Foam Filter: The Complete Guide

Foam filters are air cleaners used to trap undesired pollutants and particles.

They use foam as the filtering material.

They are made of interlocking cells to prevent the passage of dust particles.

Foam materials are excellent for many filtration applications.

In this guide, you will find all information you’re looking for about foam filters.

Let’s dive right in.

Benefits Of Foam Filters

 A Foam Filter

A Foam Filter

  1. They are soundproof
  2. Excellent impurities retention rate making them ideal for suction and exhaust filters.
  • They are water-resistant or non-absorbent: they can allow water to pass through without being blocked or clogged.

This allows them to be used even in applications that use liquids.

  1. They are easy maintenance
  2. Foam filters have excellent durability
  3. UL and ULC listed
  • Foam filters have excellent dust absorption capabilities.
  • They are oil and contaminant resistant
  1. They are chemical resistant
  2. They are flame retardant
  3. Have excellent porosity to air making them ideal for improving engine performance and fuel usage.
  • They are reusable thus cost-effective and eco-friendly.

Foam Filters Are Reusable Thus Ecofriendly

 Foam Filters Are Reusable Thus Eco Friendly

Where To Use Foam Filters

Foam filters are used in various fields such as chemistry, treatment of sewage and petroleum, decorations, motor industries and medical facilities.

Filter Applications:

Small engines, air conditioning, ventilation systems, dehumidifier, air intakes, heating systems

An Engine Filter

An Engine Filter

Coalescing:

Separation of water from gasoline, perchloroethylene and jet fuel.

 Coalescing Cube Made From Foam Filters

Coalescing Cube Made From Foam Filter

Noise Suppression:

Microwave covers, aircraft, industrial vacuum cleaners, high-intensity sounds.

Acoustic Foam Suitable For Music Studios

Acoustic Foam Suitable For Music Studios

Miscellaneous

Floor scrubbing pads, hydraulic line filters, paintbrush applications, powder puffs, blackboard erasers

Powder Puffs Made From Foam Filters

Powder Puffs Made From Foam Filters

Best Material For Making Foam Filters

The best material for making foam filters is polyurethane.

It has its advantages to filtration, such as;

  1. It is durable.
  2. It can be used in soundproofing applications
  • Excellent impurities retention rate making them ideal for suction and exhaust filters.
  1. It is water-resistant or non-absorbent: it can allow water to pass through without being blocked or clogged.

This allows them to be used even in applications that use liquids.

  1. It is easy maintenance
  2. It has excellent dust absorption capabilities.
  • It is oil, chemical and contaminant resistant
  • They are flame retardant
  1. Have excellent porosity to air making them ideal for improving engine performance and fuel usage.
  2. They are reusable thus cost-effective and eco-friendly.

Polyurethane Foam Filters

Polyuretahne Foam Filters

How To Choose Best Material For Foam Filters

You should consider the porosity

The filter size should fit the application

The fibre size should improve the filtration of the foam filter.

They should be durable

Also, they should be light in weight

They should require little to no maintenance

Should easy to replace and repair.

The pore density should match the system of application’s need.

Should be available in different densities (PPI) and thickness

Should be available in sheets, pre-cut pieces and rolls

Should be washable in warm water

Should be a combination of different materials such as aluminium mesh, steel mesh, electrostatic mesh, activated carbon

Limitations Of Foam Filters

  • Unrestricted airflow makes filtration sound louder than normal.

Increased air intake by engines, makes them roar louder than normal despite the performance improvement.

  • Increased engine exposure to dust.

High-performance filters may expose car engines to more dust particles due to increased air intake.

It may also result in wear and tear of the filtration and thereafter the damage of the engine’s internal parts.

  • Water can soak the filter and get to the engine.

For automobile applications, dirty water on the roads can pass through the filters.

The mud and dirt in the water can soak the filter preventing sufficient air circulation.

  • Foam filters are expensive to purchase as compared to other types of filters like paper filters.

How To Determine Dirt Holding Capacity Of Foam Filter

Dirt holding capacity is also referred to as test dust capacity.

It is the quantity of synthetic dust that can be retained by the filter before the final specified pressure drop increases.

Dirt holding capacity serves as an indicator of the filters shelf life.

Filters with higher dust holding capacities last longer.

