Vacuum Pump Filter: The Ultimate FAQ Guide

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

It compiles are questions, with an aim of giving you insights and making you an expert in the vacuum pump filter industry.

So, if you want to learn more about vacuum filters, read this FAQ guide:

Table of contents hide

What is Vacuum Pump Filter?

Vacuum pump filters are devices designed to restrain particulate matter and dust from entering or leaving your vacuum pump and soiling the components of the vacuum system.

They play an essential role in any vacuum pump filtration system.

Vacuum pump inlet filter

By preventing the vacuum pump from sucking in dirt, vacuum pump filters are helpful in hindering avoidable wear.

The device offers minimal pressure losses and ensures energy efficiency and durability.

Furthermore, it makes sure your vacuum pump maintains functioning at optimum levels of performance.

How many Types of Vacuum Pump Filters are there?

There exist two primary types of vacuum pump filters; they include:

i. Inlet Filters

This type of vacuum pump filtration system is often installed at a position inline before the vacuum pump intake.

They are made to protect a variety of vacuum pumps from contamination as a result of particulates like:

  • Stray fibers
  • Bagging film fragments
  • Dust commonly found in industrial manufacturing setup

In inlet filters, the gas flow enters the exterior body of the filter system.

It then goes via the filter element from the exterior to interior.

Finally, it leaves the filter system to the vacuum pump.

There are various types of filter element suitable for different applications.

However, a pleated polyester or paper element seems to be the ideal inlet filter element for dusty uses.

The pleating provides a large surface area for the stream of gas to go through.

Vacuum pump paper air filters

ii. Exhaust Filters

Exhaust filters commonly find application on oil sealed rotary vane vacuum pumps.

The primary role of this type of vacuum pump filter is to minimize or eliminate oil mist that often form due to operation of the vacuum pump.

Vacuum pump exhaust filters help in maintaining vacuum pump exhaust clear of all noticeable oil mist, even if it is soaked with oil.

The vacuum pump may expel the exhaust gas into a clean area or it may be recirculated into the process.

This prevents the necessity to run exhaust pipes and ductwork outside.

Exhaust filters are fitted with highly efficient filter cartridge that constantly clears out the collected liquid.

It enables you to reclaim expensive lubricating oil and lead to longer service life of the vacuum system.

You can find these filters for vacuum pumps having flow spanning from 3-850 cfm.

There are two main types of vacuum pump exhaust filters:

· Traditional Exhaust Filter

It is commonly referred to as vacuum pump coalescing exhaust filter.

It will confine majority of the oil mist, retain the oil within the pump and expel into a clean work area.

Basically, coalescing implies that the oil flows back into the pump after condensing on the interior of the filter element.

Vacuum pump filter

· Capture Filter

 It is another type of exhaust filter.

It has the same working principle as the traditional exhaust filter, though it as well comes with an exhaust port.

In vacuum pump capture filter, you can fix a hose to the exhaust port.

The hose connection directs any oil mist that passes across the filter element to a hood, eliminating them from the vacuum pump system.

Which are the Main Components of Vacuum Pump Filter?

A vacuum pump filter assembly is made of the following key parts:

Vacuum filter elements

  1. Filter housing; which encloses the components and is made of either aluminum or stainless steel.
  2. Filter element; which captures the particulate matter in the case of inlet filters and oil mist for exhaust filters.
  3. Drain port; usually positioned at the bottom of the filter and helps in removing any collected oils.
  4. Filter Inlet; which is attached to the exhaust of the vacuum pump (exhaust filter) or allows in air into the vacuum pump (inlet filter)
  5. Filter outlet; which is connected to the vacuum pump inlet (intake filter) or exit for gas stream from vacuum pump (exhaust filter)
  6. Entrainment separator pad; in the case of multiple elements and helps to minimize chances of oil carryover

Which are the Types of Filter Elements for Vacuum Pump Filters?

Acid Neut – The filter element has potassium hydroxide which helps in neutralizing acidic vapor jets.

Neutralizing most of the acid jet ensures protection of the pump and subsequent equipment.

Activated Carbon – This type of filter element captures organic solvents such as aromatic and aliphatic solvents.

It can trap up to 20 percent by weight of solvents passing through.

Since the activated carbon consists of micro-crystalline graphite, it is a perfect choice for trapping hydrocarbon-based compounds such as oils. 

