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Pre-line Fuel Filtration Housing.

The Filter Guys

Today, diesel vehicles are fitted with the latest high performance fuel injection systems. As a result, fuel filtration must meet far more demanding requirements. Pre-Line is a universal and practical pre-filter system, based on the spin-on filter concept, which provides an ideal, cost-saving retrofit solution.

Features and advantages

  • Use with diesel fuel DIN ISO 590 (5% FAME), DIN 51 628 (7% FAME)
  • Up to 600 l/h volume flow rate
  • Use of multigrade high performance media
  • 93% water separation
  • Modular system with excellent flexibility
  • Easy to service
  • Integrated, effective and easy to handle hand pump with 45 degree position to drain off water and for priming during service
  • Integrated water collector
  • Parallel operation possible with a number of systems

These filter housings from Mann Filter are available from Sterling Filtration Ltd.


How Filter Media Functions In a Filtration System

The Filter Guys

How Filter Media Functions. The job of the media is to capture particles and allow the fluid to flow through. For fluid to pass through, the media must have holes or channels to direct the fluid flow and allow it to pass. That’s why filter media is a porous mat of fibers that alters the fluid flow stream by causing fluid to twist, turn and accelerate during passage.

The fluid changes direction as it comes into contact with the media fibers, as illustrated above. As the fluid flows through the media, it changes direction continuously as it works its way through the maze of media fibers. As it works its way through the depths of the layers of fibers, the fluid becomes cleaner and cleaner. Generally, the thicker the media, the greater the dirt-holding capacity it has.

Looking at a cross-section view of the fibers:

we can see how the flow stream is accelerated as it flows into the spaces between the fibers.

This is applies to all liquid filters, be they oil, fuel, water of water glycol. For more information on filtration products and replacement elements please contact us for a chat. We’re here to help.

Where Contamination Comes From.

The Filter Guys

Where Contamination Comes From.

New Hydraulic Fluid

Adding new fluid can be a source; even though it’s fresh from the drum, new hydraulic fluid isn’t clean. (It may look clean, but, remember, the human eye can only see a particle the size of about 40 μm.) Oil out of shipping containers is usually contaminated to a level above what is acceptable for most hydraulic systems: typically, new fluid has a cleanliness level about the same as ISO Code 23/21/19, and water content is typically 200 to 300 ppm. Never assume your oil is clean until it has been filtered. One very effective way of ensuring thorough fluid conditioning is with a dedicated off-line circulation loop, or “kidney” loop filtration.


Built-in contamination, also called primary contamination, is caused during the manufacture, assembly and testing of hydraulic components. Metal filings, small burrs, pieces of Teflon tape, sand and other contaminants are routinely found in initial clean up filtration of newly manufactured systems.


Ingressed or external contamination comes from the environment surrounding the system. Dirt can enter the hydraulic fluid supply through leaking seals, reservoir breather caps, and worn cylinder rod seals. Ingressed moisture, particularly, can cause long-term problems. As a hot system cools at night, cool moisture-laden air can be drawn into the reservoir; as the air condenses, water is released into the reservoir. Water in excess of 0.5% by volume in a hydrocarbon-based fluid accelerates the formation of acids, sludge and oxidation that can attack internal components, cause rust, and adversely affect lubrication properties. The severity of ingression and type of contaminant are dictated by the applications and environment.


Maintenance procedures can introduce contamination into the system. Opening the system allows airborne particles to enter. Leaving the system open during operation provides continuous ambient particle ingression. Keep your system closed as much as possible.


The major source of contamination are the pump and actuators, the hydraulic cylinder, or the hydraulic motor. Wear-generated contaminants are a hazard during normal hydraulic system operation. The circuit actually generates additional particles as the fluid comes into contact with the precision machined surfaces of valves, motors and pumps. Contaminant levels can keep doubling with every new particle generated. The result can be catastrophic if these contaminants are not properly filtered out of the system.

Rubber & Elastomers

Due to temperature, time, and high-velocity fluid streams, rubber compounds and elastomers degrade—thus releasing particulates into the fluid. This may be from hoses, accumulator bladders, seals, or other elastomer products.

High Water Based Fluids

The water in HWBF tends to support biological growth and generate organic contamination and microbes.

Replacement of Failed Components

Failure to thoroughly clean fluid conductor lines after replacing a failed hydraulic pump will cause premature catastrophic failure. Donaldson recommends frequent oil sampling to ensure proper contamination control. Sample test points should be close to hydraulic pumps and at other key locations that provide safe, reliable access to the fluid while under full system pressure.

Spark Arrestors

The Filter Guys

The general rule with spark arrestors is if it will fit on the exhaust pipe of an engine, it will also have an acceptable back pressure for that engine. In some cases, a larger size spark arrestor will be required to stay within backpressure limits, and in those cases adapters will have to be used.


The spark arrestor should be inspected and cleaned out every 1,000 operating hours or three times per season. Visually inspect for holes, cracks and metal corrosion. Check the mounting clamp to make sure the spark arrestor is securely mounted. Replace the spark arrestor if your inspection reveals any of the above unsafe conditions.


  • US Forest Service approved
  • Reduced fire hazard – 95% or greater efficiency on incendiary sparks
  • Centrifugal force separates solids from exhaust gas
  • Aluminized steel with stainless steel critical parts
  • Can be installed vertically or horizontally (If possible, the clean out should face away from all fuel tanks, the vehicle operator’s position and the air cleaner inlet.)

All of the above spark arrestors are available from Sterling Filtration Ltd. Give us a call on 01902 491118 for a competitive quote.