Fuel contamination: The importance of fuel filters

The challenges

These days, diesel contains a percentage of biofuel (normally up to 7%) which causes microbial contamination (often known as diesel bugs; micro-organisms that grow on water present in fuel).  This leads to failing equipment, with contaminated fuel inside storage tanks causing, amongst other issues, pumps to block. In some severe cases, vehicles have stopped working. This, of course, results in unwelcome downtime and hefty repair bills.

Put simply, a tank becomes an incubator; as the variation of temperature, condensation and the added percentage of biofuel (which attracts water as it is hygroscopic) helps these bugs to flourish. Over a period of time, these living microbes grow into large colony forming units (CFUs) which get sucked into fuel supply lines, blocking filters on dispensing pumps and vehicles.

Microbial contamination is most commonly seen as sludge that forms in the bottom of storage tanks and accumulates on filters. This sludge also contributes to poor emissions (seen as black exhaust smoke). And, of course, if you use pure biofuel, the problem is compounded further, as biofuels can contain up to 25 times more water than mineral diesel, increasing the risk of serious and expensive damage to fuel injection systems.

Other factors that increase the risk of contamination

The rate of usage: The longer fuel spends sitting in the tank, the more likely it is to build up contamination through condensation and microbiological growth.

The location of a tank: Condensation builds up when the tank breathes; when it lets air in and out as fuel is used, replenished, and as the fuel shrinks and expands with temperature. The temperature of fuel in a below ground tank is more constant throughout the year and so should breathe less. Naturally, this means above ground tanks are more susceptible to condensation build up. When exposed to the sun, they breathe more than a tank sited in a more sheltered location.

The age of a tank: The longer the tank has been in use, the greater the build-up of internal silt and scale. Although this usually collects out of harm’s way at the bottom of the tank, deliveries to the tank stir up this sediment and over the years the depth of silt can start to reach the outlet level.

The frequency of cleaning: Obviously the more often the tank is cleaned out, the less risk of contamination. However, even regular annual cleaning cannot prevent a rapid build-up of contamination.

Tank Maintenance: If the tank is not properly maintained it is likely to corrode, adding further to contamination levels.

The weather: The better the weatherproofing, the less the chance of rainwater seepage into the tank. An offset fill pipe is much better than a direct manlid fill, but leaky vents, tank gauges and pipe joints can all let water in.

The solution 

It’s relatively simple; fitting a spin on filter to your bulk diesel/HVO storage tank. The best option is to choose a 10-micron filter element, which will remove any particles and dirt. Our bestselling filter kits/spare elements have the water removal option with a combined 10-micron dirt filter, removing water and thus eliminating the breeding ground for the diesel bugs.

At Hytek, we offer a wide-range of filters. More than that, we offer our experience and service. If you’d like to talk to us about the best filter for your unique needs, then we would be only too willing to help.

Top tips to maintain a healthy tank

As well as fitting the right filters, there are a number of other measures you can take to maintain a healthy tank. So, we’ll leave you with these.

• Regularly check for the presence of water.
• Inspect your tank, checking for points of water ingress.
• Bottom out your tank to remove any free water & sludge.
• Have your fuel tested regularly for microbes.
• Fit a fuel conditioner to your suction or vehicle fuel lines.
• Fit a water & particle filter to your storage tank (fit to delivery side of pumps).
• Use tank dryers in fuel stores & vehicle tanks when not in use.