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During the ice storm in North Carolina we saw a problem develop with microbial contamination in diesel fuel that resulted in unsatisfactory performance from some emergency generators in the Greensboro market. This was not wide spread and most markets were not affected, however, the problem can happen anywhere.

Fuel contamination can appear in many forms. Chemical contamination, particulate contamination, water contamination, and microbial contamination are the most common.

Chemical contamination is the most difficult to detect because so many materials mix with diesel fuel. In years past it was not uncommon for a vender to mix non-fuel items with engine fuels to both dispose of the unneeded material and give it value by selling it as diesel fuel. Old transformer cooling oil was commonly disposed of in this fashion until the EPA's clamp down on PCBs brought this practice to a halt.

Still it would not be unheard of to find adulterated fuels still available. Unfortunately, Greensboro experienced this problem in August of 2000 with one of their portables. We did not run a laboratory test on the fuel in question, but after we had a disposal company remove the old fuel and we filled the tank with fresh # 2 diesel the engine problem cleared up.

During the ice storm the fuel contamination problem was clearly microbial. We found slimy black/gray material in the filters of the units that failed. The volume of contaminate was so great we could not always keep ahead of it. It surfaced in four generators-three portables and one stationary and may be present in other units as well; therefore, all generators fueled by the vendor who fueled the affected units need to be tested. All tanks found to be contaminated must be cleaned. A "Fuel Polishing" company may be retained for this work.

I have enclosed articles from the Hastings filter company and Martin's Marine that deal with the nature of fuel contamination. Other articles on this subject can be found on the Internet if you would like to research the issue.

Water contamination and microbial contamination go hand in hand. In order for the microbes to grow, water must be present. In the markets we serve, we use the water finding paste method to detect water as mentioned on Martin's page two. We perform this procedure each time we service a generator and we seldom find water. Because of our procedure I am confident microbial contamination is not developing in your systems.

However, contamination may be added when you buy fuel. The contaminant can grow in the fuel supplier's storage tank and then be pumped into yours when you have them topped off. It can affect just a few of your units or all of them. It depends on which units get the bad fuel. Also, the quantity of contaminate can vary so that some generator filters take longer to plug than others. In Greensboro some affected units were so contaminated we could not obtain and change fuel filters fast enough to keep the systems up.

We will continue to check for water. In addition, I recommend you have your own technicians check for water each time you buy fuel. Also, have a serious talk with your fuel supplier. Ask what procedures he uses to prevent contaminating your tanks. A final filter on his delivery system will assure you that you are buying clean fuel.

I suggest you check out "Fuel Polishing" systems and procedures on the Internet. They can run from simple to extravagant systems and services. Shirley Environmental Testing LLC is a good place to start.

1-16-03
Paul Harris