Why Test Diesel?

Today’s common rail diesel engines, with injection pressures up to 35000psi, are intolerant of even the slightest fuel contamination.

Abrasive particles and water will quickly cause damage and result in equipment downtime and the fine engine filtration designed to protect the equipment can easily become clogged if any microbial bio-mass is present in the fuel storage tank.

Some forms of contamination in your fuel tank can cause other types of contamination, for example if free water is present in diesel fuel, it will promote the growth of diesel bug (also known as fuel bug). Water will also accelerate diesel fuel oxidation, which can lead to the formation of acids and gums in your fuel.

When stored for long periods of time, the latest specification of diesel fuel, or gas oil, can start to deteriorate as it can contain up to 7% biodiesel. Biodiesel is less stable than petroleum diesel and is more prone to oxidation, it is also more hygroscopic than and will absorb moisture from the atmosphere. As ambient temperatures change this moisture condenses out of the fuel to form free water at the bottom of the fuel storage tank – this is the breeding ground for diesel bug.

Major fuel companies and engine manufacturers are now recommending that, wherever diesel is being stored for long periods of time, a fuel management programme is introduced to monitor and maintain fuel quality. A key component of such a fuel management programme is regular fuel testing.

By testing your fuel for water content, for bacteria in fuel and general cleanliness you can prevent the possibility of premature engine fuel filter blockage, unscheduled maintenance and equipment damage and downtime. Where fuel is being stored for a safety critical application such as a fire pump or standby generator you will have the certainty that your fuel will be in prime condition when you need it most.


Bio-diesel & Water

Fuel legislation designed to reduce harmful emissions and increasing global demand for diesel has resulted in more and more bio-diesel finding its way into the fuel supply chain. The increased use of bio-diesel will increase the incidence of water contamination problems in diesel.

Why? Bio-diesel contains more water than petro-diesel (it is introduced in the production process), it is also hygroscopic – it absorbs water from the atmosphere. Petro-diesel can absorb around 50 parts per million (ppm) of water whilst bio-diesel can absorb as much as 1500ppm – most global fuel standards recommend a maximum water content of 200ppm. As ambient temperatures rise water is absorbed into the fuel, as they fall the water condenses out of the fuel and forms free water at the bottom of fuel tanks. Free water can wreak havoc in your fuel system.

Water in your fuel can cause: Potential damage to your engine


  • Engine misfiring and lower power input Fuel injectors can get clogged and fuel delivery and injector spray patterns are affected
  • Wear to fuel injector and pumps Water is a very poor lubricant and metal on metal contact occurs resulting in scuffing and wear
  • Corrosion of fuel system and engine parts Steel components will rust in the presence of water
  • Explosive damage to fuel injectors The combustion process will superheat any water present which can cause injector tips to be 'blown off'
  • Acceleration of fuel oxidisation. The oxygen in water acts to speed up the process of fuel deterioration