ISO 29461-3 the first international standard for turbomachinery air intake filter mechanical integrity

ISO 29461-3 is the first international test standard for reporting the mechanical integrity of turbomachinery air intake filters under high pressure. It measures a filter’s ability to maintain its form without rupturing under high pressure, ensuring optimal performance, durability, and safety — even in the harshest conditions.

A filter failure can cause catastrophic, irreversible damage to gas turbine components. ISO 29461-3 provides a rigorous, objective testing method to certify filters that can withstand high-pressure environments and prevent such failures.

Why ISO 29461-3?

Protection against foreign object damage (FOD)
The burst strength test ensures no parts of the filter break off or are released downstream during high pressure, which is critical for protecting gas turbines from damage.

Long term durability
This standard also confirm a filter can handle continuous or cyclical pressure loads without failure, by assessing its long-term durability and structural integrity.

Objective and rigorous testing
Before this standard, there was no uniform method for testing a filter's mechanical strength or measuring its damage. ISO 29461-3 introduces the rigorous wet burst test to assess a filter's tolerance to high pressure drop when exposed to moisture. It also establishes an objective pressure drop standard to quantify the damage caused by the test.

ISO 29461-3 test method

Does the filter withstand the burst test, and does it pass or fail the ISO 29461-1 efficiency test afterwards?

Step 1: Efficiency test

Confirm filter initial efficiency per ISO 29461-1

Step 2: Burst test

Spray with water and dust until 25” w.g. / 6250 Pa

Step 3: Failure modes

Ensure there are no loose pieces downstream (FOD risk)
Monitor for sudden reduction in filter pressure drop (massive media tears)
Test the reduction in efficiency after the filter has been affected by the burst test

ISO 29461-1, ISO 29461-2 & ISO 29461-3

When selecting filters, it's essential to consider three key ISO standards:

ISO 29461-1 for filtration efficiency
ISO 29461-2 for hydrophobicity
ISO 29461-3 for mechanical integrity

Camfil recommends final filters that are high-efficiency (T10+) in accordance with ISO 29461-1:2021, and demonstrate strong mechanical durability under high pressure as per ISO 29461-3:2024. For applications exposed to high moisture levels, hydrophobic filters with a low and stable pressure drop, certified to ISO 29461-2:2022, are recommended, in addition to the other two certifications.