This part of ISO 29461 specifies general test requirements, test rig and equipment, test materials, test procedure and report for determining water endurance performance of air filter elements used in air intake filter systems for rotary machinery such as stationary gas turbines, compressors and other stationary internal combustion engines. The test evaluates water endurance performance of air filter elements under laboratory conditions. The performance results obtained in accordance with this part of ISO 29461 cannot be quantitatively applied (by themselves) to predict performance in service with regard to water endurance and lifetime.