The comparison of dirt holding capacity of different filters can only be effective subjected under

  • Same test dust
  • Same procedures of testing
  • Same rate of airflow
  • Same set final pressure drop.

The difference in these parameters explains the comparison.

There are two types of commonly used testing procedures; EN 779 AND ISO 16890.

They use different test dust to conduct their tests.

Test standardEN 779ISO 16890
Test dustL1 (ASHRAE) test dustL2 (ISO Fine) test dust
Final pressure drops250 Pa for coarse dust filter200 Pa for ISO coarse filter
450 Pa for medium and fine dust filters300 Pa for ISO ePM10 ePM2.5 and ePM1

From the two procedures, one type of filter can have two different dust holding capacities.

A good example is the MPK 48-20 GT compact filter.

Filter TypeMPK 48-20 GTMPK 48-20 GT
Test standardEN 779 ISO 16890
Dust Holding Capacity470 g600 g
Test dustASHRAEISO Fine
Air flow rate3400m3/h3400m3/h
Final pressure drop450 Pa300 Pa

Important Features To Look For In Foam Filter

  • Flexible: the foam filters should be flexible enough to fit in their area of application.
  • Open pores density: the number of pores per inch should match the filter’s use.

The higher the number of pores per inch, the finer the particles that are to be filtered.

  • A high degree of permeability: filters should be able to allow the media of application to flow with ease.

When the media of application, say air or liquid, flows through the filters easily, the filtration is high.

  • Dirt holding capacity; is the amount of dust a filter can hold from installation to replacement, repair or service.

The more dust it can hold, the better the filter.

  • Washability: the filters should be washable in water.

This reduces the cost of replacement and improves the useful life of the foam filter.

  • High tensile strength: this is due to the precise size of the homogenous cells in foam filters.
  • Temperature resistance: foam filter should be able to resist high temperatures and prevent thermal oxidation.
  • UV and light-resistant: foam filters should be able to resist UV and light effects.

They should also be resistant to ageing.

  • Oil, chemical and contaminant resistance:

In applications where oils, chemicals or contaminants are being filtered, the foam filters should be able to stand the test.

  • Reusability: the foam filters should be to be reused after washing or most repair applications.
  • Non-allergic and non-toxic: filters are fabricated to be harmful to users during repair, replacement of cleaning.

How Foam Filter Works

The Cells In A Foam Allows For Air Circulation Hence Used In Aquarium

The Cells In A Foam Allows For Air Circulation Hence Used In Aquarium

Foam filters use foam as a medium of filtration.

The foam used in filters is polyurethane.

They are composed of tiny interlocking cells.

The cells trap and distribute dust particles across the whole volume of the foam filter.

This is due to the pore size that allows air to flow through unrestrictedly while preventing particles from passing.

Retentive additives are sometimes added to improve the levels of filtration without obstructing airflow.

Ideal filters will give maximum resistance to prevent the passing of contaminants.

They will also give minimum resistance to system fluid flow.

Filter media are made from porous materials that have pores and capillaries.

The capillaries allow the flow of system fluid while pores restrict dust particles.

The particles are transported throughout the media through different mechanisms.

The dominant mechanism of transportation varies from one filtration circumstance to another.

  1. Direct interception: the particles follow the streamline of the fluid without deviation.

Particles are captured when they come close to the particle radius of the fibre.

  1. Inertial impaction: particles deviate from the system fluid streamline.

Particles are “thrown” within the retention site for capture.

  • Brownian diffusion: small particles experience the Brownian motion.

Particles diffuse in the fibre matrix.

Smaller particles increase the Brownian effect while it reduces with higher velocities.

  1. Gravity: the gravitational pull on heavier particles, deviates them from the fluid streamline.

Heavier particles increase the gravity while high velocities and viscosities reduce the effects.

  1. Hydrodynamic effects: it occurs due to the particles being nonuniform across the flow field.

The effects deviate particles to possible retention sites.

Most particles are of irregular shapes.

  1. Electrostatic attraction: the charges of the particles and fibre differ.

The difference makes particles to be attracted to the fibre surfaces.

It is highly effective at low fluid flow velocities.

Dominant mechanism Of Particle Transportation Within The Foam Filter

Dominant Mechanism Of Particle Transportation Within Foams

How To Determine When To Replace Foam Filter

Various determinants indicate the need to replace foam filters.

