This is sort of a Section 90.2 issue; "This Code is not intended as a design specification or an instruction manual for untrained persons." That is, you won't necessarily find a detailed Code answer to every question. That said, the real consideration is to determine how the Fuel Calibration Hangar is properly classified. To the extent that conditions mirror Section 513.3, you can document [Section 500.4] the location classifications per Section 513.3. Otherwise, you will need to reference something like NFPA 497 or 30. Once that is done then proceed as with you would otherwise.