ISO 29461 is an internationally recognized standard for air intake filters in gas turbines. It has been launched to address the need for a globally harmonized standard for air intake filters specifically designed for gas turbines and turbomachinery. The standard provides a uniform, objective, and comprehensive framework for evaluating, classifying, and comparing air intake filter performance, ensuring the reliability, efficiency, and longevity of gas turbines.
ISO 29461 (all parts) provides a way to compare these products in a similar way and define what criteria are important for air filter intake systems for rotary machinery performance protection. The aim is to compare different filters and filter types with respect to the operating conditions they finally will be used in. For instance, if a filter or a filter system is meant to operate in an extreme, very dusty environment, the real particulate efficiency of such a filter cannot be predicted because the dust loading of the filter plays an important role. A further part of ISO 29461 will address the performance of cleanable and surface loading filters. Filters in turbo-machinery applications can also face very harsh operating conditions such as high air flow rates or water and salt ingress. Further parts of ISO 29461 will address the performance of filters under such harsh conditions.
Parts
ISO 29461-1:2021 – Specifies methods and procedures for determining the static performance of particulate air filters. Related to Efficiency & Dust Holding Capacity
ISO 29461-2:2021 – specifies general test requirements, the test rig and equipment, the test materials and the test procedure and report for determining water endurance performance of Air Filter
The launch of ISO 29461 was driven by several factors:
- Increasing demand for cleaner and more efficient energy production: As the global focus on clean energy production and energy efficiency has intensified, gas turbines have become an essential component of power generation systems. High-quality air intake filters are critical for protecting gas turbines from contaminants, which can cause erosion, fouling, and corrosion, leading to reduced efficiency and premature failure.
- Need for consistency in filter performance, quality, and testing: Before the introduction of ISO 29461, there was a lack of uniformity in the test methods and performance criteria for air intake filters in gas turbines. This made it difficult for manufacturers, operators, and end-users to compare filters and select the most appropriate solutions for their specific applications.
- Technological advancements in filter materials and designs: The development of new filter materials and designs necessitated a standardized testing and classification system that could accurately reflect the performance of these advanced filters in gas turbine applications.
- Facilitating global trade and competition: A globally recognized standard like ISO 29461 enables manufacturers, operators, and end-users to easily compare and select air intake filters based on standardized performance criteria. This fosters competition and innovation in the industry and promotes global trade.
By providing a comprehensive and robust framework for evaluating and comparing air intake filters, ISO 29461 helps ensure the optimal performance, reliability, and longevity of gas turbine systems, contributing to cleaner and more efficient energy production.
The standard was developed in response to the growing demand for cleaner, more efficient energy production and the need for a globally harmonized standard to ensure consistency in filter performance, quality, and testing.
Recent Updates
In 2021, ISO 29461 underwent a revision, the revision aimed to improve the standard’s clarity, scope, and applicability, taking into account advancements in filter technology and the increasing demands of gas turbine applications. As a result, ISO 29461 now provides a more comprehensive and robust framework for evaluating and comparing air intake filters.
New Filter Classes
The ISO 29461-1:2021 classification has filter classes from T1 to T13
T1 – T9 Classes are tested per ISO 16890
T10 – T13 Classes are tested per ISO 29463
Procedure of the Test According to ISO 29461
The testing procedure according to ISO 29461 is designed to evaluate the performance of air intake filters under controlled conditions, simulating the operating environment of gas turbines. The testing procedure encompasses three main parts: ISO 29461-1, ISO 29461-2, and ISO 29461-3.
ISO 29461-1: Test Methods
ISO 29461-1 outlines the test methods for determining the performance of air intake filters, including:
a. Gravimetric efficiency test: This test evaluates the filter’s efficiency in removing particulate contaminants by measuring the mass of dust retained by the filter, which is then used to calculate the efficiency.
b. Dust holding capacity test: This test assesses the filter’s ability to retain dust particles over time, measuring the mass of dust captured before reaching a predefined pressure drop.
c. Differential pressure test: This test measures the initial pressure drop across the filter at a specified airflow rate, which is crucial in determining the filter’s effect on the overall pressure and energy consumption of the gas turbine system.
2. ISO 29461-2: Test Methods
ISO 29461-2 focuses on testing the filter’s ability to remove water droplets, which is critical for applications in humid or wet environments. The test procedure involves:
a. Generating a controlled aerosol of water droplets with a known size distribution and concentration.
b. Measuring the water droplet concentration upstream and downstream of the filter.
c. Calculating the water droplet removal efficiency based on the difference in droplet concentration before and after the filter.
By following the testing procedures outlined in ISO 29461, manufacturers can accurately determine the performance of their air intake filters, ensuring compliance with the standard’s requirements and promoting reliability, efficiency, and longevity in gas turbine systems.