Looking at automobile engines as an example, several signs indicate the need to change filters;

Reduced Economy On Fuel Consumption

The car engine will always consume more fuel to compensate for oxygen reduction.

This is to enable the engine to produce enough power for the car.

Reduction of gas mileage is a clear indication that the filters need replacement.

It affects old models of cars that have carburettors to mix fuel and air.

This, however, has little impact on more cars with fuel-injection engines.

Fuel-injection systems calculate the quantity of air that goes to the engine.

Dirty Spark Plug

Incomplete combustion may result in sooty black flame from the engine.

The sooty is at times deposited on the spark plug leaving some sooty marks.

The soot is a result of the lack of enough air in the fuel-air mixture.

This may be due to the blockage of filters.

Strange Sounds From The Engine

Under normal circumstances, smooth engine rotations are sensed as subtle vibrations when the car is stationary.

Excessive vibration, popping noises or hearing of coughing sounds indicate problems with the filter.

The unusual sounds and vibrations are likely to originate from the clogged air filters.

This damages or dirties the spark plug.

Engine Light Illumination

Modern automobile engines consume 10,000 gallons of air for one gallon of fuel used through complete combustion.

Carbon deposits may be formed as a result of an inadequate supply of air.

The accumulation of such deposits sets of the engine light in vehicles.

Upon comprehensive analysis and troubleshooting, inadequate oxygen is the leading cause of such deposits.

Dirty Air Filters

Sometimes you will need to check your car’s air filters.

New air filters are always white.

The presence of dust is an indication that there is a need for replacement.

Horsepower Reduction

Prolong use of a car, makes you get a feel of its normal operating standards.

When the car fails to respond to throttling as it always does, the engine does not receive enough air as it used to.

Clogged air filters could be the cause of this.

Replacing the air filter can increase the engine performance by around 11%.

Sooty Exhaust

When there is not enough air, some fuel undergoes incomplete combustion.

Such fuels come out as very dark fumes or black smoke from the exhaust.

You might also hear some popping noise as a result of heating or igniting unburnt gasoline in the exhaust pipes.

Sooty smoke is a clear sign that the air filters require replacement.

The Presence Of Fuel Smell During Engine Start

Insufficient oxygen in the fuel injection system results in unburnt fuels leaving through the exhaust.

Instead of smoke, the smell of the fuel will come through the exhaust.

Misfiring Engine

Misfiring is caused by improper mixing of air and fuel.

Insufficient air supply increases the fuel quantity in the fuel-air mixture.

Also, the unburnt fuels from the engine come out as soot residues.

The soot will accumulate on the spark plug over time.

This prevents the spark plugs from sparking the mixture effectively.

The engine will then misfire under such circumstances.

Replacing the air filters will be a great solution to misfiring problems.

From the above signs, inefficiencies in are of applications are likely to be caused by filter related problems.

It is advisable to check the filtration system first in case problems arise in the area of application.

A regular filter change ensures the prolonged life of the system of application.

The change in filters result in;

  • Lower emissions from the system make it environmentally friendly.
  • Longer engine life
  • Lower cost of operation.
  • Lower power demands or fuel consumption.

How To Check Quality Of Foam Filter

There are several methods of testing the quality of foam filters.

The tests check on;

  • Collapse strength
  • Burst pressure
  • Single-pass efficiency
  • Multiple pass efficiency
  • Dirt holding capacity
  • Pressure flow profile
  • Impulse fatigue
  • Durability
  • Vibration
  • Bubble point
  • The integrity of design and fabrication

The ISO and SAE have different ways of conducting these tests.

The most common are the SAE HS 806 and the SAE J1858.

These tests include;

  1. Resistance to flow
  2. Media migration test
  • Ability to meet the set environmental conditions
  1. Mechanical test
  2. Collapse test
  3. Installation and removal
  • Particle retention test
  • Filter capacity test
  1. contaminants removal test

When selecting quality filters, it is wise to consider;

  1. The size and efficiency of capture

SAE HS 806 is focused on the performance of filters.

They consider the weight of the contaminant and not hr size of the dust particles.

  1. The dirt-holding capacity of the foam filter

This reveals how long the filter can be in useful service life before reverting to bypass.

