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ISO 8573 – COMPRESSED AIR QUALITY STANDARDS

ISO 8573 IS THE GROUP OF INTERNATIONAL STANDARDS RELATING TO THE QUALITY OF COMPRESSED AIR AND

CONSISTS OF NINE SEPARATE PARTS. PART 1 SPECIFIES THE QUALITY REQUIREMENTS OF THE COMPRESSED

AIR AND PARTS 2 – 9 SPECIFY THE METHODS OF TESTING FOR A RANGE OF CONTAMINANTS.

ISO 8573.1 : 2001 is the primary document used from the ISO 8573 series and it is this document which allows the user
to specify the air quality or purity required at key points in a compressed air system.
Within ISO 8573.1 : 2001 purity levels for the main contaminants are shown in separate tables, however for ease of use, this
document combines all three into one easy to understand table.
mg/m3
Asspecified by the equipment user or supplier
100 1 0 - -
100,000 1,000 10 - -
-10,000 500 - -
-- 1,000 - -
- - 20,000 - -
- - - 5 5
- - - 40 10
- - - - -
-----
Solid Particulate
Pressure Dewpoint g/m3
Vapour
As specified by the equipment user or supplier
-70°C-
-40°C -
-20°C-
+3°C -
+7°C -
+10°C-
- 0.5
- 5
-10
Water
Total oil (aerosol, liquid and vapour)
As specified by the equipment user or supplier
0.01
0.1
1
5
-
-
-
-
-
Oil

ISO 8573.1 : 2001 CLASS 0

THE ISO 8573.1 : 2001 TABLE ALSO INCLUDES A CLASS 0 FOR EACH TYPE OF CONTAMINANT. SHOULD AN APPLICATION REQUIRE
COMPRESSED AIR PURITY WHICH IS HIGHER THAN THE LEVELS SHOWN FOR CLASS 1, THEN CLASS 0 ALLOWS THE USER AND AN
EQUIPMENT MANUFACTURER OR SUPPLIER TO AGREE THEIR OWN LEVELS WITHIN THE FOLLOWING GUIDELINES
• THE PURITY LEVELS SELECTED MUST BE MORE STRINGENT THAN THOSE OF CLASS 1
• THE PURITY LEVELS SELECTED ARE MEASURABLE WITH THE TEST EQUIPMENT AND METHODS OF ISO 8573 PARTS 2 TO 9
• THE AGREED LEVELS ARE WRITTEN AS PART OF THE AIR QUALITY SPECIFICATION
IMPORTANT NOTES
• CLASS 0 DOES NOT MEAN ZERO CONTAMINATION ALLOWED IN THE COMPRESSED AIR
• MANUFACTURERS SHOULD NOT STATE PRODUCTS COMPLY WITH CLASS 0 UNLESS PURITY LEVELS HAVE CLEARLY BEEN
DEFINED AND AGREED WITH THE USER
•PURITY LEVELS BEYOND THE ACCURATE MEASUREMENT CAPABILITIES GIVEN IN ISO 8573 PARTS 2 TO 9 SHOULD NOT BE
SELECTED AS THERE IS NO ACCURATE WAY OF VERIFYING PRODUCT PERFORMANCE
•TOOPERATE A COST EFFECTIVE COMPRESSED AIR SYSTEM, CLASS 0 SHOULD ONLY BE SPECIFIED AT THE POINT OF USE
AND FOR THE MOST CRITICAL OF APPLICATIONS

Specifying air purity in accordance with ISO 8573.1 : 2001

When specifying the purity of air required, the standard must always be referenced, followed by the purity class selected for each contaminant
(a different purity class can be selected for each contaminant if required). An example of how to write an air quality specification is shown below :
ISO 8573.1 : 2001 Class 1.2.1
ISO8573.1 : 2001 refers to the standard document and its revision, the three digits refer to the purity classifications selected for solid particulate,
water and total oil.Selecting an air purity class of 1.2.1 would specify the following air quality when operating at the standard’s reference
conditions :
Class 1 Particulate
In each cubic metreof compressed air, no morethan 100 particles in the 0.1 - 0.5 micron size range are allowed
In each cubic metre of compressed air, no more than 1 particle in the 0.5 - 1 micron size range is allowed
In each cubic metreof compressed air, no particles in the 1 - 5 micron size range are allowed
Class 2 Water
Apressure dewpoint of -40°C or better is required and no liquid water is allowed.
Class 1 Oil
In each cubic metreof compressed air, not more than 0.01mg of oil is allowed. This is a combined level for both oil aerosol and oil vapour.
LiquidMaximum number of particles per m3Concentration
Particle Size
0.1 - 0.5 micron 0.5 - 1 micron 1 - 5 micron mg/m3
micron
Purity
Class
0
1
2
3
4
5
6
7
8
9