Moreover, you can use this filter element to trap mercury.

Activated Alumina – Elements of this type are ideal for acidic streams and hydrocarbon molecules of high molecular weight.

Copper Mesh – They offer a broad surface area for capturing some condensable mists.

The primary role of this filter element is to prevent large coarse particulates matter from entering the pump.

They as well assist in preventing oil backstreaming though the molecular sieve filters are the best for this kind of application.

Cellulose Acetate – An outstanding filter element that can function as both strong acid and particulate trap.

Made of cotton fibers and virgin wool, these vacuum pump filter elements adsorb the substances and retain them on its broad surface area.

They are an ideal option for trapping small particles since they are capable of reaching retention sizes within the low micron scale.

Molecular Sieve – employs 13x zeolites for filtering, with the pores in the zeolite that capture the molecules.

They are typically applied to prevent backstreaming of oil to the pump at low pressure.

Stainless Steel Mesh – Have similar use as copper mesh filter element.

304 stainless steel mesh is the best option for trapping particulates in systems that involve more basic or acidic vapor streams. 

They also aid in stopping oil backstreaming even though molecular sieves are more efficient.

How does Vacuum Pump Filter Assembly Look Like?

Here are some of the images showing how vacuum exhaust filters and inlet filters look like.

Vacuum pump exhaust filter

Figure 6 Vacuum pump inlet filter

How do you Clean Vacuum Pump Filter?

Before you start the cleaning process, you need to observe all the needed precautions in case hazardous or toxic compounds have been pumped.

You should put on protective clothing when handling contaminated filter elements and filters.

Make sure that the O-ring of the filter element is in position when you fix new filter elements.

When you do not ensure this, there will be no treatment of the exhaust gases of the vacuum pump.

The oil mist will be expelled into the work environment and might result in injury to workers.

Follow these steps when cleaning vacuum pump filtration system:

  1. Turn off the power supply to the vacuum pump.

2. Polish clean the exterior surface of the vacuum pump filter.

3. Detach the drain plug to clear out the lubricant from the filter. Return the drain plug after completely draining the filter.

4. In case you have an exhaust hose connected to the outlet of the filter, disconnect it.

5. Unfasten and pull out the screws which join the top body to the bottom body, then detach the top body.

6. Pull out the filter elements and change them if necessary. Discard the worn out elements safely.

7. Polish clean the interior of the top body and bottom body together with the mating surfaces. Ensure not to remove the D-seal.

8. Make sure that the O-ring of the mist filter element is in position in the bottom body, then fix the new elements; make sure that the foam sealing rings placed at the top and bottom of the filter elements are rightly seated.

9. Refit the top body to the bottom body and tighten using screws taken out in Step 5.

10. After fitting, reconnect the exhaust hose to the filter outlet.

What should you consider when choosing Vacuum Pump Outlet Filter?

There are several factors to consider when selecting a vacuum pump exhaust filter.

Let’s look at the main issues to consider to make sure you choose the right vacuum pump outlet filter for your applications.

Two stage vacuum pump filter

· Low Maintenance

A filter system that needs frequent replacement of paper filter needs to be avoided since the paper will get filthy very fast.

Moreover, you should not buy a vacuum pump filter that needs a lot of regular maintenance.

Though a filter system that needs minimal maintenance may be costly, the hassle and time saved throughout its life is worth the cost.

· Capacity

It is essential to establish beforehand the oil mist volume that you will be required to filter to maintain a safe environment.

For example, not all vacuum pump exhaust filters permit the same quantity of gas to pass through during the process of filtering.

Yet, you should not exceed the limits of your vacuum pump filter.

Therefore, to choose the right filter system for your applications, you need to go for one that permits for at minimum three times the working capacity required.

· Extra Features

Apart from choosing a vacuum pump filter that removes oil mist, you need to look for one that equally eliminates other hazardous contaminants and chemicals.

What are the consideration in designing Inlet Vacuum Pump Filter System?

You should consider the following factors when designing a vacuum pump inlet filter system:

i. Particulate Retention

Basically, particulate retention is how effective a filter element is at capturing particulate matter.

Each type of filter element has distinct efficiency rating that represent how well it performs at trapping a variety of particulates.

Therefore, particulate retention is a key consideration when designing a vacuum pump inlet filter system.

