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Debugging Diesel Fuel

Is your fuel contaminated? The FUELSTAT® resinae PLUS test from Conidia Bioscience is an accurate, rapid onsite fuel test kit that detects the diesel bug in 10 minutes. Matthew Lardner, Sales Engineer from Global Services (Europe) Ltd — who distributes the product — gave us 10 minutes of his own time to tell us more.

A number of different micro-organisms (bacteria and fungi, including yeasts and moulds) can live, thrive and survive in marine fuel. Perhaps the most well-known and troublesome protagonist is the filamentous fungus, Hormoconis resinae, often referred to as the diesel bug. Hormoconis resinae (H. res) only requires a minimal amount of water to proliferate, but can grow to produce a significant biomass that results in filter blockages, corrosion, component failure and long-term damage.

The FUELSTAT® test rapidly screens fuel samples (water in fuel or fuel) to give a fast and accurate microbial content assessment, measuring the active growth in the sample and offering actions and alert levels. Quicker and more accurate than the traditional CFU (colony forming unit) growth based methods, the test result is determined by the weight of material in the sample and provides results based on an intuitive traffic light system (green = negligible; amber = moderate; red = heavy contamination).

"A key issue in the marine industry at the moment is fuel testing,” says Matthew. "When vessels take on fuel, they do a certain number of tests to check for particular aspects, such as making sure the flash point of the fuel is high enough and burns correctly, and ensuring it hasn’t been thinned out with methylated spirits or water. Other tests include a colour test to check the age of the fuel and a filtration test to assess the particulate content."

"Perhaps the most important test is screening for microbiological growth and any associated biological issues. The traditional growth based test, currently, takes at least 48 hours to indicate contamination. So, you’ve just taken on 100 m3 of fuel, costing €99,500 for example, and you don’t know — for 2 whole days — whether you have a microbial contaminant in that fuel. The knock-on effect is that should the fuel be contaminated, left untreated, this consortium of microorganisms can actually eat away at the integrity of surrounding metal: they can corrode the welds in the tank and the injectors, and the resultant biomass can severely clog up the pipework and filters," he adds, “so it’s not just the fuel you have a problem with." And, once you’ve taken on that fuel, and realised that you have a problem, remedial action needs to be taken. A mild situation can be dealt with by killing the microorganisms with a shock dose of biocide; however, the treatment itself can be difficult to ship because it’s highly flammable, dose rates have to be extremely accurately applied and overdosing can actually damage the engine fuel system or leave an apple jelly like sludge in the fuel tank.

"Should you have to debunker and get new fuel, there are huge cost implications, including cleaning, replacing filters and injectors … and downtime," notes Matthew. The FUELSTAT® test from Conidia Bioscience offers a fast, accurate, consistent, onsite diagnosis of whether you have a microbial fuel contamination problem or not. “Almost no fuel is clinically sterile, microorganisms or their spores are present in most middle distillate fuel at some level or another. The question is how contaminated is my fuel and at what level do operational problems arise? Much like a human pregnancy test, FUELSTAT® uses the same immunoassay technology to detect the consortium of microorganisms which make up the diesel bug. The test displays the results within 10 minutes to a negligible, moderate or heavy contamination level.
In terms of sensitivity, the test detects differing levels of microbial contaminant in water and fuel phases of the sample being tested. Both marine and aviation fuel, and all middle distillate fuels, such as kerosene, marine gas oil and diesel can be tested. No specialist equipment or skillset is required so FUELSTAT® can be used wherever fuel is manufactured, stored, distributed or consumed, and is capable of detecting all known organisms that grow in fuel or fuel systems. FUELSTAT® can even be used prior to bunkering as a quality assurance to check for unacceptable microbial content before loading on board.

"When you’re bunkering, you should take a sample at the beginning, half way through and at the end of the process. But, as these bugs are present in all fuel, growth develops at the fuel/water interface (as a result of condensation in the tank, poor tank aperture seals and suspended water within the fuel precipitating out to free water as the fuel cools) and should be monitored continuously by regular sump draining. It’s just good fuel husbandry," says Matthew, perhaps something like “I hope the message engineers take away from reading about FUELSTAT®, although it may seem quite expensive compared with the tradition 48 hour growth tests, in the grand scheme of things, if you bunker bad fuel, it’s a relatively inexpensive test!" Another issue is fuel that’s paid for in advance. It’s often difficult or awkward to reject or refuse to accept fuel that’s already been commissioned.
One of our clients recently had costs in excess of $100,000 USD to debunker/clean etc. not including rebunkering costs and the cost of two lots of fuel.

Advantages and Benefits
Beyond being fast, accurate and simple to use, the FUELSTAT® test provides immediate and actionable information on bacterial and fungal contamination. But, says Matthew, the clear benefit is that you don’t take on bad fuel.

“As an Marine Engineer in the Royal Navy, I worked with fuel every day," he comments. “I wish I had one of these tests then! You get an instant result, you know if you’re taking on bad fuel and, if you are, you can do something about it straight away. You don’t have to wait 48 hours, by which time the fuel will have got into your system, into your filters, etc. Granted, once it’s in your tank, you can treat the fuel with a biocide; and, regularly draining water from the bottom of the tank is a good strategy to minimise microbial growth; but why not take the pre-emptive step of not putting bad fuel into your boat in the first place?"

In the long-term, prevention is more cost effective than suffering heavy contamination and having to repair or replace an expensive fuel system and then having to face the consequences of owner displeasure or lost charter revenues due to vessel down time.  Additionally, with FUELSTAT®, there’s no capital investment required and you don’t get false positive results. When asked whether fuel companies should be using this test to prove that their fuel is good quality, Matthew says yes. “For example," he notes, “if you’re in the Mediterranean, overall, the fuel quality isn’t bad. But, in warmer more humid climes where microbial activity is greater you might not get access to high-grade, bug free fuel"


Fuel Husbandry
Rather than treat contamination when significant operational or fuel quality problems arise, it’s better to prevent microbial growth occurring in the first place. Much can be done to ameliorate the issues associated with microbial contamination in fuel, including
•    allowing fuel derivatives to settle in the tank for 24 hours before putting the tank back into service
•    drain any accumulated water from the bottom of the tank weekly
•    routinely test bottom samples for microbial contamination
•    treat fuel, if required, according to test results.


For more information please contact:-

Matthew Lardner - Sales Engineer
Tel: 0044 (0) 1392 354 300


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