NCWM Premium Fuel Guidelines
The following are the five performance properties that comprise the National Conference on Weights and Measures (NCWM) Premium Diesel Fuel Standards. As of 2004, a Fuel marketer must meet all of these standards in order to be able to advertise a fuel as “Premium Diesel” in states that adopt the NCWM standards.
Energy (Btu) Content: The fuel must have at least 138,700 Btu, as measured by ASTM D-240
Cetane Number: The fuel must have a Cetane number of at least 47, as measured by ASTM D-613.
Lubricity: A maximum wear scar diameter of 520 microns as determined by ASTM D 6079. If an enforcement jurisdiction?s single test of more than 560 microns is determined, a second test shall be conducted. If the average of the two tests is more than 560 microns, the sample does not conform to the requirements of this part.
Low Temperature Operability: A cold flow performance measurement which meets the ASTM D 975 tenth percentile minimum ambient air temperature charts and maps by either ASTM Standard Test Method D 2500 (Cloud Point) or ASTM Standard Test Method D 4539 (Low Temperature Flow Test, LTFT). Low temperature operability is only applicable October 1 ‑ March 31 of each year.
Thermal Stability: The fuel must get at least an 80% reflectance as determined by ASTM Standard Test Method D 6468 (180 minutes, 150 ?C).