Archive for January, 2019


I thank Michelle Hilger for inspiring me to write about today’s topic – the disconnect between the guidance NFPA provides about emergency generator fuel supplies and reality. Michelle chairs the Emergency Generating Systems Association’s (EGSA’s) Fuel: Fact or Fiction Working Group.

NFPA (National Fire Prevention Association) Standards Related to Fuel Storage

The NFPA provides fuel condition monitoring guidance in two documents:

  • NFPA 110, Standard for Emergency and Standby Power Systems; and
  • NFPA 25, Standard for the Inspection, Testing, and Maintenance of Water-Based Fire Protection Systems.

During her brief, presented to ASTM D02.14’s Fuel Microbiology Working Group in June 2018, Michelle reported that NFPA 110 prescribes the following:

  • Chapter 8.3.7 -A fuel quality test shall be performed at least annually using appropriate ASTM standards or manufacturer’s recommendation (Revision for 2019 Edition)

She also reported similar language in NFPA 25:

  • Chapter –Diesel fuel shall be tested for degradation no less than annually.
  • Chapter –Fuel degradation testing shall comply with ASTM D975, Standard Specification for Diesel Fuel Oils

Ensuring that fuel in emergency system storage tanks is fit for purpose is laudable, but insufficient.

What’s the Problem?

Some years ago, a maintenance engineer at a major resort hotel estimated that if there was a power outage and the hotel’s generators did not start and operate reliably, it would cost the hotel’s owners more than $2 million for each minute the facility was without power. Now ponder what the cost impact might be – in dollars and possibly lives – if a hospital’s emergency power system did not operate when needed (you can find some statistics if you research the impacts of recent hurricane disasters in Florida, Louisiana, Texas, and other southern states.

There is no debate that it is imperative to check the condition of stored fuel periodically. However, just determining that the bulk fuel meets ASTM D975 Table 1 specifications provides no information about the fuel system’s condition.

For several years – beginning with efforts to have proposed revisions incorporated into NFPA 110’s 2016 edition – the ESGA has been trying to educate NFPA stakeholders and broaden the scope of prescribed fuel system inspections.

For those of you who are new to this blog series, I invite you to start with my November 2016 post and read the entire series. This will help you to understand the rationale for ESGA’s efforts. In today’s post, I’ll just highlight two of the most important issues.

Fuel Quality Testing is a Snapshot

ASTM product fuel specifications were developed and are frequently revised to ensure that entities supplying and entities purchasing product have a common understanding of the criteria by which that product is defined as being fit for purpose. ASTM (and other consensus standard bodies – for example the International Standards Organization (ISO)) standards list parameters, test methods and pass/fail criteria that stakeholders can use to ensure that the product is fit-for-use at the time of sampling. Specification test results do not predict the product’s future condition. Under optimal storage conditions, emergency diesel generator fuel can be stored for prolonged periods (years). However, optimal storage isn’t always possible.

Fuel Versus Fuel System

Although my personal focus is microbial contamination and biodeterioration, in ASTM D6469 Guide for Microbial Contamination in Fuels and Fuel Systems I openly acknowledge that one major challenge to biodeterioration diagnosis is the number of symptoms that biodeterioration shares with non-biological (abiotic) fuel and fuel deterioration processes. Fuel can accumulate water and particulate matter. It can also become corrosive. Most engines can operate – at least for some time – using degraded fuel, but there’s a cost. CRC Report 667 Diesel Fuel Storage and Handling Guide (Coordinating Research Council, Alpharetta, GA, 2014) summarizes the most common fuel deterioration symptoms, their causes, and best practices for preventing problems. Two Energy Institute (EI) guidance documents are scheduled for publication in 2019:

  • Guidelines for the investigation of the microbial content of liquid fuels and for the implementation of avoidance and remedial strategies; and
  • Guidelines on detecting, controlling, and mitigating microbial growth in oils and fuels used at power generation facilities.

In the U.S., the Diesel Fuel Oil Group (DFOG) – a consortium of nuclear power industry professionals responsible for diesel fuel oil storage at power generation facilities – in collaboration with the Institute of Nuclear Power Operations (INPO) – has recently published:

Practice Guide: Management of diesel fuel quality for emergency diesel generators at nuclear power stations.

The publications coming from CRC, DFOG & INPO, and EI reflect the stakeholder community’s growing recognition of fuel system condition monitoring in addition to fuel quality testing.

What Needs to Happen

For many owner and operators, NFPA standards don’t just dictate minimum condition monitoring actions, they dictate all actions. If it isn’t prescribed in NFPA 110, then emergency generator system owners typically choose to avoid the incremental expense of fuel system condition monitoring. Historically, emergency standby diesel power generation system failures have cost tens of millions of dollars and countless lives.

EGSA has proposed new language for inclusion in NFPA 110 Chapter 8:

8.3.7 –Diesel fuel maintenance and testing shall begin the day of installation and first fill in order to establish a benchmark guideline for future comparison. Diesel fuel shall be tested for degradation no less than twice annually, with a minimum of six months between testing. All testing shall be performed using ASTM approved test methods and meet engine manufacturer requirements. Fuel testing shall be performed on all diesel fuel sources of EPSS. –Tests shall include at minimum, Microbial Contamination per guidelines referenced under ASTM D6469, Free Water and Sediment (ASTM D2709), and Biodiesel Concentration (ASTM D7371). Similar, modified, and proven methods recognized under ASTM shall be accepted. For acceptable values consult with the engine manufacturer and most current ASTM test documents -ASTM D975-18, and the Appendix X3.1.3 of ASTM D975-18, Standard Specification for Diesel Fuel Oils. –For diesel fuel stored consecutively for 12 months or longer, a diesel fuel stability test shall be performed annually. PetroOxy (ASTM D7545) is the accepted ASTM test method for S15 diesel fuels containing up to a biodiesel blend of 5% and less. Additional methods may be acceptable, refer to most current ASTM test documents -ASTM D975-18, and the Appendix X3.1.3 of ASTM D975-18, Standard Specification for Diesel Fuel Oils. –Any additional testing requirements shall be determined by equipment manufacturer, government regulations, recent test results, and geographical region. Refer to the most current NFPA 110 Annex A, ASTM D975 Appendix, and the CRC Report No. 667, Diesel Fuel Storage and Handling Guide for detailed testing and descriptions. –If diesel fuel is found to be outside of acceptable range in the testing listed in, the fuel shall be remediated to bring back to the required fuel quality for long-term storage specified under ASTM. Remediation may be in the form of fuel additives, polishing, tank cleaning, or diesel fuel replacement, and will be dependent of the test results received.

It’s time for NFPA to adopt these proposed changes and thereby substantially reduce the risk of emergency generators failing to operate when needed. Similar changes should also be made to NFPA 25.

As always, please share your thoughts with me by writing to For more information about EGSA’s activities, contact Michelle Hilger at


  • Consulting Services
  • Condition Monitoring
  • Microbial Audits
  • Training and Education
  • Biocide Market Opportunity Analysis
  • Antimicrobial Pesticide Selection