Technical
GIVEN much THOUGHT to your RED DIESEL lately?
The fact that the specification for red diesel (BS2869:A2 gas oil) changed significantly in January last year passed many people by, including, it has to be said, many regular users. This is not to say that regular users of red
diesel aren’t experiencing problems or aren’t questioning the operability of their machinery - in fact, the reverse is true. So, what is going on, and what has changed?
Neil Ryding, Managing Director of FAST )
Fuel Additive Science Technologies), explains
scales on emissions reduction from their engines. As a result, a huge amount of time and effort has been, and is being, devoted to the mechanical design of an engine and its exhaust system in order to minimise noxious gaseous and particulate emissions. Consequently, ever tighter tolerances are being seen in the sophisticated fuel injection systems in an attempt to maximise combustion efficiency, and the inclusion of sensitive exhaust after treatment devices is now commonplace. So far, so good on the engine, but is the UK’s red diesel up to the job? This question is important, as the vast majority of modern engines are calibrated to run on DERV – EN590. Evidence over the past 12 months suggests that many vehicles running on red diesel require a little ’help’ if they are to operate at optimum performance.
T Fuel
Since the start of 2011, in order to help with the performance of catalyst-based exhaust treatments, and via an EU Fuel Quality Directive, the maximum sulphur content of red diesel for mobile non-road engines (i.e. tractors, backhoes etc) was cut by a factor of 100 (to 20ppm at the point of delivery) whilst, simultaneously, the maximum biodiesel content can now
he manufacturers of modern diesel engines, whether they be for on-road or off-road use, are coming under increasing pressure to comply with stringent time-
rise to 7% by volume. The cetane number was unchanged at 45, but this is also critical.
What Does This Mean for the End- User?
Lowering the sulphur content of a fuel is nothing new: road diesel and petrol jumped this hurdle without much problem some time ago. Talking sulphur out, however, does reduce the ‘oilyness’ of fuel – its natural lubricating properties - as during the removal process some extremely useful lubricating hydrocarbons are also lost. This matters, as a lower fuel ‘lubricity’ results in excessive or premature wear in the very close-tolerance parts of common-rail injection pumps and injectors. The current specification does counter this by specifying a lubricity measure, and fuel supplied to this specification should, of course, cause no problems. Note that fuels substantially exceeding this minimum lubricity specification can benefit from improved fuel economy.
The second change affecting the maximum biodiesel content is potentially the more questionable. At a maximum 7% by volume, it is now equivalent to the DERV specification. Whilst more biodiesel in the fuel does increase its lubricity, it does have a number of downsides, including:
• a much-increased water pick-up potential, leading to a decrease in
FEBRUARY/MARCH 2012 PC 119
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