Common Tests for Aerospace Filtration Systems

Aerospace programs depend on filtration components that function reliably under wide variations in pressure, temperature, flow rate and particulate load. Every filter installed in a hydraulic, pneumatic or oxygen system must pass defined test methods before it is approved for use in an aircraft or launch vehicle.

This guide outlines the common tests for aerospace filters and how these established procedures confirm the performance, structural integrity and material compatibility of the elements.

Why Aerospace Filtration System Testing Is Critical

Here are numerous reasons why aerospace filtration system testing is a fundamental requirement during the development and procurement of various aerospace platforms:

• Protecting critical components: Testing verifies that filters can consistently remove damaging particulates and support uninterrupted operation, which helps safeguard components such as hydraulic actuators, propulsion components and oxygen delivery systems.
• Meeting industry standards: Aerospace filters must meet rigorous global standards, including ISO, ARP and ASTM specifications. These standardized tests provide measurable benchmarks for performance, durability and safety, ensuring filters are qualified for aerospace deployment.
• Preventing costly failures: Testing aerospace filtration systems reduces the risk of system erosion, valve sticking, sensor malfunctions and fluid degradation, which can cause catastrophic failure.
• Extending equipment life cycles: Well-tested filters contribute to longer service intervals for mission-critical systems by reducing contamination-related wear and improving fluid cleanliness over time.
• Validating performance claims: Engineers and procurement teams rely on test data to match filters with specific flow rates, pressure conditions and particulate profiles.
• Supporting system selection and integration: Data from quality tests for aerospace filtration systems helps engineers compare filter media, assess pore structures and match components to hydraulic, pneumatic and oxygen systems during design.
• Verifying material compatibility: Compatibility tests confirm that filter elements will perform safely with various aerospace fluids, including petroleum oils, synthetic blends, water-glycol solutions and oxygen.

The following aerospace filter tests are widely used across commercial aviation, military aircraft, spacecraft, launch vehicles and ground‑support systems.

Performance and Efficiency Tests

Performance testing examines how a filter behaves during normal and elevated operating conditions.

Separation Efficiency, ISO 14085-3:2024

This test measures a filter’s ability to separate contaminants from a fluid stream. It introduces a controlled particulate distribution upstream and analyzes downstream results to calculate efficiency at specific micron sizes. Maintaining high separation efficiency is essential to protect valves, actuators and sensors from wear or blockage.

Dirt-Holding Capacity, ISO 16889:2022

The dirt-holding capacity test determines the amount of contaminant a filter can retain before its performance degrades. The process involves continuously injecting test particulates into the fluid stream while measuring downstream particulate levels to determine the element’s efficiency.

The filter’s maximum dirt-holding capacity is the amount of dirt it can retain without compromising filtration quality. This data is critical when selecting filters for extended missions or remote applications where maintenance intervals are long.

Differential Pressure vs. Flow

This test gauges the pressure drop generated by the element at various flow rates and viscosities as outlined in ISO 3968. The characteristic curve produced by this test allows engineers to evaluate how a filter behaves as system flow fluctuates. Consistent performance across the entire curve is vital for aerospace hydraulic and pneumatic circuits.

Thermal Flow

Filters used in aerospace systems undergo wide thermal variations, especially in high-altitude conditions or during rapid equipment cycling. This test verifies performance across the allowable temperature range and identifies the temperature at which flow resistance begins to increase. It’s vital for oxygen and hydraulic filters operating near their temperature limits.

High-Flow Testing

High-flow testing simulates the extreme flow demands encountered in rocket propulsion and other high-velocity aerospace systems. The test measures how a filter behaves as volumetric flow increases, including changes in pressure drop, media stability and overall flow capacity.

Hydraulic Fluid Power, ISO 16889

ISO 16889 defines the multi-pass method used to assess efficiency and particulate capture under continuous contamination. The test introduces a controlled contaminant stream into hydraulic fluid as it circulates through the filter. Particle counters measure upstream and downstream concentrations to determine the efficiency at specified micron sizes.

Structural Integrity and Durability Tests

These aerospace filtration system tests assess structural strength, endurance and overall physical reliability.

Pressure Differential, ISO 2941

ISO 2941 provides the method for measuring collapse and burst resistance. The filter is exposed to increasing differential pressure until it can no longer maintain structural integrity. This test confirms that the housing and element can tolerate the highest expected differential pressure levels in hydraulic and aerospace fluid systems.

Flow Fatigue Resistance, ISO 3724

ISO 3724 evaluates how well the element tolerates repeated flexing caused by cyclic flow. The test exposes the filter to thousands of flow cycles at a defined terminal differential pressure. This procedure is crucial for aircraft hydraulic systems that frequently require rapid actuation and directional flow changes.

Bubble Point, ARP901

A bubble point test measures the absence of bubbles to verify the integrity of a filter element. It also identifies the filter element’s first bubble point to locate its largest pore. This test applies gas to the filter’s wet side to measure the minimum applied pressure necessary for fluid to flow through the pores.

Material Compatibility and Safety Tests

Material compatibility tests evaluate the behavior of seals, adhesives, housings and element media when exposed to various fluids at extreme temperatures and pressures.

Fluid Compatibility

This test confirms that the filter materials maintain their structure when exposed to approved aerospace fluids, such as:

• Water-glycol blends
• High water base fluids
• Petroleum-based oils
• Synthetic lubricants
• Oil-water emulsions

Cryogenic Sealing and Helium Leak

Cryogenic sealing tests validate filter performance at extremely low temperatures. The assembly is submerged in liquid nitrogen until all materials reach a uniform soak temperature. A helium leak test then measures seal integrity at that temperature. This evaluation is essential for systems used in high-altitude aircraft and space applications where cryogenic conditions are common.

Ignition, ASTM G175 for Oxygen

ASTM G175 evaluates whether a filter remains stable and nonreactive when exposed to high-pressure oxygen and potential ignition sources. This test is crucial because it verifies that a filter is safe and will not ignite under any conditions.

Partner With Chase Filters & Components to Ensure Aerospace Reliability

Aerospace programs require components that are validated through repeatable, high-standard testing. Every filter used in flight, ground support or propulsion systems must perform as expected under thermal stress, pressure cycling and variable flow.

Chase Filters & Components develops filtration solutions engineered for this level of responsibility. Our high-pressure housings and precision-built elements support aerospace applications that demand consistent performance across thermal extremes, dynamic flow cycles and elevated operating pressures.

Our products, such as the 51 Series, 31 Series and 25 Series, are built for these conditions, giving engineering teams options supported by more than three decades of filtration expertise and a track record of successful testing.

Contact our engineering team to discuss your application or explore our full range of high-performance aerospace filters.