This is because with time there will be accumulation of particulates in the vacuum pump.

This build up may result in severe problems leading to high maintenance cost or downtime in production.

ii. Pressure Drop

Pressure drop is essentially the vacuum difference between the inlet and outlet of the vacuum pump inlet filter.

Pressure drop across the filter is critical in that if it is in excess, the cost of running the vacuum pump goes up.

High pressure differential leads to a higher requirement in capacity.

That is, the vacuum pump needs to produce a deeper vacuum to compensate for the loss through the intake filter.

When you have a fixed vacuum capacity, there will be a vacuum loss at the production equipment.

· Serviceability

You should make sure that whatever design of inlet filter you choose must have elements that offer ease of cleaning or changing.

Majority of vacuum pump systems come with single inlet filter arrangements, which compels you to shut down the system when changing or cleaning the filter elements.

A better configuration is to fix dual inlet filter system that makes it possible for one side to continue operating as the other is being cleaned.

This facilitates maintenance of low pressure differential during the entire cycle of production.

Furthermore, it enables demand applications to achieve maximal vacuum at the place of use.

What is the Effects of Wet Filter when using Vacuum Pump?

The wetness would gradually weaken the filter till the filter element raptures and lets the trapped particulate matter into the vacuum pump.

In addition, wet filter also as the possibility of producing mold.

What is HEPA Filter?

HEPA is an acronym high-efficiency particulate air.

HEPA filter is a kind of mechanical air filter systems that function by forcing air across a fine mesh that captures unwanted particulates.

They find use in various applications from medical facilities and homes to aircrafts and automobiles.

A true vacuum pump HEPA filter can trap as much as 99.97 percent of particles as tiny as 0.3 microns.

For this reason, when you connect a HEPA air filter to a vacuum pump, it prohibits particulate contaminants from getting into the system.

What are the uses of Vacuum Pump Filter?

Vacuum pump filters, particularly inlet filters are made to inhibit particulate matter and dirt from getting into or exiting the vacuum pump and fouling the parts of the vacuum systems.

In addition, exhaust filters prevent oil mist generated during functioning of the vacuum pump from being expelled into the environment.

How do you select Vacuum Pump Filter Housing?

Vacuum pump filter element and housing

Most of vacuum pump filter housings are made of two materials, that is, stainless steel and aluminum.

The choice between the two materials will depend on the exhaust chemical composition.

When application involves corrosive chemicals or temperatures beyond 120°C, you should opt for stainless steel.

The size of the housing will be based on the vacuum pump’s maximal free air displacement.

You should not opt for a housing having a flow rating lower than the pump as this will reduce efficiency.

What are the Advantages of Vacuum Pump Filters?

  • Performs faster filtration than other filtration systems, usually requiring less than a minute with right vacuum source and good seals.
  • Can effectively manage viscous fluids beyond 40 Cst.
  • Typically the filter utilizes only a single pump to create vacuum and deliver pressure. Thus uses much reduced power compared to other types of filtration systems.
  • Employs pump suction vacuum together with gravity for filtration. Pressure differential applied is roughly 4 meters of fluid column thus accumulates more layer of dust to function way better compared to other types of filters.
  • long service life
  • Compact structure, and
  • Easy operation

What should you consider in Sizing Vacuum Pump Filter?

There are a number of factors to consider when sizing a vacuum pump filter.

Let’s look at some of the main considerations when sizing vacuum pump filters.

Vacuum pump filter element

· Type of Vacuum Pump

The major types of pump include rotary screw, reciprocating, liquid ring, rotary vane and rotary piston vacuum pumps.

Every pump type generates its distinct oil discharge features and needs the right filter media size to effectively trap and remove oil aerosols.

· Particle Characteristics 

Knowing the size and type of particles sieved enables you to choose the correct micron size for the vacuum pump filter.

For instance, surface or pond water has large organic matter, like leaves and algae, whereas well water has inorganic debris, like sand.

Generally, inorganic matter will need a smaller-sized filter element to capture the sand and residue that would pass across larger-sized types.

Water is just an example, you can as well filter viscous fluids, like paint, paper coatings and honey among others. 

· Maximum Operating Flow

Flow rate is also an important factor to consider when sizing your vacuum pump filter.

For instance, a 2″ filter that permits a flow of 100 gpm will not be suitable for a vacuum system working at 150 gpm.

