Treatment to prevent degradation of emergency diesel fuel storage
We wouldn’t advise that diesel fuel is stored for long periods of time, especially for emergency purposes, without a number of measures in place – I call it ‘fuel husbandry’.
Diesel blends with a bio-diesel content, such as the EN590 spec that is used commonly around Europe and has bio content up to 7%, can be stored up to 12 months without significant deterioration. Although the fuel can start to oxidise and break down before 12 months if conditions aren’t quite right, for example the presence of free water in a fuel storage tank can accelerate the oxidation process. Where blends with a higher bio content are being stored, B20 for example that’s becoming more common in mainland Europe, they are more unstable and therefore the fuel starts to deteriorate more quickly. I wouldn’t want to store B20 for longer than 6 months without taking some precautions.
We are working with a number of companies and organisations storing fuel for ‘emergency’ purposes, usually for backup generators in hospitals, data centres, prisons etc. We recommend the following.
1) Introduce a fuel sampling and testing regime. Test for water content, microbial contamination (aka diesel bug), particle count. Store the data, track it and trend it to highlight potential problems.
2) Install an ‘on tank’ fuel polishing unit to constantly recirculate and polish the fuel – ‘fuel polishing’ is a fancy way of saying ‘filter’. The units are essentially kidney loop systems that remove water and particle contamination.
3) Consider the use of a stability additive. This acts as an antioxidant and inhibits the process that causes fuel to break down.
4) Consider the use of a fuel biocide for prevent microbial growth. This is really ‘belt and braces’, if there is no free water in the tank then there should be no microbial growth.
We should recognise that there is still plenty of high sulphur fuel still in storage that has no bio diesel content, this fuel is relatively very stable. Whilst it’s our understanding that it’s still legal to use, it does, of course come with the downside of high sulphur emissions. As this fuel is used up and is replaced with fuel with a bio content, we expect to see incidences of fuel breakdown and contamination rise.
I hope this is of some use to you, please advise if you have further questions. I’ll be delighted to help.
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