Filter Design Considerations

There’s a lot to consider when it comes to filters and filter design, especially in the Aerospace, Defense and Marine industries. Through a wide range of   aircraft and land vehicles, to  the extremes of aerospace applications, nuclear submarines, and test/maintenance facilities, companies depend on quality filters to perform under and withstand the most demanding conditions.

There are many different filter types to keep in mind when deciding on the right one, these include:

  • Air filters & screens
  • Hydraulic fluid filters
  • Lubricant & oil filters
  • Fuel filters
  • Water & steam filters
  • Specialized filters

Your considerations should be based on the application and the type of filter you need, but variations in design and material means some types are more beneficial for specific applications or industries.

Air filters & screens

Some of the biggest aircraft and Naval vessels in the world have utilized our air filters and screens, such as the US Navy DDG 51 destroyers, F-4A fighters, and Boeing 707’s and 727’s. Our air filters and screens come in five different designs/materials:

  1. Pleated media & sintered metal fabric: This component offers superior dirt-loading capacity and trap. It’s also capable of removing particles ranging from 3-150 microns in size.
  2. Perforated metal screen (strainers): These screens have a minimum blocking capacity of 250 microns, and offer outstanding strength in many different configurations.
  3. Sintered metal media: Self-supporting with casting properties, this media can withstand high temperatures and captures particles down to 1 micron or smaller (dependent on design). These are manufactured in conjunction with industry leading sintering suppliers.
  4. Woven wire mesh: These are available in a large variety of weave combinations and are cleanable and reusable. Woven wire mesh can trap contaminants from 5-250 microns in size.
  5. Non Metallic media: In some cases, fabric, fiberglass or plastics can provide more effective filtration that woven mesh. Applications that require high dirt holding or extra fine particle retention are good examples. FCP specializes in metallic media, but can use these materials as needed to meet your needs.

Hydraulic fluid filters

Most Hydraulic filters come in different varieties and are used in a variety of applications.

For military applications, some examples include:

  • F-8 & F-104 fighter jets implement a specially designed sintered bronze filter for their hydraulic systems. Our high-pressure filters are also used in Pratt & Whitney (PT6 series) and GE engines designed for a multitude of commercial and military aircraft.
  • Our hydraulic filters aid in the functionality of the CH-47 “Chinook” helicopter’s control system.
  • We also provide support to other applications, including the AIM-9L Sidewinder missile and the M109A6 mobile Howitzer.

In terms of military projects, one of our crowning achievements has been for the Navy. They use a disposable hydraulic filter on the controllable pitch propeller hydraulic system onboard DD963 (Destroyer) class ships. By using our replaceable filters, the Navy has increased its operating cycle for these ships by a factor of four because of the enhanced dirt-loading capability.

Here’s a breakdown our Tee and ELL type hydraulic filters:

Filters for hydraulic systems

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Filters for Hydraulic Systems

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Lubricant & oil filters

Performance data indicates that filters used in lube and oil filtering applications fall within the following performance boundaries (this is not a specific combination):

  • Working pressures to 3000 psig (207 bar)
  • Element collapse pressures up to 1000 psig (69 bar)
  • Particle retention down to 3 microns
  • Flow rates up to 38 gpm (0.14m3/min)
  • Temperature range of -65°F to 700°F (-54°C to 371°C)

FCP can easily work outside these typical parameters when you need it.

Our lubricant and oil filter designs include:

  1. Pleated wire cloth: These withstand very high differential pressures and temperature extremes. The cloths can be woven from a variety of materials, and either pleated or non-pleated. They can be welded, brazed, or epoxied according to requirements; and they’re cleanable, with a minimum absolute filtration rating of five microns.
  2. Stacked disc filters: Suited for high viscosity liquids, stacked disc filters protect at high pressure differentials and flow rates, and provide depth filtrations resulting in elevated dirt-loading capacity. For added ease, they are very easy to service.
  3. Perforated metal & wire mesh strainers: These are capable of trapping contaminants 100 microns or larger, and magnets can be incorporated to remove metallic debris. Their key design parameters include flow rate, pressure drop, and particle size. FCP offers these in a variety of sizes and shapes, and configurations suit customization from a 1/8” fitting to a 6’ tall unit.
  4. Sintered metal media: Sintered metal media can withstand higher pressures than non-metallic filter elements, and are self-supporting with versatile casting properties.

Fuel filters

Our fuel products come in a variety of designs, as previously mentioned. These include:

  • Perforated Metal & Wire Mesh Strainers
  • Pleated Wire Cloth
  • Pleated Non-Metallic Media
  • Sintered Metal Media

The Lockheed C-130, MQM-107 Subsonic Target Drone, and space shuttles have all had to rely on fuel or liquid hydrogen fuel filters. Most of our filters used in fuel filtration applications fall within the typical performance parameters listed below, but FCP can work with you to create something beyond these parameters:

  • Working pressures up to 1000 psig (69 bar)
  • Element collapse pressures up to 250 psig (17 bar)
  • Particle retention down to 3 microns
  • A wide range of flow rates

It is possible to work outside these characteristics when requested. Good engineering can lead to designs that  exceed industry standards, according to a client’s design requirements.

Final considerations

Perhaps the biggest consideration for your filters should be the qualifications of the manufacturer. As a company that strives to maintain its certifications and approvals, FCP knows how important it is to provide clients with parts that are backed by fully compliant designs. The filter or screen you go with will determine how well your equipment operates. Your filter should support your designs by optimizing efficiency and performance, so that it not only exceeds your expectations, but your company or client’s’ expectations as well.