Solid particulate
Ambient dust drawn in by the compressor, rust and scale shed by the piping, and debris from degraded filter media. It erodes seals, clogs nozzles and contaminates product.
ISO 8573-1:2010
Compressed Air Quality Audit to ISO 8573-1
We measure particles, moisture and oil in your network and classify every point against the standard.
Compressed air quality is not declared, it is measured. This audit takes readings at the points that actually matter in your system and translates the results into the ISO 8573-1:2010 classification, so you know what air each process is receiving and what needs to be corrected.
Investment
USD $2,500 for 3 sampling points
+ USD $500 per additional sampling point
Prices in US dollars, before tax. Travel and special access requirements are quoted separately depending on location.
What the audit includes
- Walk-through of the system and definition of the sampling points together with your maintenance team.
- Particle counting by size range at every agreed point.
- Pressure dew point measurement and verification of liquid water presence.
- Oil vapour measurement and assessment of total oil content.
- Line pressure and temperature logging at each point to contextualise the readings.
- Assignment of the corresponding ISO 8573-1:2010 [A:B:C] class for each measured point.
The equipment we measure with
Measurement is carried out with portable equipment brought to your plant and connected to the network through an in-line sampling section. It requires neither stopping production nor dismantling pipe runs, provided a sampling connection is available at the agreed point.
- In-line sampling section with a regulating valve, so the sample is taken at actual operating pressure.
- Readout instrument that logs the measured values at each point.
- A set that moves between sampling points within the same visit.
- Set-up and removal with no cutting or welding on your network.
What is inside your compressed air
A compressor does not generate clean air: it compresses ambient air along with everything it carries, and the network adds more downstream. ISO 8573-1 groups that contamination into three families.
Water and humidity
Atmospheric air enters saturated with vapour. Compression and cooling make it condense inside the network. It is measured as pressure dew point (PDP) and, where condensate exists, as liquid water.
Total oil
The sum of aerosol, liquid oil and oil vapour. It comes from compressor lubricant and also from hydrocarbons in the intake air, so an oil-free compressor does not by itself remove this risk.
How an ISO 8573-1 class is written
First the standard, then the revision, then the three purity classes separated by colons.
ISO 8573-1:2010 [A:B:C]
- A
- Purity class for solid particulate
- B
- Purity class for humidity and liquid water
- C
- Purity class for total oil (aerosol, liquid and vapour)
Example: an ISO 8573-1:2010 Class 1:2:1 specification requires, per cubic metre of air, no more than 20,000 particles of 0.1 to 0.5 µm, 400 of 0.5 to 1 µm and 10 of 1 to 5 µm; a pressure dew point of −40 °C or better with no liquid water; and a maximum of 0.01 mg of total oil.
Class 0: what it actually means
- It does not mean zero contamination.
- It does not mean oil-free air.
- It does not refer only to oil: it applies to any of the three contaminants.
- It must be stricter than Class 1 for the chosen contaminant.
- It requires the agreed numeric value and the contaminant it applies to be stated in writing.
- A compressor sold as "Class 0" does not by itself guarantee oil-free air at the point of use.
ISO 8573-1:2010 purity classification table
Maximum values allowed per cubic metre of compressed air at the standard reference conditions. This is the scale each audited point is compared against.
