Farmers from across the length and breadth of the UK have been reporting problems with red diesel. Having been encountered for a number of months now, the problem seems to be on the rise with many saying filters are needing frequent changing.
The root of the problem appears to be an increase in the prevalence of bio-diesel known as Fatty Acid Methyl Ester (FAME) added to farm grade diesel, which has been capped at seven per cent since 2011, after rising from five per cent. While the level of inclusion has not changed for sometime now, the chances of FAME diesel arriving on farm have increased, thus the increase in incidences of blocked filters.
Jill Hewitt of the National Association of Agricultural Contractors (NAAC) says; “The NAAC is reviewing the problems with fuel, having been inundated with complaints from concerned contractors having to regularly change blocked filters on tractors, combines, foragers and other machinery.”
From consultation with a number of contractors, many report filters having needed to be changed after as little as 100 hours, with some even keeping several spare filters in the tractor cabs.
Many have reported low fuel pressure as a result, although it appears more modern and sensitive engines are particularly susceptible.
The UK and Ireland Fuel Distributors Association says the increase in FAME renewable fuels is forced by legislation. In April 2018, the legally required percentage of fuels derived from renewable sources increased to 7.25 per cent and from 1 January 2019, it rose to 8.5 per cent. As expected, this has led to FAME being introduced into gasoil supplies in the UK.
It says however, that the fuels supplied by its members comply with BSI specification, with the maximum inclusion of FAME at seven per cent. It does however recommend addressing storage concerns with water ingress in unprepared storage at consumer premises top of its list of short comings. This includes condensation build up in tanks, with the biodiesel element holding water in the fuel.
FAME has been added to fuels, not only for environmental reasons, but also lubricity within the combustion chamber, since the amount of sulphur present in fuels has been drastically cut to 10 parts per million with the advent of emission-friendly engines, which cannot cope with high sulphur levels. The sulphur in the fuel acted as a lubricant and also as a natural biocide, keeping fuels free of diesel bugs.
Diesel bugs as explained by Peter Weide of marine engine experts, and increasingly involved with ag machinery, MarShip UK are yeasts, moulds and bacteria that live in water and feed on the diesel. They can double in number every 20 minutes. Seeing as FAME is very hydroscopic, up to 30 times more water is absorbed in to the fuels, with little to no biocide in delivered fuels.
He says it is imperative to reduce the chance of water coming into contact with the fuel. This includes keeping tanks full to stop condensation build up. Where farms are concerned, he says the turn over of fuel is an important factor, with those storing fuel for extended periods of time needing to be mindful of draining off water from the bottom of tanks and considering additives to stabilise the fuel.
Modern low sulphur diesel is nowhere near as stable as it once was, with instances of compounds settling out of the fuel, causing gumming of filters and lacquering of engine parts, as well as reducing the cetane number of the fuel, thus overall performance of the burn is reduced. Additives with detergent to stop this as well as diesel bug inhibiting enzyme and killing biocides are widely available and a good bet says Mr Weide. Likewise, it could be a good idea to have storage tanks professionally cleaned now this problem has emerged, before refilling and treating with additive.