ISO 8573 Air Purity Measurement

What is ISO 8573?
ISO 8573 is a European Standard that describes contaminants in compressed air and defines purity classes for them. This multi-part standard also defines approved measurement methods for testing contamination levels.
ISO 8573-1 states purity classes for the most common contaminants of particles, water and oil and allowing users to work to achieve appropriate compressed air quality levels of 1:2:1 or 1:1:1 for example.
Other contaminants such as gases, VOC’s and microbiologicals are not currently listed against purity classes but methods of measurement are defined in the appropriate section standard.
  • ISO 8573-1: Contaminants & purity classes
  • ISO 8573-2: Oil aerosol test methods
  • ISO 8573-3: Humidity test methods
  • ISO 8573-4: Solid particle test methods
  • ISO 8573-5: Oil vapour test methods
  • ISO 8573-6: Gas test methods
  • ISO 8573-7: Viable microbiological content tests
  • ISO 8573-8: Solid particle test methods by mass concentration
  • ISO 8573-9 Liquid water test methods

Why do I need ISO 8573 Compliant Measurement?

ISO 8573 is an international standard that is effectively a guideline to base your site standards and measurement procedures on. There is no legislation in place to make absolute compliance mandatory across all industries although some industries may have regulatory targets they need to demonstrate compliance with.

It is easy to follow the standard verbatim in theory but there are practical issues that may become more important factors to determine how to monitor compressed air purity.

The minimum compressed air quality necessary or desirable will vary according to the processes involved and areas of plant. The cost of delivering ultra pure air is very high and only needs to be employed where necessary. In effect this gives plant managers a problem of balancing operating costs against site risk assessments and the corresponding penalties with the result that several air quality classes may be appropriate for different areas of plant.

The frequency of testing or monitoring these different classes needs to reflect the potential impact from the risk assessments and should always be reinforced with additional testing whenever any changes are made to the compressed air plant or distribution system.

How do I test against ISO 8573 purity classes?

Once a decision has been made which of the 3 main contaminants and which purity classes are appropriate for a particular plant, the means of testing will be partially determined by the frequency.

Periodic audits, surveys or point tests for particles, water (dew point) and oil (liquid, aerosol and vapour forms) can be achieved through a variety of means. The ISO 8573 standards cover a wide range of test methods involving exposure of diaphragms to the compressed air and subsequent laboratory analysis which is very accurate and the time between test and results may be acceptable, particularly for the lower purity classes.

There are more methods available than are currently described in the standard sections which if employed, may accurately measure according to the purity class limits but are not compliant with the approved methods and as such may not be claimed to give ISO 8573 compliant results.

The ISO 8573 standard approved methods do not cover continuous monitoring methods for all 3 common contaminants and as such, where this is important for high purity systems, a decision has to be made to accept that the testing may be to the class limits but NOT compliant with the ISO 8573 testing methods.

An acceptable method may be to employ continuous testing where necessary and also use compliant periodic testing for verification.:

How to overcome the practical problems of ISO 8573 oil measurement in compressed air

Compressed Air Purity Measurement Products

S600 portable air purity analyser for dew point, particle and oil vapour 

S520 handheld SMART dew point meter.

S120 PID Oil Vapour Sensor

S130 laser particle sensor for portable or continuous duty

S601 continuous air purity analyser for pressure dew point, particle and oil vapour

S605 Portable Breathing Air Analyser

S606 Continuous Breathing Air Analyser

Related pages:

Dew Point   Particle   Oil Vapour  Air Purity            

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