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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.

How Filter Media Collects Particles

The Filter Guys

How Filter Media Collects Particles. There are four basic ways media captures particles.

The first, called inertia, works on large, heavy particles suspended in the flow stream. These particles are heavier than the fluid surrounding them. As the fluid changes direction to enter the fiber space, the particle continues in a straight line and collides with the media fibers where it is trapped and held.

The second way media can capture particles is by diffusion. Diffusion works on the smallest particles. Small particles are not held in place by the viscous fluid and diffuse within the flow stream. As the particles traverse the flow stream, they collide with the fiber and are collected.

The third method of particle entrapment is call interception. Direct interception works on particles in the mid-range size that are not quite large enough to have inertia and not small enough to diffuse within the flow stream. These mid-sized particles follow the flow stream as it bends through the fiber spaces. Particles are intercepted or captured when they touch a fiber.

The fourth method of capture is called sieving and is the most common mechanism in hydraulic filtration. As shown at right, this is when the particle is too large to fit between the fiber spaces.

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.