the sub base tank be rated for a certain weight plus a design factor of 1.5. Side by side, a UL 142 sub base tank may look different if compared to a UL 142 horizontal circular tank but they all are required to have the same features and tank nozzle openings.
 
Thank you very much. I appreciate your assistance.

Regards,

EEJaime
 
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