You should choose a filter size having an operating flow greater than that of your application.

· Minimum and Maximum Pressure of Operation

Each filter has a maximum operating pressure rating.

Therefore, it is crucial to ensure a precise measurement of maximal pressure when you are sizing and choosing a vacuum pump filter.

Though minimum pressure of operation is not a necessity for all filter types, it is essential when utilizing automatic, self-cleaning filter system.

You must maintain minimum operating pressure when you engage the flushing mechanism of the filter.

· Pressure Drop

There are various factors that influence pressure drop, like viscosity, flow rate, contaminants present, and filter media.

Since the size of filter element contributes to pressure drop, it is also an essential consideration when sizing your vacuum pump filter.

Pressure differential increases as the filtered residues reduce the surface area of the filter.

The desired fluid flow across the filter will be affected once it reaches a point where the pressure to surpass the pressure drop is too great.

The loading of the particulate matter and the surface area of the filter will dictate the frequency required to empty the filter element.

A small-sized filter will result in very high pressure drop, this will lead to frequent production downtime and may reduce the life span of the vacuum system.

· Air Velocity

Air velocity as well determines how you size your filter media. Maintaining the correct air-to-media ratio is important for efficient filtration process.

What is Vacuum Pump Coalescing Exhaust Filter?

A coalescing exhaust filter is a device used for separating oil mist into its respective components via several processes.

They are designed for application in inlet and exhaust of vacuum pump systems.

The device can have an efficiency of up to 99.999 percent and function in pressures greater than 5,000 PSI.

This type of exhaust filter work by separating aerosols and liquid droplets from a gas.

In a coalescing filter mounted within a housing, the moist gas is passed across the filter element from the interior to the exterior.

The inside capture layer is made up of highly effective coalescing material whereas the outside part is of a rougher drainage layer.

Vacuum pump coalescing exhaust filters can be classified into two types; the mechanical coalescing filters and electrostatic coalescing filters.

The mechanical type uses filters or baffles while the electrostatic coalescing filter utilizes AC fields or AC or a blend of both to force oil mist to coalesce.

How does Vacuum Pump Exhaust Filter compare to Oil Mist Eliminator?

Often, people prefer to use oil mist eliminator instead of vacuum pump exhaust filter.

However, the two terms can be used interchangeable to refer to the same device.

Oil mist eliminators are modelled to capture oil mist or vapor which leaves the vacuum pump when you start it.

During prolonged functioning or when you utilize the gas ballast valve to outgas or purge oil of the vacuum pump.

During the initial launch or when you open the gas ballast valve of the vacuum pump, you will easily observe the oil mist as a fine mist that gets released into the work environment.

The oil mist comprises not only of hydrocarbons but also has numerous other semi-volatile and volatile organic compounds that were contained in the lubricant.

The oil mist eliminator is devised to capture this plume of oil vapor and drain it back to the pump.

How does Oil Mist Filter Operate?

Oil mist eliminators, usually installed on the exhaust port of vacuum pumps.

They comprise of a replaceable filter element contained inside an aluminum, stainless steel or plastic housing having an oil collection compartment.

As the fume exhaust from the vacuum pump gets out via the middle of the oil mist filter, it must go through the oil mist filter element.

The large surface area of the filter media adsorbs the oil mist and collects the condensed oil in a reservoir found at the bottom of the oil mist eliminator.

The recovered oil is then directed back to the vacuum pump.

After going through the oil mist eliminator filter element, the vacuum pump’s exhaust gets expelled out through the exhaust port of the filter.

Most oil mist filters come with one element, though those fitted with two filter elements are fairly more effective at capturing analytes.

Oil mist filter

Why should you Filter Exhaust from Vacuum Pump?

The main benefits of installing vacuum pump exhaust filter comprise of:

1. Emit Clean Air into the Environment

A vacuum pump will release visible oil mist and smoke into the air.

But fitting an oil mist eliminator will remove 99.9 percent of the smoke and oil mist from the exhaust fumes of the vacuum pump.

This will inhibit buildup of oil in the ambient air that could as in turn lead to health hazards.

Obviously, it will violate your country’s environment and occupational safety and health regulations.

2. Remove Oil in Pipes and Ductwork

When a vacuum pump emits oily air, the contaminants get circulated throughout the vacuum system via the ductwork and connecting pipes.

