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.
John Davis, Australasian Business Development Manager of Parker domnick hunter, also known domnick hunter , has explained what to look for when benchmarking compressed air purification products and how a new ISO Standard will help provide greater clarity.
New ISO12500 standards help users compare compressed air quality and contamination:
The International Standards Organisation (ISO) has long concerned itself with compressed air quality standards, introducing a series of standards covering the issue back in 1991
Comprising of nine parts, they provide quality classifications for the main compressed air contaminants as well as methods to accurately test for the contaminants.
The primary document of the series is ISO 8573.1, which uses a series of purity classifications to define the maximum amount of contamination allowable per cubic metre of compressed air.
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 and presenting product data in this way should allow users to make easy comparisons about the performance of purification products from different manufacturers.
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.
To accurately detect and measure contaminants in a compressed system and show compliance with the selected purity levels from ISO 8573.1, the equipment and methods shown in ISO 8573 parts 2 to 9 must be used. These test methods can also be used to test the performance of purification equipment. However for this purpose, 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 entering the product and because challenge concentrations are rarely included in technical data, filter performance that may look similar or even identical on paper, can provide significantly different results when installed in a compressed air system.
Introducing ISO 12500 - The International Standard for Compressed Air Filter Testing
The ISO 8573 air quality standards were introduced to assist, not confuse compressed air users, so to overcome the problems associated with product selection, 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.
ISO12500.1 - Testing of Coalescing Filters Coalescing filters are probably the most important items of purification equipment in a compressed air system as they are designed not only to remove aerosols (droplets) of oil and water, but also to remove solid particulate and micro-organisms. For this reason, ISO 12500.1 is of utmost importance.
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 whilst 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. This is a big step in the right direction.
Parker domnick hunter’s Oil-X Evolution aerosol and particulate removal filters been designed to be fully compliant with the new ISO8573.1: 2001 air quality standards as well as the forthcoming ISO12500 standard for filter testing.
Oil-X Evolution has been designed from the ground up with the key design focus concentrated in critical areas such as air flow management, filtration media selection and construction and the efficient removal of coalesced liquid.
In Oil-X Evolution all aspects of cartridge filter design have been considered with the sole purpose of providing compressed air to international quality standards whilst reducing the cost of ownership and the space envelope required for installation.