March 23, 2012

Standard for requirements of air filtering gets updated

Halton F7 air filter exceeds requirements with flying colours

The European standard EN779, which classifies air filters, is being accepted. The updated standard increases requirements, as the minimum filtration efficiencies of fine filters are now defined. Halton has introduced the new F7 air filter, which is of top level in the market as well as in accordance with the standard.

The European standard known as EN779, commonly used in categorisation of air filters, is being updated to EN779:2012. The update specifies the classification criteria and filtering capacity requirements for air filters.

Filters are to be divided into three filtering classes (G1–G4, M5–M6, and F7–F9). In addition, the standard sets minimum collection efficiency and charge elimination requirements for class-F filters, used most commonly as the main filters for indoor air.

Under the standard, the filtration efficiency after charge elimination for an F7-class filter must be at least 35% (particle size: 0.4 µm) throughout the use of the filter, and the average filtration efficiency must be 80–90%. The introduction of charge elimination is aimed at better monitoring of the short-term increase in filtering efficiency accomplished by electrically charging the filter material. This has been common with filters made from synthetic materials. Once the benefit brought about by electrical charging ceases to exist, the filtration efficiency may have dropped significantly, not long after the product’s installation.

Table: Categorisation of coarse, medium, and fine filters Fpr EN779:2011 ^1). 

Halton launches a new F7 filter range

In last September, Halton launched a new family of F7-class bag filters. 'Our aim was to create a filter that would be the most efficient in its class in cleaning air while still being energy-efficient. When it comes to filtering performance, our new F7 filter is at the top level in the markets and in accordance with the classification regulations. Its minimum filtration efficiency is 65% while its average efficiency is approximately 90%. This brings the product’s filtering performance close to the threshold for F8 filtering while the initial pressure loss still remains at a very low level,’ explains Christian Mylius, the man in charge of the development project at Halton.

The high performance figures of the new product have been obtained by improving the filtering characteristics of the filter fabric and developing the aerodynamic features of the air filter so as to allow for optimal air flow through the filter.

‘The ultimate goal of the development project was to develop a product that promotes the well‑being of the users of the building. We are very satisfied with the level we attained for both filtering efficiency and the pressure loss and believe that our product ranks among the best on the market,’ Mylius adds.

Filtration efficiencies compared

In recent years, discussion of the air filtering of a building has shifted largely toward evaluation of energy consumption. ‘When one is selecting filters, it is important to specify the design values and replacement intervals for the products in a maximally energy-efficient way. The pressure loss of the building’s ventilation system is composed of duct, actuator, ventilating machine, terminal device, and air filter effects. The total pressure loss of the system may be in the range of 500–2,000 pascals. When one considers the whole, saving a few pascals at the expense of filtration efficiency is not sensible,’ Mylius explains.

Yet there is room for improvement in the new EN779:2012 standard. The update is a step forward from the previous version, as filtration collection efficiencies are introduced in the F7–F9 classes. However, the new standard has loopholes. ‘We have tested a number of filters that reach collection efficiencies of 55% or 65% at equal pressure losses. In our comparisons, both filters may easily reach the F7 class while the better product has almost 20% better filtration efficiency. When selecting a filter, one should primarily look at the filtration efficiency before and after charge elimination,’ Mylius concludes.

For more information, contact:

Christian Mylius
Technical Manager
E-mail: christian.mylius@halton.com
Tel.: +358 20 792 2200