Compressed Air Quality Testing

Compressed air is used in more than 70% of manufacturing processes, and in industries such as food, beverage, pharmaceutical and medical device production it often comes into direct contact with the product. If that air is carrying particulate, water or oil, the contamination goes straight into your process.

IATT tests compressed air quality to ISO8573-1 (BS EN 12021:2014 Respiratory protective devices) at your point of use, so you know what your system is actually delivering rather than what it was specified to deliver. Our factory trained engineers are located throughout the UK, all test equipment is fully calibrated and certified, and a full report is issued for every test point.

What Our Compressed Air Quality Testing Service Includes

Testing is non-invasive and can be carried out during normal working hours, with multiple test points covered in a single visit.

• On-site testing at your point of use, not just at the compressor
• Testing to ISO 8573-1:2010 for solid particulate, water and oil
• Compressed air, compressed nitrogen and compressed oxygen
• Clean room atmosphere particle testing and oxygen atmosphere testing
• A full test report for every test point
• Advice on filtration, drying and pipework if a test point fails
• Repeat testing scheduled around your audit and maintenance cycles

Your report will indicate all the readings taken, including compressed gas pressure, system pressure, ambient temperature, oil mist, carbon monoxide, water vapour, dewpoint, oxygen, odour and particulate. Each one cross-references the serial numbers of the test equipment used against the relevant calibration certificates, so your results are fully traceable when an auditor asks for them.

What We Test For

ISO 8573-1 splits compressed air purity into three categories, and we test all three.

Solid particulate (ISO 8573-4) enters your system as atmospheric dirt and is generated inside it by pipe scale, wear particles and deteriorating O-rings and gaskets. We use a calibrated laser particle counter that measures down to 5µm, 0.7µm, 0.5µm and 0.3µm, with results available on site in around ten minutes. Sampling at the point of use matters here, because flexible hoses and tubing fitted after your point of use filters can shed particles of their own. Air that tests clean at the header can still fail at the nozzle.

Water (ISO 8573-3) is drawn in through the compressor intake as vapour and makes up the largest share of contamination in most systems by volume. We measure pressure dewpoint or atmospheric dewpoint using a calibrated portable hygrometer, which gives an instant, traceable figure. Left uncontrolled, moisture corrodes pneumatic equipment, shortens filter life and creates the conditions bacteria need to grow.

Oil (ISO 8573-2) is tested as total oil content, covering liquid, aerosol and vapour, and is reported in parts per million. We use chemical detection tubes and oil impactor sampling. Vapour is the fraction most often missed, as it can still be present after the liquid and aerosol content has been filtered out, which is why oil free systems are worth verifying rather than assuming.

ISO 8573-1 does not classify microorganisms. If your process calls for microbiological sampling, take a look at our bacteria testing service.

Understanding ISO 8573-1 Purity Classes

ISO 8573-1:2010 is the international standard for compressed air purity. Introduced in 1991 and now in its third edition, it gives everyone involved a common language, from the compressor manufacturer and filter supplier through to the end user and the testing engineer. A fourth edition is currently in development and we will test to it as soon as it is published.

The standard covers particles, water and oil, with each contaminant having its own range of purity classes. It does not include classes for gases or microorganisms.

Compressed air used for breathing is a separate matter, covered by BS EN 12021:2014, Respiratory equipment, compressed gases for breathing apparatus. This sets its own limits for carbon monoxide, carbon dioxide, water and oil rather than using the ISO 8573-1 purity classes. If you supply air to breathing apparatus or air fed masks, whether that is in a spray booth or on a production line, it needs testing to BS EN 12021:2014 rather than ISO 8573-1. We test to both standards and can cover your process air and your breathing air in the same visit. See our breathing air systems page for more.

How ISO 8573-1 Purity Classes Are Written

A designation is written as the standard name and edition date, followed by the three class numbers in brackets, separated by colons.

ISO 8573-1:2010 [P:W:O]

• P is the purity class for particles (classes 0 to 7, or X)
• W is the purity class for water (classes 0 to 9, or X)
• O is the purity class for oil (classes 0 to 4, or X)

The standard itself uses the letters A, B and C, but P, W and O makes the order easier to remember.

ISO 8573-1:2010 [2:2:1] indicates class 2 for particles, class 2 for water and class 1 for oil. Where a contaminant has not been classified, the class number is replaced with a hyphen, so ISO 8573-1:2010 [2:-:1] indicates that water is not classified.

Class 0 is the designation most often misunderstood. It does not mean there are zero contaminants. When specifying air quality to class 0, a limit must be included in the designation and it must be more stringent than class 1. ISO 8573-1:2010 [1:2:0 (0.001)] indicates class 1 for particles, class 2 for water, and class 0 for oil with a limit of 0.001 mg/m³. If you are requesting filtration or analysis to class 0, always provide a limit tighter than class 1.

Get in touch today to chat to one of our experienced and knowledgeable staff who can help with any technical or other queries you might have. Request a free quote – we’re happy to help.

Compressed Air Quality Testing FAQs