This can result in dirty inlet air for other devices such as packaging machines, compressors, etc.

3. Recover Costly Lubricating Oils

Installing a vacuum pump exhaust filter can enable you recover high-cost lubricating oils and recirculate the filtered oil to the pump.

Doing this reduces the general costs of maintenance.

Are there Disadvantages of using Vacuum Pump Filter?

Absolutely, there are negligible disadvantages of vacuum pump filter considering their overall benefits to your vacuum system.

  • Requires high initial capital and operating cost. The filter media (high-collapse kind) and housings should be designed to sustain peak system pressure.
  • The suction force may force fine particles past the pores of the filter element, and probably lead to contamination of the successive equipment and work environment air.
  • Difficult to clean particularly as needed for food grade uses.

What are Quality Standards for Vacuum Pump Filters?

Here are some of the quality standards that vacuum pump filters should comply with.

· cGMP Standards

Vacuum pump filters used in pharmaceutical, medical and food and beverage industries need to comply with current Good Manufacturing practices Standards.

· ISO 8573 Compressed Air Quality standards

This standard requires that your vacuum pump filter ensures that the air it releases is safe for human health.

Publication 7 of the SQF Code stipulates that compressed air utilized in food production should be clean and pose no hazard to food safety.

Moreover, it should be constantly monitored for purity.

· Pressure equipment Directive 2014/68/EU

The PED 2014/68/EU deal with the design, production and conformity evaluation of stationary pressure devices with a maximum permissible pressure higher than 0.5 bar.

· IECEx Certification

Your vacuum pump filter of choice should have IECEx certification; a global system for authentication of equipment for application in explosive environment.

Which Industries use Vacuum Pump Filter?

Different industries use different vacuum pumps and vacuum pump filtration systems.

Here are some of the industries that use vacuum pump filters in their day-to-day applications:

  • Electric Power
  • Chemical industry
  • Pulp & Paper industry
  • Mining, pharmaceutical
  • Plastic industry,
  • Medical industry,
  • Environmental industry,
  • Food & Beverage
  • Packaging industry
  • Metallurgical industry and
  • Sugar industry

What is Multi-stage Filtration System?

These are filter systems that have layered filters or two or more stages to gradually eliminate particulate matter and oil mist.

The first filtration stage could be made up an oil mist eliminator.

While the second filter may comprise of a replaceable charcoal trap to eliminate volatile organic substances from the vacuum system.

Multi-stage filtration systems help in filtering out particulates and corrosive fumes that can foul the vacuum pump system.

This in turn extends the maintenance cycles and minimizes downtime.

These systems guarantee an almost total filtration of the through-flow, with a variety of filter elements available for various fields of application.

How efficient is Vacuum Pump Filter System?

Vacuum pump filter element design enables it to have an efficiency of up to 99.999% on .2 micron diameter particulates.

Most of them are rated at 5ppm at 60 Tor maximal carryover.

When should you Replace Vacuum Pump Filter?

The only service commonly needed of vacuum pump filter is the periodic substitution of the filter element.

You should carry out this replacement once annually under normal conditions, unless you are purging corrosive or acid materials into the vacuum pump.

Vacuum filter element

Since the filter element is commonly manufactured from paper composite, the acid or corrosive chemicals can make it to speedily disintegrate.

In this case, you will be required to replace the filters more often.

Replacing the filter is a very straightforward process, you simply unbolt the two chambers of the vacuum pump filter housing and substitute the filter element using a new one.

What is the Purpose of Vacuum Filtration?

Vacuum filtration is the standard method employed in the separation of solid-liquid mixture when the objective is to keep the solid.

Also known as suction filtration, this technique is relatively quicker than gravity filtration, usually requiring less than a minute.

Vacuum filtration is more effective in eliminating liquid residues, resulting in a purer solid.

This is particularly crucial in crystallization, since the liquid may have soluble contaminants that have the potential of adsorbing back onto the surface of the solid after evaporation of the solvent.

Clearly, vacuum pump filter plays an integral role in most industrial setups.

It not only ensures efficiency, but guarantees the reliability of the entire process.

With the information in this guide, I hope you can choose a suitable vacuum pump filter for your specific applications.

But, in case you have any questions about the vacuum pump filter, FilSon team is here to help.

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