Marine fuel testing for microbial contamination: a practical guide
In many of these cases, the fuel was on-specification and didn’t have dangerous levels of contamination when it was uploaded. Microbial contamination can grow quickly in short time periods—so testing your marine fuel is very important.
Read this 10-minute guide to learn the facts and choose a marine fuel test that suits you.
Why marine fuel management is becoming more important
With less sulphur in fuels, it may become easier for microbial contaminants to grow and flourish, although this is not as yet an established fact. These contaminants, often called diesel bug, or diesel fungus, can seriously affect fuel quality and cause costly damage to engines.
If you’re an MGO user, these changes mean it’s vital to conduct a regular fuel management programme that includes testing for microbial contamination.
After IMO 2020, it seems likely that fuel costs will increase as demand outstrips supply. With that in mind, it makes solid financial sense to minimise any potential risks to your expensive refined MGO. The keys to doing this are improving fuel management and conducting regular marine fuel tests.
Further consideration should be given to vessels with dual fuel capability which requires the switch over from Heavy Fuel Oil (HFO) to Marine Gas Oil (MGO) upon entering Emission Control Areas (ECA). In this situation, microbial contamination can occur within the MGO during a vessel’s passage through open waters and the management of this precious cargo is essential to minimising the potential risk of fuel supply issues upon fuel switch over. The use of FUELSTAT® provides a vessel with the ability to test for the presence of microbial contamination during transit and take informed decisions on any remedial requirements that may be needed.
FUELSTAT® off-shore marine fuel test – FUELSTAT Diesel Plus (FMD8)
Test for all known microbes that are dangerous to fuel in just 15 minutes
What is diesel bug - microbial contamination, and how does it affect marine fuel?
Microorganisms are found virtually everywhere where fuel is found, entering through air and water. They can feed on components of the additives or on fuel hydrocarbons and are capable of multiplying at an incredible rate.
Diesel bug microbial contamination creates a slime called a biofilm or biomass that can cause several issues. If left for long periods without treatment, it can:
- Block filters
- Wear injectors
- Stop engines from working
- Induce corrosion, potentially resulting in tank leakage
To prevent this, many fuel manufacturers recommend complete fuel tank drains and cleaning on a periodic basis.
In addition, there are several tests that can detect microbial contamination levels to determine if fuel treatment is necessary. The fuel systems in ships are a perfect habitat for microorganisms to live and grow in, so it’s sensible business practice to use these tests.
How can diesel bug be controlled?
Does removing water prevent diesel bug?
This advice is still totally valid today. However, it’s now much more difficult to effectively remove water from diesel and MGO that contains biofuel.
Biofuels often contain FAME (Fatty Acid Methyl Esters). This material is extremely hygroscopic—in other words, it absorbs and holds on to water more than traditional mineral diesel. In fuel containing FAME, free water can usually be found at the bottom of a tank. But above this free water layer, there is often a hazy layer of suspended water.
While the free water is fairly easy to drain away, droplets of water often remain in the fuel. It is very difficult to remove these droplets. And wherever there is an interface between fuel and water, the dangerous microorganisms can live and multiply.
What are the options for testing marine fuel?
Generally, an on-shore test that takes several days and is conducted in a sterile laboratory by highly-trained specialists.
Alternatively, there is a method called thixotropic gel that can be done on -site but also requires the same incubation as with all CFU growth tests.
A fast test that can be carried out off-shore using specialised equipment. Extensive training is required.
A rapid modern type of on the spot test, often used when operational at sea, which can be carried out without any special equipment and without needing extensive training.
We’ll take a closer look at all three marine fuel tests after a quick note regarding on-shore testing.
Is sending samples onshore for marine fuel tests worthwhile or economical?
Marine fuel tests
CFU Growth Tests: a catch-all on-shore marine fuel test to detect microbial contamination
The technician who did the test then manually interprets the results by referencing agreed industry limits for contamination. If unsafe contamination levels are detected, treating the fuel will usually be the next recommendation.
However, the broad testing scope makes it impossible to understand exactly what the microorganisms are, and whether they’re threatening to marine fuel systems. When contamination is detected, the result might actually be a misleading result. Without further laboratory analysis, there’s no way of knowing.
A misleading result means that costly fuel treatment may be recommended where none was actually required. In addition to the cost, using biocide treatments too often is problematic. Biocide requires strict handling and application, and if used too often, can lead to the microorganisms becoming resistant to the treatment.
ATP: a highly technical off-shore marine fuel test
However, it does require purchasing an expensive hardware unit if this was to be considered by ship owners. So, ATP may not be an option for many ship owners, fleet managers or fuel bunkering companies who do not test large enough volumes to justify the expenditure.
ATP testing must also be carried out by trained technicians with laboratory experience. Results are given as a number (concentration of total ATP present in the sample), and the technician who conducted the test has to interpret it against set industry limits for contamination. Like IP385, ATP is a ‘catch-all’ marine fuel test that doesn’t specify what microbes are found, meaning misleading results are possible.
Immunoassay: rapid testing at sea to detect microbial contamination
It can be carried out on a boat, on the spot, and requires very little training to use.
Immunoassay is unique because the technology only searches for specific microorganisms that can thrive and do damage in marine fuel systems. The outcome is that cross-contamination from other microorganisms is no longer an issue, and the likelihood of misleading results is greatly reduced.
The method gives clear and simple results, requiring very little interpretation from the tester. You get a clear readout explaining what groups of microbes are present and what is the contamination level, without the need for calculation or cross checking.
FUELSTAT® is the immunoassay Marine Fuel Test that takes just 15 Minutes
It can be used wherever fuel is manufactured, stored, distributed or consumed, in as little as 15 minutes.
This is the only test available that detects all known organisms affecting fuel systems, while ignoring harmless ones. Unlike with CFU or ATP tests, there is almost no chance of false positive results. It provides simple alert levels that can be used to inform remedial actions—all without any special skills or equipment.
FUELSTAT® is sold in over 130 countries and trusted by 400 airlines (and counting). It is fully compliant with International Standard ASTM D8070.
Learn more about FUELSTAT®
See how FUELSTAT® can save you time and money by testing for marine fuel contamination early.
Test for jet fuel contamination in 3 easy steps
Drop fuel samples into FUELSTAT® test kit
Scan the kit with the FUELSTAT® Result app on your smartphone
See full Analysis Report from the app on FUELSTAT ® Result Portal, with all results stored for later retrieval and analysis