Coalescing filtration is the process of separating two phases of matter in fluid stream using a coalescing filter.

For instance, you can separate water droplets and aerosols from gas through coalescing filtration process.

With the help of the coalescing filter element, you can allow the air with the liquid contaminants to pass through.

As it goes through the element, there are numerous filtration media that is capable of trapping the liquid aerosol and droplets.

This will allow the dry and clean compressed air to come out of the coalescing filter through the outlet.

The type of contaminants that you can eliminate using the coalescing filter will depend on the phase of separation.

Gas phase separation using the coalescing filter gets rid of oil mist or moisture from airstreams that are contaminated.

Here are some of the gas phase separations that you can perform using a coalescing filter.

• Separation of liquid moisture from a moisture laden stream of air.
• Separation of oil mists from a stream of air.

You can also use the coalescing filter in the liquid phase of separation to get rid of contaminants.

Here are some of the separations that you can perform within the liquid phase separation.

• Elimination of moisture particles from different organic streams such as removal of moisture from fuel pipeline stream.
• Elimination of liquid organic contaminants from a stream of water such as the cleaning of oily water streams.

Particulate filtration and coalescing filtration are two types of methods for the elimination of different contaminants from different fluid types.

Here is a comparison between the two type of filtration.

· Particulate Filtration

Particulate filtration

Particulate filtration is the process where you will use a particulate filter to eliminate solid particles from a liquid or gas.

A particulate filter is a device with different types of filtration media that will trap solid particles from liquids and gases.

The gas or liquid will flow from the outside through the inlet and the filter elements thus maximizing the service life.

The size of solid particles that you will trap using the particulate filter will depend on the size or grade of the filter element.

· Coalescing Filtration

Coalescing filtration

On the other hand, coalescing filtration involves the use of a coalescing filter in separation of two phases.

For instance, you can use a coalescing filter element in a housing to separate water droplets and aerosols from a gas fluid.

The wet gas will flow through the coalescing filter from the outside through the elements that are inside the housing.

The filtration media within the coalescing filtration elements will capture the liquid contaminants and allow dry gas to pass through.

After using the coalescing for a very long time, you will note that there are numerous problems associated with it.

Well, this can be due to blockage of the system pores by too many contaminants on the filter element.

On the other hand, it can be due to the fact that the coalescing filter is old and cannot work well anymore.

This leads to an increase in the differential pressure within the coalescing filter elements.

Apart from that, you will realize that the gas does not flow at the usual velocity and if it does, it comes with the contaminants.

You may decide to clean it up and use it for a while longer to eliminate the contaminants.

In any case the problem persists, you will have to do a proper replacement of the coalescing filters.

You can learn more about filter element replacement.

Coalescing filters use a number of mechanisms in the process of eliminating contaminants from the fluids.

Here are the three main mechanisms that you need to know before purchasing a coalescing filter.

· Diffusion Filtration Mechanism

Diffusion filtration mechanism is the process of removing very small particles from a contaminated fluid.

The particles that you will remove using the diffusion mechanism are usually 0.1 microns in size or even smaller than that.

It involves the motion and collision of particles which will eventually get trapped by the coalescing filter element.

In the long run the contaminants will adhere to the coalescing filter elements and allow the clean fluid to pass through.

As that happens the contaminants will conjoin together and form larger masses that you can easily drain away.

· Direct Impact Filtration Mechanism

You will use the direct impact filtration mechanism to get rid of contaminants that re 1 micron or larger.

This process will also involve the collision of the particles thus making it simpler for the fibers to trap the contaminants.

As air flows through the coalescing filter, it will have to pass through the coalescing filter media before going out.

The coalesced water and oil droplets of the contaminants will form and eventually get trapped on the coalescing filter elements.

In the long run the oil and water droplets will form larger particles and eventually flow downwards and collect in a bowl.

Eventually, the bowl will also fill up with the liquid water and oil contaminants before you drain them out.

The clean air will also move through the elements and then out of the coalescing filters through the outlet.

You can use this filtration mechanism to get rid of contaminants such as rust, dirt and dust particles.

· Interception Filtration Mechanism

You will use the interception filtration mechanism to get rid of contaminants that are 0.1 to 1 micron in size.

This process depends on the turbulent flow which will end up forcing the contaminants against the wall of the fiber.

