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How PM&I Can Help Prevent Delays

How To Purify Fuel

High Speed Centrifuge and

Filter, Separator, Coalescer Fuel Purification

how to purify diesel fuel

Steps to Conduct a Visual Fuel Inspection:

Your fuel should be "clear and bright" meaning absent of water and particles.
Clear of particles floating in the fuel. Bright and not cloudy. A cloudy white mist in fuel indicates a presence of water.

First, let the sample settle for some time. This will allow any air bubbles in the fuel sample to make their way out and allow particles to float down to the bottom of the sample jar.

Next, check carefully (especially at the bottom of the sample) for particles. Be sure to look closely.

Cloudy or milky fuel indicates suspended water.

The particles in your fuel can be dirt or they can be micro-organisms that are present in your fuel supply or growing in your fuel tanks.

Use a fuel additive to kill micro organisms living in your fuel tanks.

You should send a fuel sample to a lab for outside tests to truly know what is in your fuel.

When you purify your fuel you should use a method that will remove both the particles and the water from the fuel.

Consequences of Using Dirty or Wet Fuel:

engine failure

poor engine performance including increased emissions

increased maintenance cycle

shortened engine life.

There are 2 ways to purify fuel:

Centrifugal Separation

Centrifugal Force Removes both Water and Particles from Fuel

No elements to replace. Expensive parts and maintenance on occasion.

Cleanliness output not as effective as the Filter, Separator, Coalescer method.

Filter, Separator, Coalescer Fuel Purification

Filter: Passing the Fuel Through a Media - Removes Particles

Separator: Passing the Fuel Through a Media - Removes Water

Coalescer: Mechanically Separates Water From Fuel - Removes Water

No moving parts except pump and motor. Elements to replace occasionally depending on incoming fuel quality.

Better fuel output cleanliness than a centrifuge. Better for newer Tier III and better engines.

What you need to know:

How much fuel you need to purify (gallons or liters per minute).

Pressure of the fuel (if pressurized line as opposed to a tank)

Temperature of the fuel.

Where are you going to purify the fuel: Incoming fuel supply, recirculate storage or day tank(s) or on engine.

Engines all have an on engine fuel filter but many people like to add a pre filter on engine.

The amount of fuel you need to purify is determined by your fuel supply set up:

- Flow rate of fuel entering engine (purification in line with fuel supply to engine such as boat and workboat applications)

- Flow rate of all engines combined (if using one purification method for all engines / fuel tanks)

- Flow rate of fuel transfer pump (purification method inline with fuel tank refill)

- Maximum time required to purify your fuel tank (purification of your fuel tank prior to or during use)

Diesel Fuel Purification - Spin On Series

15 to 120 Gallons Per Hour

10 Micron Filtration

On engine pre filter. In fuel line before engine filter.

Most applications out there (smaller size engines and generators) will use a Spin On Filter that will remove both water and particles. This filter is meant to be put in-line with your fuel system on the suction side of the fuel pump. It can be put on the discharge side of the fuel pump with certain limitations. Included with the filter is a mounting bracket. Replacement elements can be purchased as needed. Be sure to keep additional elements on hand. If your engine has its own fuel filter keep it in place. Many fuel systems have multiple filters on them.

Spin on filters come 10 micron size. This means that any particle less then 10 microns in size will be able to pass thru the filter. If you have multiple filters in place you want the filtration to increase (smaller micron) as you approach the engine (30 micron then 10 micron then 2 micron). If you have a fuel filter on your engine most likely it will be in the 2 micron range as it is the last filter prior to the fuel entering the engine.

Diesel Fuel Purification - Turbine Series

60 to 540 Gallons Per Hour

2, 10 or 30 Micron Filtration

On engine pre filter. In fuel line before engine filter.

The turbine series diesel fuel purification system cleans your fuel by separation, coalescing and filtration.

Separation: The turbine centrifuge separates solids and ’free’ water through centrifugal action. Although the turbine has no moving parts, over 30% of the contaminants are removed here.

Coalescing: Smaller water droplets and solids coalesce on the specially designed conical baffle and fall to the collection bowl.

Filtration: Engines benefit from near 100% water separation and fuel filtration with a water repelling media.

Similar to the Spin On Series, these units are designed for installation on the suction (vacuum) side of the fuel transfer pump for best efficiency but may be installed on the pressure side (up to 15 psi).

Replaceable cartridge elements stop water and remove solid contamination and are available in 2, 10 or 30 micron. Engine owners can specify their filtration needs based on application, fuel quality, operating climates and maintenance schedules. A 30 micron filter (or primary filter) is used to filter raw fuel (or poor quality fuel) before it can be further filtered by finer medias such as a 10 or 2 micron. A 10 micron filter (or secondary and even final) is used to filter fuel which is known to be of good quality. A 2 micron filter (or final filter) is the finest filtration available and is the last filter used prior to engine ingestion. A simple rule to remember is the finer the filtration, the more frequent the filter change. (Carry extra filters on board). If your engine has its own fuel filter, keep it in place. Most likely it is in the 2 micron range.

Diesel Fuel Purification Centrifugal Series

238 Gallons Per Hour and Larger

Manual or Automatic Cleaning

Cross connect storage and day tanks so one unit can purify all tanks.

No elements to replace. High cost parts and maintenance.

Not good enough cleanliness output for newer Tier III engine use.

High speed vertical centrifugal purifiers remove both water and particles with a centrifugal action.
See the article: How Does A Centrifuge Work? for more information on this purification process.
This type machine is for larger boats and ships. It can be used to purify both fuel or oil.

- Fuel purification during tank refill process

- Fuel purification of idle / off line fuel tank

- Fuel purification of online fuel tank

- Fuel purification of several tanks using cross connect piping (purifying a single tank at a time)

The simplest of these machines require the bowl to be cleaned periodically (depending on fuel quality). The more expensive and complex machines have a self cleaning feature. These machines have unlimited capacity as they can be placed in parallel to increase performance.