Testing Diesel Fuel for Generators - Drilldown of NFPA 110 Rules

NFPA 110 “Standard for Emergency and Standby Power Systems” is the standard for people who own and operate buildings with emergency generators.  It’s the starting point of what a building owner should consider as good practice, and may go further toward a legal requirement since it is referenced in building codes.

ASTM gets drawn into this through NFPA 110 Part 8.3.7: A fuel quality test shall be performed at least annually using appropriate ASTM standards.

That is simple enough, but gets a bit more complicated by the detail in the Appendix sections of the standard.  Here we will review each concept

Appendix: A8.3.7 for “Fuel Quality Test”

Fuel Testing: “Limited fuel quality testing performed annually using appropriate ASTM test methods is recommended as a means to determine that existing fuel inventories are suitable for continued long term storage.  Special attention should be paid to sampling the bottom of the storage tank to verify that the stored fuel is as clean and dry as practicable and that water, sediment, or microbial growth on the tank bottom is minimized.  ASTM D975 Standard Specification for Diesel Fuel Oils, contains test methods for existing diesel fuel.”

How do we figure out the “appropriate” ASTM standard, and what is “limited” testing to be performed annually.  The problem is that ASTM D975 Standard Specification of Diesel Fuel Oils covers 7 grades of fuel, 66 ASTM reference standards, and 12 detailed test requirements.

And the standard is designed for evaluation of newly refined fuels, not for evaluating fuels in long term storage.  So there will be various opinions amongst generator manufacturers, testing labs, and other experts as to exactly what is required.

Here is a summary of the 12 tests included in the standard:

Fuel Testing for Long Term Storage

Testing of fuel for long term storage is not directly addressed by D975. Fuels stored for more than six months are subject to aging degradation – oxidative products, condensation buildup, and microbiological growth. Here is a summary of the tests typically recommended:

Cetane Index, Cloud Point, Density, Distillation, Flash Point, Sediment and water, Sulfur Content, Oxidative Stability, Particle Contamination