| Class | 0.1 – 0.5 µm | 0.5 – 1 µm | 1 – 5 µm | Mass mg/m³ | Dew point | Liquid water g/m³ | Total oil mg/m³ |
|---|---|---|---|---|---|---|---|
| 0 | As specified by the equipment user or supplier, and more stringent than Class 1. | ||||||
| 1 | ≤ 20,000 | ≤ 400 | ≤ 10 | — | ≤ −70 °C | — | 0.01 |
| 2 | ≤ 400,000 | ≤ 6,000 | ≤ 100 | — | ≤ −40 °C | — | 0.1 |
| 3 | — | ≤ 90,000 | ≤ 1,000 | — | ≤ −20 °C | — | 1 |
| 4 | — | — | ≤ 10,000 | — | ≤ +3 °C | — | 5 |
| 5 | — | — | ≤ 100,000 | — | ≤ +7 °C | — | — |
| 6 | — | — | — | ≤ 5 | ≤ +10 °C | — | — |
| 7 | — | — | — | 5 – 10 | — | ≤ 0.5 | — |
| 8 | — | — | — | — | — | 0.5 – 5 | — |
| 9 | — | — | — | — | — | 5 – 10 | — |
| X | — | — | — | > 10 | — | > 10 | > 10 |
Particle columns: maximum number of particles per m³ in each size range. "Mass": particulate mass concentration. "Dew point": water vapour pressure dew point. "Total oil": aerosol, liquid and vapour combined. "—" means the standard defines no value for that combination.
The ISO 8573 series in nine parts
Part 1 defines the purity classes. Parts 2 to 9 define how each contaminant is measured, and are what gives a result its technical validity.
ISO 8573-1:2010
Compressed air purity classes (contaminants allowed per m³)
ISO 8573-2:2018
Test method for oil aerosol content
ISO 8573-3:1999
Test method for humidity measurement
ISO 8573-4:2019
Test method for particle content
ISO 8573-5:2001
Test method for oil vapour and organic solvent content
ISO 8573-6:2003
Test method for gaseous contaminant content
ISO 8573-7:2003
Test method for viable microbiological contaminant content
ISO 8573-8:2004
Test for solid particle content by mass concentration
ISO 8573-9:2004
Test method for liquid water content
Deliverables
- 1Technical report with the ISO 8573-1:2010 [A:B:C] class obtained at each sampling point.
- 2Comparison table between the measured class and the target class for your application.
- 3Identification of out-of-spec points and their probable cause.
- 4Filtration, drying and drainage recommendations prioritised by impact and cost.
- 5Photographic record and location of every sampled point.
- 6Results review session with your team, on site or remote.
Typical applications
- Food and beverage
- Air in direct or indirect contact with product and packaging.
- Pharmaceutical and medical devices
- Process air in controlled areas.
- Automotive and metalworking
- Painting, blow-off, pneumatic tooling and automation.
- Electronics
- Clean dry air (CDA) systems for assembly and test.
- Plastics and packaging
- Bottle blowing, pneumatic conveying and moulding.
- Instrumentation and control
- Instrument air, valves and critical actuators.
Audit pricing
Base package
USD $2,500
3 sampling points
Additional point
USD $500
per extra point
Prices in US dollars, before tax. Travel, waiting time and special access or safety requirements are quoted separately depending on plant location.
Frequently asked questions
What is a sampling point?
Each physical location in the network where a sample is taken: compressor outlet, downstream of the dryer, an area header or a critical point of use. The ISO 8573-1 class is assigned per point, not to the whole system.
How many points do I need?
It depends on the size of the network and how many different air qualities coexist in it. The base package covers three points, usually enough for one line or area. Plants with several critical processes normally need additional points.
How long does the on-site work take?
Field work for the base package is normally completed in a single day. The actual time depends on access to the points, plant permits and how stable operation is during measurement.
What does Class 0 mean?
Class 0 does not mean zero contamination or oil-free air. It is a customised class that must be stricter than Class 1, state which contaminant it refers to, and declare the agreed numeric value in writing. Without that value the claim does not comply with the standard.
Is this audit an accredited certification?
No. We deliver a technical measurement report with the ISO 8573-1:2010 classification obtained at each point and the associated recommendations. We do not issue certificates under the accreditation of a certification body.
Is breathing air covered?
No. ISO 8573 does not cover breathing air requirements. For that use, the breathing air standards in force in the country of installation must be applied.
What air class are you delivering today?
Tell us how many sampling points you need and we will confirm scope, date and final price.