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Diesel Fuel Polishing

Your generator is only as reliable as the fuel sitting in the tank.

The problem with stored fuel

The diesel in your tank might have been bought three years ago.

It has been sitting there ever since, slowly going off, while everyone assumes it is fine because the tank is full.

Diesel does not keep. Left in storage it separates, absorbs water out of the air, grows bacteria and fungus, and forms sludge that settles on the bottom of the tank. Then the day comes when the generator needs to run for eight hours straight, it draws hard from the bottom of that tank, and the filters block.

Fuel-related failures are one of the most common reasons a standby generator dies during an outage. They are also one of the easiest to prevent.

At a glance
What goes wrong in a storage tank

Four things happening right now

Water

Tanks breathe as the temperature changes. Warm damp air comes in, cools, and condenses on the inside walls. Water is heavier than diesel so it collects at the bottom — exactly where the fuel pickup is.

Microbial growth

Where water and diesel meet, bacteria and fungus grow. The result is a dark slime, often called diesel bug, that clogs filters and eats away at the tank.

Sludge and asphaltenes

Diesel oxidises as it ages and forms heavy sticky deposits. Today’s low-sulphur diesel and biodiesel blends are more prone to this than older fuel was.

Rust and debris

Steel tanks corrode from the inside once water is present, and the rust ends up in the fuel.

What fuel polishing involves

Six steps, all carried out on site

01

Sample and test first

We check the condition of the fuel before recommending anything, so you are not paying for a service you do not need.

02

Water removal

Separated out of the fuel and taken away.

03

Particulate filtration

Staged filtration removes sludge, rust and biological matter down to fine tolerances.

04

Tank cleaning

We draw from the bottom of the tank, where the trouble lives, rather than skimming the clean fuel off the top.

05

Treatment where needed

Biocide or stabiliser, if the test results call for it.

06

Report

Before and after condition, in writing, for your maintenance record.

Signs your fuel needs attention

Six things worth acting on

None of these need a technician to spot. If any of them sound familiar, the fuel is the first place to look.

How often?

Test annually, polish when the results say to

Most standby systems

Test the fuel annually

Low turnover tanks

Outdoor tanks and slow burners, more often

History of water

Anything with a water problem, more often

Common questions

Straight answers

Is this cheaper than replacing the fuel?

Usually, yes — and considerably less disruptive. Disposing of a few thousand litres of contaminated diesel is expensive and slow.

Do we need to shut anything down?

No. Polishing is done with the system in place and your generator still available.

How do I know if I need it?

Have the fuel tested. If it comes back clean, you have peace of mind and we will tell you to leave it alone.

Do you polish fuel for generators you do not maintain?

Yes. Fuel testing and polishing are available as standalone services.

Keep reading

Related services

Fluid Analysis

Lab testing of fuel, oil and coolant — this is what tells us whether the tank needs polishing.

Load Testing

The test that draws hard from the bottom of the tank, where the trouble lives.

General Repairs

Tank issues, level senders, day tanks, transfer pumps and containment.

Talk to GenWorx

Book a fuel test

A sample, a lab result and an honest answer. If the fuel is clean we will tell you to leave it alone.