Testing Fuel for Generators: Drilldown of NFPA 110 / ASTM 975 Rules
For those of you who just don’t like to read, or have only a moderate tolerance for reading codes and regulations, we have the done the dirty work for you.
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 13 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 13 tests included in the standard:
- Flash Point , Water and Sediment, Distillation, Viscosity, Ash Content, Sulfur, Copper Corrosion, Cetane Index, Cloud Point, Carbon Residue, Lubricity, Conductivity, Density
What are the Tests and Requirements
We breakdown the ASTM D975 tests into 2 groups:
- Test for Characteristics subject to Degradation. These should be annually tested.
- Tests for Characteristics unlikely to Change. May by excluded from annual by permission.
Now let’s look at additional tests, not included in the standard that may be recommended or required by the generator manufacturer. The reason they specify these tests is to ensure reliability. They do not want bad fuel impacting the best performance of the machine.
Finally Here is a Summary of Tests for Microbial Contamination.
Worksheet for Diesel Fuel Test Requirements
Here is a worksheet for determining the tests needed and calculating the cost. Most testing labs have package prices for common test groups, and that is how the Annual Low and Best are estimated. The local Authority Having Jurisdiction (AHJ) for Life Safety Code Compliance may require tests in addition to the Annual Low listed items.