The filter media f the coalescing filter will eventually end up capturing the minute particles and allowing clean fluid to flow.

The smaller the size of the pores, the higher the efficiency of capturing the contaminants from the flowing fluids.

There are two forms of coalescing media that you can use in the process of eliminating contaminants from different fluids.

Here are the two main forms of coalescing filter media that you can use in different applications.

Coalescing filter element

· Surface Coalescing Media

Surface coalescing media contains highly oleophobic and hydrophobic surfaces that will prevent the contaminants from penetration of the surface.

It can either reject the liquid droplets from the surface or collect the liquid droplets on the surface.

As that continues, the droplets will coalesce with other droplets and form larger liquid droplets.

In the long run, the droplets will be large enough to wash off from the surface or fall by gravitational pull.

In general, this form of coalescing media consists of low energy polymers such as silicone or fluoropolymer.

In case you are using a fibrous filter media, then the surface energy polymer will exist in form of:

1. Fibers
2. Binders
3. Surface Coating

· Depth Coalescing Media

In depth coalescing media, the filter element will filter the contaminants by trapping them within the filter element.

Coalescing will occur when the liquid contaminants in the media combine with other liquid contaminants.

This will happen only if the fibers of the filtration media have larger surface energy.

It usually uses a significant or high percentage of fine fibers including glass microfibers.

The finer the filtration fiber, the more effective it is in the removal of the smaller particle sizes.

Apart from that, you have to make sure that the fiber surface is not too oleophobic (hydrophobic) or hydrophilic.

You must, however, try and maintain it somewhere in between hydrophilic and hydrophobic.

This will ensure that the liquid particles stick to the filtration media and allow coalescing to occur.

In the long run, the liquid particles will coalesce and drain outwards towards the outlet.

Coalescing filter element

You may realize that many companies are now using coalescing filtration technology in most of their applications.

Here are the main benefits that you will enjoy with the application of coalescing technology in your projects.

• You have the ability to customize your own coalescing filter or otherwise upgrade the existing filter.
• Highly efficient type of machine that you can use in the filtration process of different fluids
• Very wide surface area that will lead to lower drop in pressure thus increasing efficiency
• It has various micron ratings that can produce about 99.98% or 99.0% level of efficiency
• Ensures that the downstream equipment in use are safe from dangerous contaminants
• It ensures that it eliminates maximum amount of liquid and solid particles from air or gas processing streams.
• Reduces the expenses on operation and maintenance of gas linked machines
• It has an efficient filtration system that will last longer than usual thus reducing downtime and maintenance cost.

You need to understand the main characteristics of a gas coalescing element filter before you attempt to use it.

Here are the main technical characteristics that you need to pay very close attention to.

Efficiency of the Gas Filtration in Filtering Liquid Drops

You have to make sure that the level of efficiency is high ranging between 95% to 99% depending on filter type.

Efficiency of Filtration of Gas from Liquid and Solid Contaminants

In this case, if the liquid or solid contaminants are of a size larger than1 micron the efficiency must be between 98 to 99%.

Filtration Efficiency of Gas from Solid and Liquid Contaminants

Here, you will consider liquid and solid contaminants that have a size larger than 1 micron.

You will make sure that the efficiency of the coalescing filter ranges between 98% to 99.99%.

Volumetric Efficiency

The machine can handle different gas volumes such as 50 million cubic meters of fluid within a day.

You can also rate it on an hourly basis which can be 250 cubic meters of fluid in an hour.

Residual Volume of Solid and Liquid Particles

After purification of the gas stream, you may expect residues in the gas stream at about 1 milligram per cubic meter or less.

Working Temperature

You should also try and maintain the temperature at between 70 degrees centigrade and 150 degrees centigrade for solid filtration.

For liquid filtration, you will maintain the temperature at between 70 to 90 degrees centigrade.

Just like any other machine, you will note a few limitations of using the coalescing filters.

Here are some of the limitations that might hinder your operations.

• High Cost of purchasing and Installing the coalescing filters forcing you to dig deeper into your pockets.
• Replacing the coalescing filter will also cost you as you need to purchase a new coalescing filter which is costly.
• It depends on the absorbent bed which is responsible for all the filtration including elimination of heavy hydrocarbons.
• Heavy hydrocarbons can fill the filtration pores very fast thus rendering the coalescing filtration element useless.

