Frequently asked questions

The test line is very faint, does that mean that it is positive?
No, if you can see a test line, even a faint one, that has a definite colour (i.e. is not a shadow) then the test is negative. This is due to the fact that the line does start to fade when the contamination level is near to the action levels, and then disappears when it exceeds the limit. So, if you can see a line then the level is below the cut-off point, so the test is negative.

Do I need to incubate the sample or the test paddle?
No, unlike other traditional growth methods used by our competitors, no incubation is needed for FUELSTAT® .

No lines have appeared, why?
This usually means that the blue liquid has not been allowed to settle fully in the Sample Extraction Buffer bottle so that neat fuel has been added to the test well. As the test fails-safe, no lines will be seen. However, the test cannot be reused and a new foil pack must be opened.

Are the control lines supposed to be brighter than the test lines?
Yes, the control line shows that the kit has operated properly and should be very distinct. The test line is a response to the level of contamination in the fuel and is usually less bright.

We routinely biocide our storage tanks, what added value would FUELSTAT® offer us?
This question supposes that the system you currently operate includes draining water and then biociding the fuel in the storage tank. Draining the water from the tanks is the key basis for any control system. However, there are problems associated with routine biociding. Firstly, it involves costs in terms of manpower and the biocide itself. Next, there can be problems with warranties from the engine manufacturers if there is any doubt about the ppm levels of biocide in fuel. Routine use of biocides has risks in two areas; firstly there are health and safety considerations in the use of biocides; we suggest that its use should, therefore, be restricted to the minimum required to maintain clean fuel. Finally, unless the correct ppm level is maintained throughout the soak period, there is a danger that a resistant strain or strains of microbes will be produced. This last is the main reason why the preventative or maintenance dose has been removed from the options available to airline engineers in the new IATA Guidance Notes.

The introduction of a monitoring regime using FUELSTAT® resinae has enabled maintenance engineers to have real-time information on the state of the tank, allowing them to base decisions on any remedial actions on accurate data. No resource time or expense is wasted on unnecessary treatment or other actions. As the FUELSTAT® resinae test requires only one sample per tank and takes 10 minutes to operate, it is a quick, accurate and easy method to operate.


Any other 'specialist' equipment required?
The only other items of equipment needed are the normal safety equipment (gloves etc) and the sample bottles necessary to hold the fluid. Other than that, the test is “stand-alone”.

Does it have any reaction with the biocides?
The basic answer to this is, “no it does not”. In an aircraft context, there should be a delay between biociding and retesting to see whether the biocide has been totally effective. This is done to ensure that all treated fuel has been consumed through the engines. This is obviously not possible in a storage tank scenario. In your circumstances we would suggest retesting a week after the biocide has been introduced into a contaminated tank. that would mean that we would be looking for traces of any surviving microbes, not the residue from that which has already been killed.

FAQs about the diesel bug in diesel fuel,  and the jet fuel fungus in aviation fuel;

Diesel Bug & Jet Fuel Fungus Contamination

Why is there a problem with diesel bug microbes?
Micro-organisms are present wherever sources of food and water exist together. In a fuel system fuel provides the food source, whilst water comes from the fuel itself as well as from external sources like atmospheric humidity, cooling systems and the moisture attractant, (hygroscopic) nature of biofuel.

Why should I worry about having the diesel bug in my fuel system?
Water is heavier than fuel and so is found at the bottom of tanks &stores. Microbes tend to live at the water fuel interface, living in the water and feeding off the fuel. They also seek out low flow areas of fuel system and are known to over time to actively create these conditions by ‘digging in’ to structure of tanks and lines, resulting in corrosion and pitting. Heavy contamination can block filters and stop engines too.

Why is the diesel bug problem getting worse now?
Governments worldwide are taking measures to reduce emissions and eke out dwindling fossil fuel stocks. There is also an imperative to reduce the economic risk of and politically unacceptable dependence on fossils fuels and their suppliers. The emissions drive has led to sulphur, seen as the main culprit in the emissions issue, being targeted for reduction. Adding biofuels to fossil fuels is seen as the best current solution to eking out fuel stocks and spreading risk.

Tell me more about Sulphur
Sulphur is a lubricant and so cutting its levels increases fuel system wear and reduces efficiency. Older engines in particular suffer from its reduction. Sulphur also is a bacteria-stat. This means that it interferes with the lifecycle of bugs and slows down their ability to colonise the fuel system.

Share this on: