Backwash Filters: The Ultimate FAQ Guide

If you’re looking for a filter that “clean and renew” itself, then backwash filter is what you need.

Today’s guide will answer all questions you may be having about backwash filters.

So, read this guide to be an expert in these filtration systems.

What is Backwash Filter?

This is a type of filter that consists of mechanisms of cleaning itself once clogging occurs on the filter.

It uses the filtration fluid to clean itself in a process that removes all the contaminants from the filter.

These contaminants low out of the system via the discharge valve. You can then continue with the filtration process.


Backwash filter system

How do Backwashing Filters Work?

The working of a backwashing filter is relatively simple as long as you understand the functionality of its various components.

The control valve is the one responsible for initiating the backwashing process of your filter.

The backwashing filter involves the reverse flow of the fluid that is flowing from the exit point to the entry point.

The flow of the fluid raises the floor bed of your filter due to its pressure, thereby cleaning it.

The floor bed usually contains a filter medium, which is generally a granular substance.

You can have a different filter medium depending on the type of your backwash filter.

The common filter medium available includes carbon, sand, zeolite, garnet, granular manganese dioxide, anthracite, and greensand.

Under regular operation, the filter bed is responsible for holding and trapping al contaminants as the fluid flows.

The flow of the fluid is generally from top to bottom or from outside to the inside.

As this happens, there is the creation of channels on the bed of the filter. This is because fluid tends the following path with less resistance.

Channeling has the effect of reducing the effective filtration process of your fluid.

Once the backwashing process is complete, the fluid flows through the control valve into the drainpipe of the filter.

This process takes a couple of minutes before the normal filtration process continues.

The control valve is responsible for initiating this process.

Are Backwashing Filters the same as Self-cleaning Filters?

Yes. Backwashing filters are the same as self-cleaning filters.

They are a type of self-cleaning filters since they can clean themselves during the filtration process.

They do this by using the same fluid that they are filtering.


Self cleaning filter

What are the Benefits of Backwash Filters?

Backwash filters offer several benefits both to your fluid as well as the operation of your equipment.

Such benefits include:

  • Minimizes on Costs

The use of backwash filters helps in reducing the cost of having to replace worn out and inefficient filters.

This is through cleaning the available filters ready for the filtration process.

  • Efficient filtration

The filtration process removes all the contaminants present in a fluid.

Filters hold these contaminants during the filtration process resulting in their clogging, which hinders efficient filtration.

However, the backwash filter clears the clogging process offering an efficient filtration process for your application.

  • Equipment durability

Clogging affects the quality of your filtration process.

The inadequate filtered fluid causes your equipment or machinery not to function appropriately.

However, backwash clears the clogging, which ensures you have clean fluid for the proper functioning of your machinery.

  • Saves time

Backwash filters tend to take less time filtering your fluid as compared to conventional filters.

This is because of the backwashing mechanism, which ensures cleaning of the filters when there is clogging.

Less time filtering your fluid implies high production for your equipment.

Are Backwashing Filter Systems Automated?

It depends on the kind of backwashing filter that you select.

There are two types of backwashing filters available for your selection, that is, automatic and manual backwashing filter system.

The manual backwashing filter system involves manual controlling of the backwashing process.

Under this type, you have to check the contamination level of the backwash filter physically.

In an Automatic backwashing filter system, all the operations are computer-controlled. This saves time and is efficient.

Once clogging occurs on the backwash filter, the system automatically shuts the filtration process and immediately initiates the backwashing process.

What are the Disadvantages of the Backwash Filter System?

Like any other type of filtration system, you will experience several limitations when using a backwash filter system.

Such limitations include:


Backwashing filter

  • Cost

The cost of purchasing a backwash filter is relatively expensive when you compare it to the other types of filters.

You, therefore, have to budget for both the purchasing and maintenance of the backwash filter system.

  • regular maintenance

To enhance its performance, you have to maintain your backwash filter regularly. This can be time consuming and tiresome.

Why is Backwashing Important?

Backwashing plays a critical role in the proper filtering of your fluid.

First, backwashing ensures you have clean filters for your operation.

This offers you quality filtration of your fluid.

Through proper filtration, you have durable filters, as well as your equipment.

Once there is proper filtration due to a quality filter, there is the efficient operation of your application.

How Long Do Backwashing Filters take?

The duration of backwashing filters depends on several factors.

First, the pressure of the fluid, which affects the cleaning procedure.

The size of the backwash filter will determine how long it takes.

In general, the larger the backwash filter, the more time it takes.

The size and type of contaminants also determine the time it takes for cleaning your backwash filters.

Denser and oily contaminants take more time during the backwashing process.

At what PSI Should you Backwash Filter System?

The standard PSI of a backwash filter system should be more than the operating pressure of your backwash filter.

This will efficiently remove all the contaminants from the backwash filter.

Where can you use Backwash Filters?

The use of a backwash filter is vital in various applications.

There common application areas for backwash filters are:

  • Pharmaceutical industry
  • Food industry
  • Locomotive industry
  • Manufacturing industry

What is the difference between Manual and Automatic Backwash Filter?

The main difference is in its operation.

The manual backwash filter utilizes a manual set-up for cleaning itself during the backwashing process.

An automatic backwash is a computer-controlled type of backwash filter.

In this type, you set the operations in a computer, and the backwash filter picks the commands and executes them.

What is the Function of the Backwash Filter?

A backwashing filter plays a critical role in the filtration of your fluid through holding contaminants as it flows.

Its ability to clean itself during the filtration process helps in reducing the operational cost.

How does Inside-outside and Outside-inside Flow compare?


outside in vs. inside out filtration

The main difference between these two is in the flow direction.

In an outside-inside flow, the fluid flows into the backwash filter.

In an inside-outside flow, the fluid flows from the backwash filter to the outside.

Inside-outside flow is common during the backwashing process.

The outside-inside flow is vital during the filtration process of the fluid.

The pressure of the inside-outside flow is relatively lower than that of the outside-inside flow.

This is because the entry point of the inside-outside flow is smaller.

An outside-inside flow has a large diameter of the entry point and a smaller diameter of the exit point.

What affects Backwashing Rates in Filter Systems?

Optimum backwashing rate is ideal in offering quality filtration for your fluid.

A low backwashing rate causes poor filtration of your fluid.

A high backwashing rate can lead to the busting of the filtration medium.

Among the factors that affect the rate of backwashing in your filter system includes:

· Operating Temperature and Pressure of your Fluid

If you have a high operating temperature, the backwashing rate will reduce.

This is because of the effect it has on the backwash filter system.

Low operating temperature also affects the backwash rate since the fluid flow will reduce.

Low pressure reduces the flow of the liquid, which affects the backwashing rate.

 You must ensure that both the temperature and pressure are at an optimum rate for effectively handling the backwash rate.

· The Size of your Backwash Filter

A large backwash filter ha a lower backwashing rate when you compare to a small backwash filter.

The capacity of the backwash filter affects the backwashing rate if all the other factors are constant.

· The Type of Filtration Media

There are different types of filtration media, which affects the backwashing rate.

Pleated backwash filter has a low filtration rate due to the number of pleats available.

A carbon backwash filter or gravel backwash filter has a high filtration rate due to their size and nature.

· Type of Fluid and Contaminants

A fluid with a low viscosity has a high backwash rate when you compare with one that has a high viscosity.

This is due to the fluid flow, which is faster under pressure than the one with a high viscosity.

If the sizes of your contaminants are dense and have irregular, they will reduce the backwashing rate.

This is because one has o apply for more pressure to remove the contaminants

When should you replace Backwash Filters?

For continuous and quality filtration processes, there is a need for frequent filter replacement of your backwash filters.

Among the factors that should make you change your backwash filters include:

  • Tattered filter element

If your backwash filter has a tattered filter element, then you need to replace it.

The tattered filter element results in poor filtration of your fluid.

This is because contaminants can flow through the filter into your equipment.

  • Poor filtered fluid

When your activated charcoal cannot hold any more contaminants, you have to replace it.

This is due to the saturation of the charcoal by the chemicals present in your fluid.

 You will notice a color change on the activated charcoal and a gain in weight hen it has reached the saturation point.

  • Crushed cartridge

if the inner part of your cartridge is plastic, the chances are that it may collapse due to weight over it.

If it happens, the entire cartridge collapses, which affects the filtration process.

When such occurs, then you need to replace your backwash filter

  • High-pressure readings

If you notice pressure readings that are above the normal recordings, then you have to replace your backwash filter.

The main cause of this has a dirty cartridge.

If you try cleaning the cartridge, but there is no change, then you have to replace it with a new one.

  • Old backwash filter

If your backwash filter works for a given time without replacement, then you need to replace it.

This way, you have a guarantee of the quality of your filtration process.

How does Backwash Filters compare to Normal Filters?


Filter and backwash filter mode

A backwashing filter has a mechanism of cleaning itself when clogging happens.

A typical filter depends on the manual cleaning of the filter element during clogging.

Using a backwash filter results in high production since there is little disturbance during the filtration process compared to regular filters.

The core function of both backwash and ordinary filters is to remove contaminants from fluids.

A backwashing filter has a wide range of application when you compare to a normal filter.

Which Filtering Media is in Backwash Filter?

A filtering media is that part of your backwash filter that holds contaminants from flowing through your application during operation.

Different filtering media are depending on the type of backwash filter.

The primary filtering media are:

  • Carbon

Carbon, in this case, activated charcoal is the most preferred option for backwash filters.

This is because they are relatively cheaper and have a wide range of uses.

Activated charcoal is effective in removing chemicals from different fluids.

However, it requires frequent replacement, which in the long run, is quite costly.

  • Cartridge

There are different cartridge materials available for use on your backwash filter.

These include plastics, pleats, sheets of metals, and carbon papers.

What are the Types of Backwash Filters?

There are two main types of backwash filters, that is, automatic and manual backwash filters.

An automatic backwashing filter is a pre-programmed filter that cleans itself after a selected schedule.

It is an efficient and faster way of filtering your fluid. However, it is costly, which means you have to budget appropriately both for purchasing and maintenance.

A manual backwash filter is one that requires manual scheduling of the backwashing process.

The advantage of this is that it is relatively cheaper than an automatic backwash filter.

However, it is slow and requires frequent maintenance, which affects the filtration process.

Other types of backwashing filters depend on the filter media available in them. These types include;

· Carbon Backwash Filter

The primary filtering media in this type is carbon.

Carbon is the preferred option due to its physical characteristics. Such include;

A carbon backwash filter is an ideal option for filtering water, air, and industrial gas.

Among the contaminants it removes includes siloxanes and chlorine and hydrogen.

It is relatively cheaper and highly effective. 

However, it has a low service life, which requires constant replacements.

This is quite costly.

· Cartridge Backwash Filters

This type uses cartridge as the main filter medium.

They are ideal in the removal of contaminants such as solid particles and even chemicals from fluids.

You can have different materials for the cartridge backwash filter.

They include wound strands of materials like polypropylene.

They are relatively expensive when you compare to carbon backwash filters.

How does Carbon Backwash Filter compare to Cartridge Backwash Filters?

The carbon backwash filter uses activated charcoal for filtration.

Cartridge backwash filters consist of different wounded materials such as polypropylene.


Activated carbon filter

Cartridge backwash filters are relatively expensive when you compare to carbon backwash filters.

Carbon backwash filters are ideal for filtering contaminants that are chemicals such as siloxanes, chlorine, and hydrogen.

Cartridge backwash filters effectively filter contaminants such as solid particles and certain chemicals.

Carbone backwash filters are durable when you compare to carbon backwash filters.

Carbon backwash filters require constant replacement for it to function appropriately.

This is costly in the long run.


Cartridge filter

What should you consider when Purchasing Backwash Filters?

With the availability of different backwash filters in the market, it becomes a challenge selecting an appropriate one for your application.

However, paying consideration to critical factors will help you in deciding the right one for your application.