Absolutely, you can install coalescing filters in pairs and in fact most of them are often installed in pairs.

You will install the coalescing filters in pairs to increase the filtration performance as well as reduce pressure loss.

The first coalescing filter will protect the second and most effective filter from heavy filtration.

It will do the heavy work of eliminating the heavy contaminants before they reach the second and most effective filter.

This will reduce the amount of work that the second filter does thus becoming more efficient in eliminating residual contaminants.

This will also reduce the build up of differential pressure and allow the system to function normally.

You must, however, think about changing the coalescing filter regularly maybe at intervals of between 3 to 6 months.

Coalescing filter element

Coalescing filters are meant for cleaning ultra-clean liquid and gaseous media in different applications.

You can also use it in the elimination of moisture condensations that form due to spraying due to gas stream obstacles.

It comes complete with a non-regenerated and replaceable cartridge thus increasing the level of efficiency.

Absolutely, there are alternatives where you can use the single filter alternatives.

You must, however, be very careful with the single filter alternatives as they may not be as effective.

One of the most successful alternatives to the double installation is the use of the 2 in 1 coalescing filters.

To reduce the pressure loss associated with the coalesced air filters, you can use the 2 in 1 filter alternative.

In many cases, the 2 in 1 coalescing filter work well in theory but usually fail to impress when it comes to reality.

When it comes to purchasing a coalescing filter, there are numerous factors that you need to take under consideration.

This include features such as the type of materials for making the bowl among other important features.

Here are the main features that you need to pay close attention to before purchasing a coalescing filter.

· Substance Exposure

You should consider a material that is compatible with the filtration media as well as filtration fluid.

In that case, having a metal casing bowl will work for the best coalescing filters.

· Pressure and Temperature

In this case, you should consider choosing a metal bowl instead of a polycarbonate material bowl.

This is because the metal bowl can withstand the high pressure and low temperatures of coalescing filtration.

· Manual or Automatic Drain

You can either choose to work with the manual or the automatic drainage of the coalescing filters.

Automatic drains will require a minimum of 0.35 bars to allow it to close adequately.

On the other hand, you have to check the manual drain on a regular basis to detect whether the bowl is full.

· Air Purity Class

You will have to consider the efficiency of the coalescing filters in terms of how much contaminants it can eliminate.

This will also go hand in hand with the quality of the coalescing filter you intend to purchase.

· Visual Service Indicator

You need to consider a coalescing filter that has an indicator that will alert you in case the filter bowl is full.

It will also indicate that the filter media is full or blocked and it is time to clean or replace it with a new one.

· Weight and Size

In this case, the size of the plant, as well as the type of material in use for making the coalescing filter, come in play.

Implying that you will determine the size of the coalescing filter in terms of the size of production plant.

Coalescing filters do not have the ability of performing most of the functions on its own.

You will, therefore, include other support equipment in the system to assist the coalescing filter.

Here are the main coalescing filter support equipment that you need to have.

· Fittings, Tubings and Brackets

You will need this type of equipment to assist you securing the coalescing filter elements and housing in place.

· General Purpose Filter

This type of filter will get rid of other types of contaminants from the fluid stream before reaching the coalescing filter.

Well, another factor that you need to pay close attention to is the coalescing filter housing.

Here are some of the factors that you need to consider when choosing a coalescing filter housing.

Coalescing filter housing

· Type of Material

You should consider using a type of material that can withstand the high pressure and temperature of the system.

In many cases, stainless steel work best since they can withstand the high pressure and volume of the filtration system.

· Weight and Size

In this case, you will choose a coalescing filter housing which can accommodate the size of the filter element.

It should also provide enough room for proper stabilization of the filtration process.

The weight will depend on the type of material that you choose to use on the filter housing.

Compressed air filter

Pneumatic coalescing filter is a device that you will use in the elimination of contaminants from compressed stream of air.

You can use the pneumatic coalescing filter to eliminate the contaminants from compressed air through different ways.

These mechanisms will trap the liquid or solid contaminants from the flowing air and then allow the dry compressed air through.

Under pressure, the contaminants will coalesce and form larger particles which will flow down to the collection bowl.

As soon as the collection bowl is full you can either automatically or manually drain the bowl.

