ISO 12500 – simplifying compressed air filter selection
October 26th 2007 When selecting compressed air purification equipment, installers and users often compare the performance of equipment from many manufacturers in an effort to cost effectively achieve the quality of compressed air required by their application. Mark White, product manager of domnick hunter - a division of Parker Hannifin explains what to look for when benchmarking compressed air purification products.
For many years, manufacturers of compressed air purification equipment have used the purity classifications of ISO 8573.1 to rate the delivered air quality of their products. Unfortunately, the ISO 8573 test methods were primarily developed to verify air quality in a compressed air system, not to test purification equipment, therefore not all products claiming compliance with the standards are tested in an identical way. They contain a major omission, one which makes comparison and selection of compressed air filters extremely difficult, if not impossible for the user. The vital piece of information which is missing when testing products is an inlet challenge concentration. So even though different manufacturers claim their products meet a certain purity class, they will most likely have been tested with differing inlet concentrations of contamination. So filter performance which may look similar or even identical on paper, can provide significantly different results when installed in a compressed air system.
A new standard has been introduced to complement the existing ISO 8573 series. The new standard, ISO 12500, will consist of three parts, with ISO 12500.1 covering the testing of compressed air coalescing filters for oil aerosol (liquid) removal, ISO 12500.2 to determine the adsorption capacity of oil vapour removal filters and ISO 12500.3 covering the testing of solid particulate filters. Parts one and two were released in June 2007, with part three to follow.
Testing of coalescing filters
ISO 12500.1 has introduced two challenge concentrations of oil aerosol to be used when testing coalescing filters, these are 40mg/m3 and 10mg/m3. The new standard requires filters to be tested using the existing test method and equipment shown in ISO 8573.2 while using one of the two challenge concentrations. In addition to this, ISO 12500.1 requires filters to be ‘wetted out’ which is representative of an operational filter. Recording of the filters initial saturated pressure drop has also been included, again to give a more accurate and representative indication of the filters operational costs. Three examples of each model requiring validation must be tested and each tested three times. Published performance data is then based on calculating an average of all the tests in order to provide the person selecting a new product with a more representative indication of performance.
For further information, see the next issue of IP&E, or  click here More articles from Parker domnick hunter: | 
