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Diesel Generator Fuel Testing

FUELSTAT®: The 15-minute Diesel Generator Fuel Testing Kit

Check your generator fuel for microbial contamination with the latest immunoassay antibody test kits.
  • ‘Test at the tank’ technology—no laboratory required
  • Accurate results in 15 minutes or less
  • Tests can be conducted by a single member of your team
  • No scientific background or in-person training needed
  • Log and share results digitally with the FUELSTAT® app

Backup power generator
fuel testing

Is your backup generator 100% ready for a power emergency?

In a power emergency, your generator fuel is just as important as the generator itself.

And at times when power emergencies seem more likely—or have greater consequences — you need to be 100% sure your fuel is usable.

That means carefully monitoring and managing microbial contamination (a.k.a diesel bug) because:

  • Backup generators are at high risk of microbial contamination. Modern diesel fuels always have at least some level of microbial contamination. And when fuel isn’t changed often, contamination has more time to grow to dangerous levels.
  • Severe microbial contamination could mean disaster. If contamination grows quickly between tests, it could potentially stop your generators working.
  • Traditional fuel tests are inconvenient. Testing for contamination usually involves hiring an external team, sending samples off-site, and waiting days for results.
  • Contamination risks are often underestimated. Many maintenance contractors do not realise how fast diesel bug grows, or the danger it presents.

The only way to have total confidence in your generators is with a fuel maintenance program that incorporates regular, accurate testing — so there’s 0% room for error.

An outdoor generator that has recently had to undergo diesel fuel testing using the 15 minute Fuelstat® test.
A light-green emergency generator that is in need of diesel fuel testing for microbial contamination.

Emergency Generator
Fuel Testing

Why is emergency generator fuel at risk?

Middle distillate fuels can be affected by contaminants like water, particulates (e.g. rust and dust), other fuels, and microbial contamination.

Microbial contamination can enter through water droplets, which get into fuel systems largely through condensation and grow in the space between water and fuel.

Diesel fuel is particularly at risk of microbial contamination due to its properties. In the last 10+ years Fatty Acid Methyl Ester (FAME), also called biofuel, has been added to diesel. FAME is susceptible to microbial contamination because it attracts and holds water.

Once this microbial contamination starts to develop, it can get out of control quickly. The microorganisms produce a thick, slimy material called biomass, which clogs engines and stops them from working properly. Biomass can also influence metal corrosion, causing permanent damage to tanks and mechanical parts.

FUELSTAT® Generator Fuel Testing Kits

Test your fuel for microbial contamination on-site in just 15 minutes

How can you defend your diesel generator against biological contamination?

There is no way to completely prevent microbes from entering fuel. These microbes are all around us, in the air and on surfaces, and can enter the fuel in numerous ways once it leaves the refinery.

Most importantly, even the well-maintained fuel delivery systems will experience condensation—and when water gets into fuel, microbes do too.

If severe microbial contamination is discovered in your fuel, it can be treated with specialist fuel cleansers and biocides. However, this procedure can cost many thousands of dollars and usually requires taking your fuel and generators out of action.

Read more >> Diesel Fuel Contamination Test Kit // Diesel Bug // Diesel Fuel Contamination

Preventing the growth of microbial contamination is the most effective treatment.

The safest plan is to follow a fuel maintenance program that monitors and minimises the growth of microbial contamination. Regularly removing water from your fuel tanks makes it difficult for dangerous yeasts, bacteria, and filamentous moulds to grow.

However, it’s equally important to test your fuel regularly. Catching microbial contamination in earlier stages allows you to make informed decisions about how to deal with the threat. This has two main benefits:

1. Protecting generator performance. You won’t risk the contamination getting out of hand and affecting the performance of your generators (or worse, putting them out of action).

2. Saving money. You can treat the fuel before it gets to advanced stages, saving your organisation from spending many thousands of dollars on sophisticated treatments (or on replacing fuel and equipment).

FUELSTAT® Generator Fuel Testing Kits

Test your fuel for microbial contamination on-site in just 15 minutes

What options are available for
backup power generator fuel testing?

There are three main methods available for diesel generator fuel testing.

CFU testing. Laboratory CFU testing requires sending fuel samples to an external lab under temperature-controlled conditions. The samples are then placed in an incubator, which encourages any culturable microbes to grow. Laboratory staff then measure the quantity of microbial colonies formed on the medium and use the results to make an assessment of the fuel.

CFU tests are also available in kit form, which can be conducted on-site. In order for the microbes to grow in the culture medium the kit has to be left for a few days in a secure location prior to assessment of the sample.

CFU tests potentially detect all microbes present in fuel, including those that aren’t harmful to fuel. Because of this, CFU tests may lead to misleading results where serious contamination is diagnosed, but the test is actually picking up harmless microbes.

If the fuel is handled and analysed by an external lab’s team, any delays or problems and you may wait longer to get results.

ATP testing. A piece of laboratory equipment called a luminometer is used to measure light emitted as a result of an ATP-mediated enzymatic reaction. This effectively means the test measures the amount of living microbial cells in the fuel sample.

This test can be conducted on-site, but it requires sterile laboratory conditions and specialist equipment, so is more commonly conducted off-site. And like with CFU methods, the test potentially counts all microbes present, which means misleading results may occur.

