Back-up generators could fail if your stored fuel is not optimally maintained, and fuel polishing is the solution, says Richard Massara.
04 December 2018 | Richard Massara
Stored fuel oil - otherwise known as gas oil or diesel - faces many threats, but five major concerns are:
- Bacterial infection;
- Sediment; and Foreign bodies.
The trouble with water Engines compress fuel and spray it to be combusted, but if there is water in the fuel, it cannot be compressed to the same level.
This makes water dangerous to generators (or any diesel/fuel oil system) as something must give and it is normally the injector that is producing the spray pattern. The worst-case scenario is that the engine will require rebuilding.
Water is also a breeding ground for bacteria. The bacteria will already be in the fuel but will not germinate without the right conditions: a food source (the fuel's hydrocarbons), the right temperature/climate (10-40 °C), and a place to live (the water-fuel interface).
Sludge, sediment and foreign bodies
Black or dark brown spots of sludge in your fuel or your fuel filters are signs of a bacterial contamination in your tank.
However, sludge is really a biomass and not the infection itself, it is only the by-product. The infection can be root-like, plant-like or even a clear jelly-like substance. Bacterial test kits exist to check the fuel, however, you must take a fuel sample near the bottom of the tank as that is where the infection will grow.
Sediment in the fuel is formed in different ways. This fine, sand-like build-up can be a factor of the fuel degrading, it can be caused by fuel oxidisation (often as a factor of fuel contact with an incompatible material such as brass), or even by the addition of fuel additives.
Stronger doses of additives can oxidise the fuel and cause degradation, forming sediment as a by-product.
Foreign matter can cover anything from atmospheric dust to poor-quality fuel to items dropped or pushed into fuel tanks. It can cause filter clogging; and even worse, chemically react with the fuel to form acids or gums.
Why bother cleaning it?
Dirty fuel can lead to inefficiency, reduced power, and more emissions. Worse, you may see brown-outs/black-outs caused by fuel starvation/blocked fuel filters, or generator engine damage caused by water, leading to a complete generator failure, a high repair bill and, of course, no power.
By the time the in-line fuel filters start to take out this contamination, it will have built up a large layer in your tank bottom. This traps the poor-quality fuel, but also breeds more contamination. This lower section must be removed before you can consider cleaning the rest of the tank.
How to polish fuel
Fuel polishing is the automated process of fuel cleaning by recirculation of the fuel. Where traditional cleaning can only take place by in-line filters, operating when the engine or transfer pumps are firing, fuel polishing is a self-controlling, self-pumping, self-monitoring multi-stage filtration process, which removes the fuel from the lower sump level (bottom of the tank), cleans it and then returns the same fuel to the tank top.
This is independent of the generator's pipework so will not interfere and can be run autonomously to clean and maintain fuel.
Drawing from the tank's lowest point removes the worst fuel contamination first, but the process continues working through the entire tank content.
It can be repeated every few days, weeks or months depending on the fuel condition and the level of power support needed.
A fuel polishing system is also a data recording device and monitors performance, contamination build-up or service requirements.
Over time, this builds a picture of your fuel quality.
If you drained water once last year, but three times this year you either have a leak, water ingress or a poor-quality supplier. The polishing system has removed the threat, and the data alone can save you thousands.
Richard Massara is technical sales manager at WASP Pure Fuel Systems