They include:

  • Purpose

Different backwash filters serve different filtration functions. This brings out different filtration quality standards.

Also, the availability of different filtering fluids affects the type of backwash filter that you select.

When selecting a backwash filter for your application, you have to check on the purpose you want it to serve.

  • Filtration fluid

different filtration fluids have different characteristics that affect the filtration function.

Such features include the fluid viscosity, operating temperature, and pressure.

The backwash filter you select should not react with fluid and should ensure there is proper filtration process.

  • Filtration media

There are different filtration media for use, depending on which fluid and the type of filtration you want.

The typical filtration media are carbon, sand, zeolite, garnet, granular manganese dioxide, anthracite, and greensand.

Each of these media has its unique ability to hold contaminants of different sizes.

  • Filter mesh size

The backwash filter mesh size is the size of the individual pores of the filter.

These sizes affect the quality of filtration since it holds particles that are higher than the given size.

Depending on the quality of filtration, you may have to select a backwash filter with the correct filter mesh size.

  • Backwashing rate

The backwashing rate has the effect of determining the duration of filtration and the speed of operating your application.

A higher backwashing rate implies that it takes less time for the backwashing process to take place and the overall filtration process.

This means your equipment operates at a higher speed.

  • Type of backwash filter

There are generally two types of backwashing filters, automatic and manual.

The choice depends on how you want your equipment to run and the available resources.

How do you Disinfect Backwash Filters?

Disinfecting backwash filters is vital for the overall quality of the filtration fluid.

This is critical, especially in human sensitive products such as milk and juice.

You must use a disinfectant that is non-reactive to the filter and also to the fluid that you are filtering.

After disinfecting your backwash filter, you should let your backwash filter to dry under high temperature before using it.

You can achieve this through the use of the sun or machines to sterilize it.

Are there Customized Backwash Filters?

Yes. You can quickly get a customized backwash filter.

However, you need to submit the specification of the backwash filter to your manufacturer in advance.

A reliable manufacturer will streamline these specifications to ensure they meet the necessary standards before manufacturing.

Which Parameters Affect the Performance of Backwash Filters

An effective backwash filter should offer the necessary performance as per the expectation of the user.

The common parameters that you can check on the quality of your backwash filter include:

  • Size of the contaminants

Choosing the correct size of basket filter that corresponds with the contaminant sizes facilitates its performance.

The backwash filter holds all the contaminants of that particular size, thereby facilitating the filtration process.

  • Type of fluid

Different fluids have different characteristics, such as viscosity and reaction to the backwash filter.

An adverse reaction implies that over time, there is a compromise on the performance of the backwash filter.

Low viscosity tends to slow down the filtration process hence lowering the performance of the backwash filter.

  • Operating temperature and pressure

A high fluid operating temperature causes wear and tear to the backwash filter, especially if it does not have the corresponding temperature limits.

For the adequate performance of your backwash filter, it has to have a higher operating temperature as compared to that of the operating fluid.

The operating pressure results in the bursting of the backwash filter, especially if it does not have high strength.

This compromises the performance of your filter.

It is, therefore, vital for the backwash filter to have a high operating temperature and pressure than that of the filtering fluid.

  • Filter mesh size

The filter mesh size should be less than the size of contaminants that you want to filter from the fluid.

A higher filter mesh size than that of the contaminants implies contaminants will flow through the filter into your application.

This results in the low performance of your backwash filter. What are the Quality Standards for Backwash Filter?


3 modes of filtration

Proper backwash filter manufacturing should adhere to given standards before they are out in the market.

The main quality standards that a given backwash filter should certify are:

  • Burst resistance standards
  • End load standards
  • Flow fatigue characteristics.
  • Bubble point standards
  • Fluid compatibility standards
  • Flow characteristic standards
  • Filtration performance standards

Clearly, backwash filters play an integral role in modern filtration systems.

However, analyzing and evaluating every aspect covered in this guide is quite critical.

At times, the information available out there can be so overwhelming. That’s why FilSon team is here to help – contact us now.

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