If misleading results lead to an incorrect diagnosis of microbial contamination, the next recommendation might be to carry out expensive treatments on the fuel. This could mean spending tens of thousands of dollars on fuel that is, in reality, perfectly usable.

Immunoassay antibody testing. This modern testing method only looks for the microbes that are dangerous to fuel. As a result, it can be conducted on-site, without laboratory conditions or specialist training.

The test kits come in a ‘pregnancy test’ format that requires you to place droplets of fuel into a test well—no expensive laboratory equipment is required.

They can be used within minutes of taking the fuel sample, enabling fuel users to comply with ASTM D6469 by testing their fuel within 24 hours. This on-the-spot testing also avoids all the handling and cost issues of transporting fuel, a hazardous good, off-site.

Immunoassay is the technology used in our own FUELSTAT® test kits.

Immunoassay antibody testing with FUELSTAT® is the only method that gives fast results without needing multiple people to handle, transport and test the fuel.

Immunoassay antibody testing is the only method that gives fast results without needing multiple people to handle, transport and test the fuel.

A fuel sample that has separated into the water at the bottom, the diesel fuel on top and the micro-organisms in between.

FUELSTAT®: the 15-minute generator fuel test kit that makes one-person testing possible

In critical times, you need a fast, convenient testing method—one that doesn’t require multiple people to complete the process.

Using FUELSTAT®, a single person can conduct tests at the tank after minimal training from our instructional videos. It works like a pregnancy test: just place droplets of the sample onto the test well and wait for the readout.

  • Works on-site in 15 minutes or less
  • Easy-to-read results in ‘traffic light’ format
  • No specialist scientific training or equipment required
  • Accurate immunoassay antibody testing even in unsanitary conditions
  • Digitally record and share test results with the FUELSTAT® Result app

FUELSTAT® is used in over 130 countries and helps you comply with ASTM D6469 Section 8.5.

How to use FUELSTAT® kits for generator fuel testing

  1. Extract a sample of fuel and place 4 drops into each of the kit’s 6 test wells.
  2. Wait 15 minutes, then scan the kit with the FUELSTAT® Result app on your smartphone.
  3. Get a Full Analysis Report from the app on the FUELSTAT® Result Portal, with all results stored for later retrieval and analysis.
get in touch


    We have distributors around the world and can offer next-day delivery to most locations.

    Ideally you should follow the regulations of any governing bodies in your country. British regulators, for example, require generator fuel to be tested four times per year. 

    If there are no standard requirements for regular testing in your country, we would recommend that you still test four times per year. This is recommended by BS 5410-3:2016 if no fuel polishing is used. If you are using a fuel Polishing system, it is recommended that you test the tank twice a year.

    Regular testing is particularly important for hot countries, where high temperatures and humidity provide an excellent breeding ground for microbial contamination.

    In times where risks of power emergencies are higher, frequent testing can also give you greater certainty that your generators will be ready.

    Absolutely. In hospitals, fuel is often left in generators and fuel tanks for many months without being used or changed. Microbial contamination can grow to dangerous levels in that time, and in extreme cases, the resulting corrosion can cause fuel leaks. 

    FUELSTAT® allows hospital staff to perform quick, easy fuel checks as part of their scheduled maintenance routines. This enables you to detect microbial contamination in its early stages and make informed decisions around solving the problem. 

    In addition, FUELSTAT® tests can be carried out by an individual person from the hospital team. Hospitals can therefore avoid multiple people coming into the premises or having several individuals handle the fuel during the testing processes.

    The process is very simple and can be completed by anybody with a steady hand. We provide full training to your team, either in-person or through our existing instructional videos. It’s as simple as 1 2 3 – Test  – Result – Report.

    If you want to test your fuel for other contaminants (besides microbial contamination), using a third party maybe be convenient.

    However, if you only want to test for microbial contamination, using a third party isn’t necessarily the right choice. Many organisations still test using traditional methods that are more complicated than immunoassay antibody testing, requiring the fuel to be transported off-site and treated as a hazardous material.

    ASTM D6469 – 14, Para 8.3 – 8.6, Standard Guide for Microbial Contamination in Fuels and Fuel.

    Systems section – advises:

    It is recommended that ideally testing should be completed on site within a few minutes of sampling. Recognising that this is not always possible, it states that samples should be kept on ice in transit and tested within 4 hrs but no longer than 24 hrs after sampling. Samples stored at higher temperatures, or for longer times, can show the presence of microbial contamination that does not represent actual fuel system conditions.

    By using an immunoassay antibody testing kit, you can cut out the middleman and manage the entire testing process on-site yourself. That means potentially saving a lot of time and money, while reducing the number of people that come into contact with your generators, fuel, and surroundings.

    Easy to use

    No scientific training is required, and you don’t even need sterile testing conditions.

    Specifically designed for diesel fuel contamination testing

    The tests only look for microbes that are dangerous to fuel and ignore the rest.

    No special equipment needed

    Each FUELSTAT® test kit provides almost everything you need; you only have to supply a clean sampling bottle.

    Digitally verified results

    The test results can be scanned and stored using a free smartphone app, so it’s easy to check your records later.

    FUELSTAT® is compliant with ASTM International standard D8070 Standard and is used in over 130 countries worldwide.


    Learn more about FUELSTAT®

    Visit our site now to learn about how FUELSTAT® can help protect your business by catching diesel fuel contamination early