Fuel Test Kits and Supplies that Provide
Periodic Updates on the Condition
of Your Stored Fuel

Liqui-Cult Test Kit
Comparison Chart

Liqui-Cult Comparison Sheet

FuelStat Sample
Test Kit Results

FuelStat Sample Tests

Additional Literature
for Fuel Testing Kits
and Supplies


Liqui-CultTM  Fuel Test Kits

Liqui-CultTM test kits are used to detect microbial growth in fluids, in the laboratory and in the workplace. Areas of application include metalworking fluids, circulating cooling and process water, hydrocarbons (diesel fuel), and other liquids such as cleaners, cosmetics, liquid soaps, detergents, etc.

Liqui-CultTM testing determines the type and degree of infestation usually measured by the more expensive plate count system. To use, simply fill the 5 cc syringe (included in your kit) with the fluid to be tested. Inject the complete 5 cc’s through the rubber cap of the test bottle containing the liquid agar and shake it vigorously. Incubate for 30 hours for bacterial growth or 72 hours for fungal growth and compare it to the appropriate photo charts to determine the degree of contamination.


  • Capture a fuel sample in a clean dry container.

  • Assemble syringe by first removing plunger nozzle guard. Take cap, not guard, off needle and press into plunger nozzle, leaving needle guard in place until ready to use.

  • Remove needle guard and insert tip into liquid to be tested. Draw plunger back, filling syringe with complete 5 cc’s of fluid.

  • Inject needle through rubber cap on bottle and push down on syringe plunger, emptying contents completely into it. Remove syringe from bottle, replacing needle guard and discard according to local, state and federal guidelines. Shake bottle vigorously to mix fluids.

  • Incubate bottle at room temperature for 30 hours for microbial growth and 72 hours in total for fungal growth.

  • Bacterial/Microbial Growth: After 30 hours compare the color of sample bottle to the color chart.

  • Fungal Growth: After 72 hours compare the color of the test bottle to the color chart.

  • If it is necessary to dilute samples to be tested, for reasons of viscosity, etc., the following procedure is recommended: A sample may be diluted by adding 1 ml to 99 ml of boiled, cooled tap water in a clean container. Add 1 ml of the test sample to the diluent, cap the container and shake vigorously. Then proceed with the above directions. Take the dilution factor into account when estimating growth. For example, a 105 count from a 1/100 dilution of fluid would indicate 107 organisms per ml in the original sample.

  • STORAGE: Liqui-CultTM should be stored at room temperature (68-75 deg. F). Protect from light. Need not be refrigerated.

  • DISPOSAL OF USED MATERIALS: Under a fume hood fill the bottle with bleach. Allow to stand for 24 hours. Then discard in an appropriate manner. Needles and syringes should be disposed of within local, state and federal guidelines.

Note that in performing testing where a biocide or other similar product has been used in fuel, the test will likely result in a false negative reading for microbial and fungal contamination, but fuel degradation and contamination from other sources is common and the test will not disclose other problems.

FUELSTAT® Diesel & Jet Fuel Test Kits

FuelStat ContaminationThere are a number of microbes that can degrade fuels. These microbes tend to work together as a consortium, which often leads to compounded contamination throughout the tank and entire fuel delivery system.

The most dominant of these microbes is Hormoconis resinae (H.res). H.res is more commonly referred to these days as The Diesel Bug. H.res is present in approximately 70% of all cases of contamination in diesel fuel. The remaining 30% is made up of bacteria and/or other fungi (including some yeast). This consortium works together in the vast majority of cases of diesel fuel contamination. However, the recent introduction of bio-diesels appears to be shifting the balance in such consortia towards yeasts and other filamentous fungi, so it is important for the test you use to detect all organisms present.

Bio-Diesel Testing

Bio-diesel is already proving to be problematic with the Fatty Acid Methyl Esters, or FAME, being far more susceptible to microbial attack. FAME can stick to metal surfaces, such as in pipelines and tankers. When it does, it can then be drawn out into other fuels passing through or being carried, thereby adding FAME to non-FAME fuels like diesel or increasing the percentage of FAME in other bio-fuels. There is growing evidence that the presence of FAME in fuels increases the speed with which contamination growth becomes a problem.

FUELSTAT® technology provides in-the-field, rapid screening of fuel samples (water in fuel or just fuel), giving a quick and accurate assessment of microbial contamination in real time and shows whether you have low or high levels of contamination in aviation and diesel fuels. Most importantly, it gives results within 10 minutes unlike current growth-based tests which must be incubated and monitored for a minimum of 72 hours to provide any results.