  1. Flow profile for pressure.
  2. The material used in the construction of the filter.

Quality Certifications Foam Filters Should Comply With

  1. Restriction of Hazardous Substances (RoHS) certification for directives on banned substances.
  2. UL 94 HF-1 and UL 900

Filters must be flame retardant.

  • FMVSS 302

The certification is based on the burning behaviour of the filters during the useful life.

It helps to reduce the death rates and the number of injuries to occupants in case of fires.

They should also meet the strict requirements on fire safety set up by rail and aircraft authorities.

  1. ISO 9001 certification for quality management systems.
  2. ISO 14001 certification for environmental management.
  3. ISO 450001 certification for occupational health and safety management
  • ISO 16890 certification for dust holding capacity
  • REACH certification
  1. Ingress Protection (IP) certification.

The IP scale must confer with IEC standard 60529 to explain the level of contaminant protection of the filters.

The IP rating is used to specify and test filters on the environmental and operating conditions.

  1. MIL-STD certification

The filters must be designed for a specific environment.

It must be tested to understand the limits of the conditions it can withstand during its service life.

Recommended Dimensions Of Foam Filters

The standard dimensions for foam filter are;

  1. 72 inches by 48 inches
  2. 36 inches by 48 inches

The height of the filters varies depending on the area of application.

Some standard heights are; ¼, ½, ¾, 1, 1½, and 2 inches.

The pore size of filters varies depending on the particle sizes being filtered.

Open-cell foam filters have minimal air restriction.

Fine porosity filters, on the other hand, have high filtration levels.

The sizes are also determined by the intensity of the system where the filters are used.

Factors Causing Deterioration Of Foam Filter?

The ideal storage for foam filters is a cool, dry and dark environment.

Changes in any of the ideal conditions result in wear of the filter.

They will lose their efficiency in the long run.

Several factors might result in degradation of filters, such as;

  • Exposure to solvents and sulphates such as engine exhaust fumes.
  • Prolonged high-temperature exposure.

Foam filters can stay longer in place with a temperature range of 40 F to 90F.

Exposure to environments beyond this range increases the rate of degradation of filters.

  • Lengthy operation in areas with high humidity.

The acceptable humidity of the environment should be between 40% and 80% relative humidity.

  • Exposure to UV light.

The filter should be covered with dark plastic material.

It helps to protect the filters from UV light as well as keep them dry.

  • Filters also degrade due to storage time.

Longer storage periods beyond seven months or one year degrades the usefulness of the filter.

You should purchase cost-effective quantities.

They should also be just enough for a few months’ use.

How Did Paper Filters Compare To Foam Filters?

Foam filters have a higher quality than paper filters.

They deliver great performance by filtering more particles from the air.

Foam filters can be washed while paper filters cannot.

Besides, foam filters last longer than papers filters.

Paper filters are not as sturdy as foam filters.

Paper filters are also not as breathable as foam filters hence a limited number of applications.

Paper filters require replacement more often than foam type.

This makes them expensive in the long term due to frequent replacement.

 A Paper Filter

A Paper Filter

How To Determine Efficiency Of Foam Filters

You can determine the efficiency of foam filters by feeding a mixture of air and standard test dust of known concentration.

This is done until the end of the filter life is reached.

This is when the dust restriction reaches the designed level.

Standard test dust represents;

  • Consistency
  • Dust particle size range in real conditions.

When the end of life of the filter is reached, the weight of the dust accumulated in the filter represents the capacity of the filter.

Dust that will pass the filter during the test will be captured by the absolute filter downstream.

The difference in the weights of the filter capacity and that captured in the absolute filter is the efficiency of the filter when expressed as a percentage.

The efficiency of foam filters increases with an increase in the number of dust particles accumulating on the filter.

Filters that are close to their end life will work better than those that are changed.

How Much Foam Filters Cost?

The cost of foam filters varies depending on the size of the filter required.

For most vendors, buying more filters reduces the price per filter.

In other manufacturers, buying more filters comes with free shipment.

Recommended Pore Size Of Foam Filters

The foam filters are available in a variety of pores per inch (PPI).

Also, they range from 10 PPI to 60 PPI.

The most common foam filters have a 20 PPI foam density.

They are critical in applications that require large pores for filtration such as gutters and ponds.

For any questions or inquiry about foam filters, contact us now.

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