China has numerous coalescing filter manufacturers that you can get in touch with for a good quote.

You should consider importing your coalescing filter from China because of the following reasons.

High-Quality Coalescing Filters

You will get the coalescing filters from China at very affordable cost and very high quality.

The type of coalescing filters from China uses high-quality materials in making the filters that meet value for your money.

Affordable Coalescing Filters

As much as the coalescing filters are of high quality, you will also get them at affordable prices.

Implying that you will spend considerable amount of money in purchasing your coalescing filter.

Proper Customer Care Services

China also has the best customer care services that will convince you to purchase from them.

Yu will get proper consultation services and information from the customer care service.

They are always ready and available to assist you with any type of information 24/7.

You will also enjoy the privilege of receiving designing assistance in case of a custom coalescing filter design.

Proper Transport System

Apart from the numerous road system that goes in and out of different cities, China has seaports and airports.

You can use the efficient transport system to transport the cargo from Chine either by sea or air.

After Sales Services

Manufacturers in China often try to maintain a proper relationship with you even after the sales.

They can offer additional services such as installation of the filter and training of your employees.

You may also get in touch with them for proper maintenance services if need be.

On average, you will spend around 40 to 100 dollars for the coalescing filter.

This will depend on the type, quality, and quantity of coalescing filters that you intend to purchase.

The higher the quality and the more coalescing filters you intend to purchase the more money you will pay.

Well, there are two types of filtration that you can choose from depending on the application.

Here is how the coalescing filter cartridge will compare to the standard filtration system.

Coalescing Filtration Cartridge

You will use the coalescing filtration cartridge in the process of eliminating liquid and particulate contaminants from compressed gas.

Apart from that, it depends on the principle of coalescing to get rid of the contaminants from the filtration media.

Implying that the contaminants will coalesce together to form larger particles thus drain off or fall by gravity.

Standard Filtration System

Standard filter system

On the other hand, standard filtration system is the elimination of particulate contaminants from different fluids.

In this case, you can use standard filtration in the elimination of different types of contaminants including solid particles.

Apart from that, you will also filter fluids that are moving at normal speed and not necessarily compressed.

There is also no coalescing of contaminants and you will get rid of them by cleaning the elements accordingly.

The main difference between the oil-water coalescing filter and air coalescing filter cartridge is the filtration media.

Oil-water coalescing filters use filtration media that is capable of elimination oil and water contaminants.

On the other hand, you can use air coalescing filter cartridge to eliminate particulate matter from a stream of flowing fluid.

The other difference is in the micro rating where the oil water coalescing filters have smaller micron ratings.

This will work efficiently in the process of eliminating the oil and water content from the flowing fluid.

Here the main factor that you will be looking at is the micron rating of the coalescing filter elements.

The higher the micron ration of the coalescing filter media, the more efficient the coalescing filter element.

You can also determine the efficacy of the coalescing filter element by performing a Multipass Test.

This test establishes the number of particles that go upstream through the filter that are larger than the micron rating.

You will divide the number you get by the number of particles downstream from the filter larger than the micro rating.

You can use the coalescing filter in a number of industries such as:

· Oil and Gas Industry

You will use the coalescing filters in the oil and gas industry to separate oil from the flowing gas.

It will trap the oil and allow pure gas to flow through for further processing.

· Petro-Chemical Industry

You will use the coalescing filter in the Petro-chemical industry to separate different types of liquids.

Apart from that, you will use it in the separation of liquids from gas fluids by trapping the liquids behind.

· Pharmaceutical Industry

In the pharmaceutical industry, you will use the coalescing filter to remove liquid contaminants from air.

This will lead to the formation of clean air that you can use to aid in proper respiration.

Coalescing filters consists of many different parts that assist in the proper functioning of the filter.

Here are the main parts of the coalescing filter.

Parts of coalescing filter

· Coalescing Filter Housing

This is the outer cover of the coalescing filter element that will protect it from the impact of the environmental factors.

· Automatic or Manual Fluid Drain

This is the part at the lower part of the coalescing filter where you will drain out the filter contaminants.

· Fluid Inlet and Outlet

You will introduce the fluid that you intend to filter through the coalescing filter inlet.

After filtration, you will be able to automatically eliminate the clean air from the filter through the outlet.

