Standby Generator Fuel Testing

The National Fire Protection Agency’s “Standard for Emergency and Standby Power Systems” (NFPA 110) states that:

Standby Generator Fuel Testing“8.3.7 A fuel quality test shall be performed at least annually using applicable ASTM standards or the manufacturer’s recommendations.”

“A.8.3.7 All testing should be performed using ASTM-approved test methods such as, but not limited to…”

  • The NFPA 110 Standard provides guidelines for the maintenance of standby power units used in nursing homes and hospitals, including annual testing for fuel quality using ASTM methods.
  • Examples of ASTM tests are given, but the NFPA 110 Standard does not state specifically what tests are to be performed.
  • Iowa Central Fuel Testing Laboratory can work with you and your local inspector to determine which ASTM method(s) will best suit your needs.

How Will We Report Your Results?

We will provide you with a Certificate of Analysis showing all of the required tests and limits for diesel (ASTM D975) or gasoline (ASTM D4814).  The tests you ordered will have the “Results” column filled in with the result value from the test.

The ASTM Standards provide detailed requirements for diesel and gasoline fuel tests including specified minimum or maximum values allowed. The Standards also describe tests that may provide additional information but do not have a specified limit.

For ASTM tests with a specified limit, your Certificate of Analysis will show “Pass” or “Fail” in the Pass/Fail column as appropriate.

For ASTM tests without a specified limit, your Certificate of Analysis will show “Report” in the Pass/Fail column to indicate that the reported value does not have a specified limit in the respective ASTM Standard.

Diesel Generator Tests

The ASTM D2709 Water & Sediment Test is a centrifuge test that will determine the amount of free water and debris present in your fuel sample.  This test has a required maximum value in the ASTM D975 Standard for diesel fuel and will come with a Pass or Fail designation.

The ASTM D6304 KF Moisture Test is a much more sensitive test that will determine the amount of water entrained within the fuel.  Excess water in the fuel can reduce operating efficiency, potentially plug filters in the winter time, and provide a more favorable environment for microbial growth.  This test is not part of the ASTM D975 Standard requirements and will have “Report” instead of a pass or fail. 

The ASTM D6974 Microbial Count Test gives an approximation for the bacterial and mycological (molds and fungi) content of the fuel.  Excess microbial activity can cause fuel degradation over time and contribute to filter plugging.  This test is not part of the ASTM D975 Standard requirements and will have “Report” instead of a pass or fail.  The D6304 KF Moisture content along with the Microbial content can provide a very useful snapshot of fuel quality.

The ASTM D2500 Cloud Point test will report the cloud point of the fuel in degrees Celsius.  This is important if the bulk storage of fuel is outside or otherwise subjected to cold temperatures.  The cloud point of the fuel will give an indication of how cold it can get before it begins to gel.  The Cloud Point test is required for the ASTM D975 Standard but, due to regional differences, no minimum value is given.  Please contact us or your fuel supplier to help you determine if your cloud point is sufficient for your needs.

Diesel Generator Test Packages

Gasoline Generator Tests

The ASTM D381 Gum Content Test will measure the amount of gum residues present in the fuel.  Gums are varnish-like oxidation products that can cause sticking and plugging of moving fuel components and can be an indication that the fuel is becoming old.  The ASTM D4814 Standard for automotive gasoline (up to 15 % ethanol) lists a required maximum value for gum content, and this result will have a Pass or Fail designation. 

The ASTM D6304 KF Moisture Test will determine the amount of water entrained within the fuel.  Excess water in the fuel can reduce operating efficiency, and when combined with ethanol, can cause phase separation when in excess.  Phase separation will cause the water and ethanol to separate out from the gasoline, ending up at the bottom of the storage tank.  If this mixture is delivered to the generator, immediate shutdown will occur.  This test is not a requirement under ASTM D4814 and will have “Report” instead of pass or fail.

The ASTM D4815 Ethanol Content Test will determine the amount of ethanol in the gasoline for blends containing up to 15 % ethanol.  This test, along with the KF Moisture test, is very useful in helping to determine if excess water causing phase separation has, or is about to, occur.

Gasoline Generator Test Packages

How do I order tests?

Ordering tests is easy! Just call 877-737-4853 or email fuels@iowafuellab.com to place an order. You can also click on "Testing Services" then "Testing Service Packages" to view all available packages including our Standy Generator Fuel Testing Packages. You can also click the buttons below to view either just Gasoline or Diesel Test Packages.

Once you place an order, we will send a shipping kit (or kits depending on how many generator units you have). Once you receive the kit, fill out the Chain of Custody form, fill the sample bottle, package securely in the box and use the enclosed return shipping label to return the sample to us via UPS. Once we receive the sample, testing usually takes 3-5 business days and we will email your final Certificate of Analysis. If everything is satisfactory and no further testing is needed, we will invoice you.