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 confirms whether a filter can handle continuous or cyclical pressure loads without failure, by assessing its long-term durability and structural integrity.

Objective, rigorous testing
Before ISO 29461-3, there was no standardized method for testing a filter’s mechanical strength or evaluating damage under pressure. This standard introduces a rigorous wet burst test to assess a filter’s ability to withstand high pressure drop in both dry and moisture-laden conditions — and to quantify the damage caused by the test.

ISO 29461-3 test method

Does the filter pass the burst test?

Step 1: Efficiency test

Confirm filter initial efficiency per ISO 29461-1

Step 2: Burst test

Confirm whether the filter can withstand high filter pressure by spraying the filter 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.

*In tough operating environments, gas turbines are exposed to extreme conditions that can cause a high filter pressure drop. This can reduce a filter's particulate efficiency in the field. For example, a filter originally rated as T10 may drop to T8 if damaged during operation. The ISO 29461-3 test standard accounts for these challenges by rating filters based on their ability to maintain efficiency under high water exposure, heavy dust loading, and high pressure drop.

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

Camfil recommends final filters that are high-efficiency (T10+) in accordance to ISO 29461-1:2021 to prevent contaminant bypass. For applications exposed to wet conditions, filters should also be hydrophobic filters according to ISO 29461-2:2022 to prevent water bypass. Finally, filters should demonstrate strong mechanical durability under high pressure as per ISO 29461-3:2024 to ensure safe operations.