· Filtration Element

This is the part which has the filtration media that will trap the contaminants from proceeding with the fluid.

It is the main part of the coalescing filter that performs the main function of the coalescing filter.

· Collection Bowl

You will also collect the filtration residues that drain from the filtration element at the collection bowl.

It is important that you have all the knowledge about how a coalescing filter works.

Here is a step by step guide through the whole process of how a coalescing filter works.

Incoming Air

You will allow the compressed air to flow through the inlet of the coalescing filters.

Before that, you should make sure that the machine is in proper working condition and without contaminants.

You will also make sure that the collection bowl at the bottom is empty and ready to collect contaminants.

As the air flows into the coalescing filter housing, it will meet with the coalescing filter elements.

Actual Filtration Process

This is the point where the coalescing filter elements will get rid of the contaminants from the compressed air.

The contaminants that the coalescing filter eliminates will depend on the micron rating of the coalescing filter elements.

As the fluid flows through the filter elements, it allows the dry gas to pass through the filter elements.

The filter media will trap the oil and water contaminants and retain them within the filter media.

Coalescing of Particles

As more compressed air flows through the coalescing filters, it will trap more contaminants by the filter media.

As the contaminants increase, they coalesce together and form larger droplets of either oil or water.

The particles will become large enough to condense and fall via gravitational pull.

They will eventually collect down on the drainage bowl which you can automatically or manually drain as it fills up.

Air Outlet

The clean air will then leave the coalescing filter through the outlet of the coalescing filter element.

Well, in this case, you will be separating oil from a mixture of oil and air.

As the air flows through the system, it will pass through the filter elements with very fine micron ratings.

It will trap the oil from the oil-gas mixture and then allow the dry gas to move out through the outlet.

You will then collect the oil from the collection bowl at the bottom of the coalescing filter housing.

Coalescing oil filter

You can choose a coalescing filter element by looking at the following factors.

Micron Rating of the Coalescing Filter Element

This is the pore size of the coalescing filter element that you intend to choose.

You will settle on the micron rating according to the type of liquid you would like to filter.

Filtration Media

The coalescing filtration media vary according to the type of fluid you would like to separate from the compressed air.

This will also affect the micron rating of the coalescing filter element to a certain extent.

There are different types of coalescing filters that you can use in the process of filtration.

Here is a comparison between the electrostatic coalesces and the mechanical coalesces.

Electrostatic Coalesces

Electrostatic coalesces uses electric charges such as AC and DC or a combination of both to introduce coalescing of liquid molecules.

You can use them in water hydrocarbon emulsions in the offshore production platforms.

Electrostatic charges usually destabilize the emulsion thereby increasing molecule sizes which eventually fall to the bottom of tank.

Mechanical Coalesces

This type of coalesce will use different series of coalescing filters or baffle walls to separate hydrocarbon or water condensates.

It will separate them from emulsions and eventually coalesce them into larger molecules.

You can use it in the separation of water from natural gas or liquid hydrocarbons.

Simplex coalescing filter

Duplex coalescing filter

Simplex coalescing filters have a single unit of operation in comparison to the duplex with double operation units.

This makes the duplex coalescing filters to be more effective than the simplex coalescing filters.

This is because it uses more than one filter in the elimination of the contaminants from compressed air.

You can ensure optimal coalescing design by ensuring the following factors are taken into proper consideration.

Here are the main factors to consider:

• Separation efficiency of the coalescing filters
• Differential pressure of the coalescing filters
• Gas or Contaminants Content in the Compressed Fluid
• Quantity of liquid and solid particles to expect in compressed fluids

The main difference between the coalescing filter and the filter dehydrator is the mode of operation.

Coalescing filters usually use the condensation method to get rid of or collect the water or oil contaminants.

The particles will coalesce and form particles that are large enough to condense and collect at the bowl.

On the other hand, filter dehydrators use the principle of dehydration where the liquid contaminants are dehydrated.

It involves the elimination of the compressed air contaminants by heating and eliminating the liquid contaminants.

As you can see, there are a number of factors you should consider when choosing coalescing filter elements.

By considering these factors, you will definitely get highly efficient and reliable coalescing filters.

At FilSon Filters, we manufacture high quality and reliable filters.

For OEM or custom coalescing filters, contact us now.