New EN779:2012 Standard for Air Filters Helps Turbine Operators Compare Filter Elements

The new European standard for air filters (EN779:2012) comes into force in the summer of 2012. Its purpose is to classify air filters based on their minimum filtration efficiency (ME) on 0.4μm particles. The new standard will help eradicate a number of problems related to filter performance and help turbine operators to compare replacement filters for their air inlet system.

Gas turbine inlet filter systems have during the past 10-20 years typically been designed with G4 pre-filtration and F7-9 (EN 779) final stage efficiency in static systems. This has provided an acceptable engine protection for many installations, but with an increasing use of gas turbines in urban environments, engine degradation is sometimes rapid and water wash cycles is often reduced to a few hundred hours.

Operators are now becoming increasingly aware of this situation and tend to request filter elements that better protect their gas turbines and make sure they can operate at designed efficiency for longer periods without unplanned shutdowns. This has put filter life time performance in the spotlight and has created a demand for test reports that better reflect how filters work in real life.

Elements that better protect their gas turbines and make sure they can operate at designed efficiency for longer periods without unplanned shutdowns. This has put filter life time performance in the spotlight and has created a demand for test reports that better reflect how filters work in real life.

The new European standard for air filters (EN779:2012) comes into force in the summer of 2012. Its purpose is to classify air filters based on their minimum filtration efficiency (ME) on 0.4μm particles. The industry has now voted for tougher requirements for air filters and national versions will be available in mid-July, after which the former standard will no longer apply. The new standard will help eradicate a number of problems related to filter performance.

One of these problems is associated with electrostatic-charged synthetic filters. To pass a lab test, these filters usually demonstrate good initial filtration efficiency while they keep their charge, but tend to discharge extremely rapidly, often after just a few weeks of operation. F9 performance in the lab for an electrostatic-charged filter can therefore decrease to F6 in real operating conditions, and sometimes even more. Their cleaning ability deteriorates considerably as a result.

By basing classification on an ME of at least 70% for F9 after discharge, the new EN779:2012 standard will force these filters out of the market.

It is important to understand the complexity of differentiating air filters. Most air filters will remain in a system for months or even years. However, testing of these filters often occurs in a few minutes or hours. During its life, an air filter will see dozens or hundreds of environmental changes such as temperature, humidity, air flow velocity and particle load.

Camfil Farr has invested in a full scale climate chamber used to evaluate filtration needs under difficult circumstances. In our air filter testing laboratories we can modify all the important parameters such as airflow, relative humidity and salt content.

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