How Do I Select and Properly Size an Inlet Filter?

Last Updated On: 6/19/2023

By: Clint Browning

inlet filters for blower, compressor, vacuum pump


Selecting an Inlet Filter for Your Blower, Compressor, or Vacuum Pump.


The key to achieving peak output performance from your compressor, blower, vacuum pump, engine, or any other machine that moves, processes, or consumes air – is ensuring clean, unrestricted air flow at the inlet. Appropriate filtration technology is essential to optimizing and protecting your equipment and working environment, even when severe external conditions are present. A critical factor for optimizing performance from your equipment is properly selecting and sizing your filter cartridge and housing. Through selecting the correctly sized filter, your equipment will operate smoothly over a longer period of time while also avoiding costly maintenance or downtime.  Although it is always best to enlist filtration experts in the selection process, this article provides general guidelines for selecting and sizing particulate filters to protect your equipment.

Inlet filters come in many configurations and sizes.  The two main types of inlet filters include:

  • Inlet Vacuum Filters, or Inline Vacuum Filters for vacuum pumps
  • Inlet Air Filters, or Ambient Air Intake Filters for Blowers, Compressors, Fans, Engines

Selecting the appropriate filter depends on the type of equipment being protected and the conditions in which the filter will be deployed.  Gathering as much application information as possible up front, helps ensure success in the selection process. 

To properly size a filter element and housing, two basic but very important pieces of information about your equipment are required:

  • Maximum Flow capacity
  • Maximum allowable pressure differential

Using this crucial information, the appropriate sizing can be determined based on filtration media type and allowable velocity through the  media. The minimum connection for the housing connection can also be determined based on flow requirements. High velocities through your filtration media or housing connection can significantly affect filtration performance and pressure drop. Generally, slower air velocity through a media delivers higher filtration efficiency and lower pressure drop across the filter element. A properly sized filter is essential for optimizing an air system’s performance and should be considered early in your design phase for any pneumatic or vacuum system.


Polyester Media Filter Cartridge

Polyester Media Filter Cartridge Rated at 99%+ Removal Efficiency for 5-Mircon.


The following are the key concerns in specifying the optimally sized filter for your industrial application.

#1: What are my filtration requirements?Selecting a Filter Media.

Always begin the selection process by identifying the appropriate media and filter element size based on the following requirements: filtration level, pressure drop, temperature, and chemical compatibility. Solberg manufactures air filter-cartridges using a variety of standard and specialty medias designed to meet specific requirements relating to operating conditions, type of contaminant, removal efficiency, and micron rating.

Note: Indicating an efficiency level with a specific micron requirement is essential to choosing the right media; stating the need for a “1-micron filter” is incomplete without the efficiency rating. For example, a 5-micron filter with 99% filtration efficiency is adequate for most general duty industrial applications. Follow the suggested *Air-to-Media ratios for the external environment conditions and filtration efficiency needs. 


#2: How will process contaminants affect the life of my filter? Selecting a filter-cartridge size.

Contaminant level and type can significantly impact the life of your filter and the level of maintenance required for your equipment. As a filter stops the contaminants from entering the equipment, the filter element begins to load or clog with contaminant and the pressure differential steadily increases until a terminal pressure differential is reached. At this point, the filter element must be replaced.

Solberg’s published flow rates for elements takes filter-life into consideration and provides a reasonable maintenance interval for most general-duty industrial applications. When exposed to harsh operating conditions, it is recommended to select larger filter elements with a greater surface area. Larger filter elements can significantly prolong the life of your filter and extend the maintenance intervals for your equipment.

#3: How do I determine the connection size for my filter-housing? Selecting a filter-housing size.

After selecting the appropriate filter media (#1) and element size (#2), the appropriate housing for your filter element must be determined. As a best practice, match the connection size of your filter housing to that of the equipment being protected or the pipe size of the application’s plumbing - this will help in minimizing pressure differential contributed by the filter housing. While it is acceptable to select a larger connection size, downsizing a connection which is smaller than the pipe size should be avoided.


Filter Silencer (FS Series) with hex fitting connection and carbon steel housing.


Becoming a Filtration Expert.

Understanding how flow and pressure drop influence sizing and selection is the first step to building your knowledge-base and becoming a filtration expert.  There are many other important variables that must also be considered when selecting the best filtration solution for an application’s unique operating conditions - temperature, pressure, type of contaminant, moisture level, and more. Specific requirements such as materials of construction, design codes, and installation will also significantly influence the selection process.

Sound overwhelming? Enlist the experts when you need assistance!

Solberg Filtration is a leading manufacturer in vacuum filters, filter silencers, separators, and oil mist eliminators for compressors, blowers, vacuum pumps and power generation. Feel free to contact us regarding your filter sizing concerns as well as any other technical inquiries.

Learn more about our large variety of replacement filter elements, industrial filtration products, and customer case studies by visiting our website at


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