Fuel testing kits currently available, which involve total microbial counts, simply tell us that there are micro organisms present in the fuel and that they are alive. FUELSTAT® resinae diagnostic test goes beyond this. Because it detects only active H. res., bacteria and fungi. It tells us not only that the fungus is present and alive but also that it is growing and, therefore, the potential for damage is real.

FuelState DropperThe FUELSTAT® test measures the amount of different types of contamination: H Res, bacteria and fungi actively growing in the sample and reports that as the weight of material in the sample. This is a newer, more accurate, measurement system than the old Colony Forming Unit (CFU) count and provides action and alert levels.

Please see the Instructions available in .pdf format under the FUELSTATE® section on the left side of this page.

The FUELSTAT® Test Kit results correspond to the recommended limits set out in the IATA’s (International Air Transport Association) Guidance for Microbial Contamination.

The Sample Tests shown on the left side of this web page provides results displayed based on a traffic light scenario. Compare the lines shown in the viewing window to the lines on the supplied comparison card:

** Use of an AXI Fuel Conditioner is recommended as a long-term solution. The AXI Fuel Conditioner can be mounted in the fuel line on vehicles, equipment, marine vessels, etc. For service facilities or for storage tank installations, a portable or installed AXI Fuel Conditioning & Tank Cleaning System is recommended. All Systems (whether a TK Series Portable System, an MTC Series Cart or Pallet Mounted Mobile Systems, or an STS 6000 Series or 7000 Series Automated System) operate on the same philosophy, but the optimal System for your application is dependent on tank size, location, and desired amount of automation in the process).


ASTM D6469 14 Standard Guide for Microbial Contamination in Fuels and Fuel Systems, Section 8.5 states:

“Samples for Microbial testing should be kept on ice for transport to the laboratory. Tests should be performed within 4 hours and no later than 24 hours 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.”

Kolor Kut Water Finding Paste

To determine the amount of water and sludge in a tank an old and tried method is called “sticking the tank.” This means using a stick with “Kolor Kut” paste on the end of a stick or a tank measuring rod that reaches through the top fill opening all the way to the bottom of the tank. Kolor Kut paste, available through our Shopping Cart in a 3 oz. (85g) tube, will show the water level in the tank by changing color where it comes in contact with water, indicating how much water and sludge will need to be removed.

Kolor Kut Water Finding PasteRegularly checking any fuel tank is an important part of a maintenance program. Water in above-ground tanks can freeze causing damage, and below ground tanks with water provide the ideal environment for microbial contamination to grow at the interface between the water and the fuel, or other hydrocarbon fluid, in the tank. Learn more about what causes and how to fix bad diesel fuel.

Removal of water depends on the type of tank. Fuel tanks on equipment can be pumped out using a 1/2 inch length of rigid tubing. PVC pipe or PEX pipe can be used.  Use it like a soda straw in a soft drink. Cut the tubing to length so it will reach the bottom of the tank and allow you to hold your thumb over the end. Cover the end with your thumb and place the tube into the tank to the bottom while you continue to hold your thumb over the end. When you reach the bottom of the tank, remove your thumb so whatever is in the bottom of the tank enters the tube from the bottom. Then replace your thumb, holding the contents of the action inside the tube. Remove the tube and empty the contents of the tube into a empty 2-liter soft drink bottle that has been placed inside a 5-gallon bucket (to catch any spillage).  Repeat this process several times until the drink bottle is at least half full.  You may need to allow the contents of the drink bottle to settle overnight.  Inspect the contents to determine if the tank contains all fuel or has water collected at the bottom, and what type of debris or other materials came from the bottom of the tank.

If several inches of water is found accumulated in the tank bottom, the portable DC powered TK Series TK-240 XT Portable Fuel Conditioning & Tank Cleaning System is the ideal tool for removing water and other debris from tanks up to 1,000 gallons. Larger tanks or commercial applications where the removal of water and debris is done often requires a more substantial system such as one of the STS 6000 Series or STS 7000 Series Automated Tank Cleaning Systems or a MTC Series Mobile Tank Cleaning System.

WE-12 Water EliminatorShould the water you find be minimal, do not ignore it as the consequences can be just as problematic to the cleanliness and performance of your diesel fuel. With small amounts of water in any fuel tank, utilizing a Water Eliminator to remove water is a low cost, easy and effective way to capture the water from a tank bottom and remove it. The Water Eliminator contains crystals that will absorb water but not diesel fuel. Inspect the Water Eliminator at each tank fill and when the crystals have swollen with water, replace the Water Eliminator with a new one. Larger storage tank size Water Eliminators are also available.