Classification of Compressed Air Quality

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This guide has been prepared to show you the classifications of compressed air quality. This can help when trying to find the most suitable air compressor for your production.

As your partners in compressed air we will continue to provide you with the resources to ensure that you have the most efficient and reliable compressed air system for your production. 

ISO standard 8573.1 for the classification of compressed air quality

Quality class Solid particle content Water content Oil content
Max. size mu
Max. amount mg/m³  Dew point °C  Amount g/m³
Max. amount mg/m³ 
1
0.1
0.1 - 70 0.003  0.01
2  1 1 - 40 0.11 0.1
3 5 5 - 20 0.88 1.0
4  40 10 + 3 6.0 5
5 - - + 7 7.8 25
6  - - + 10 9.4 -

Typical requirements for compressed air quality classes according to ISO 8573.1 for some users

Application areas Quality Class
Solid particle content Water content Oil content
Air stirring 3 6 3
Air motors, large  4 5-2 5
Air motors, minature  3 4-2 3
Air turbines  2 3 3
Transportation of granulates  3 5 3
Transportation of powder  2 4 2
Fluidistors  2 3-2 2
Foundry machinery  4 5 5
Contact with provisions  2 4 1
Pneumatic tools, industrial  4 6-5 4
Mining Machinery  4 6 5
Packaging machines  4 4 3
Textile machinery  4 4 3
Pneumatic cylinders
3 4 5
Film Handling  1 2 1
Precision Regulators  3 3 3
Process Instruments
2 3 3
Sand blasting  - 4 3
Spray painting  3 4-3 3
Welding machines  4 5 5
  5 4 5

The air's water content at different dew points

Dew Point °C g/m³ Dew Point °C g/m³ Dew Point °C g/m³ Dew Point °C g/m³
+ 100
588.208 58  118.119 16  13.531 -26  0.51
98  550.375 56  108.2 14  11.987 -28  0.41
96
514.401 54  98.883 12  10.611 -30  0.33
94  480.394 52  90.247 10  9.356 -32  0.271
92  448.308 50  82.257 8  8.243 -34  0.219
90  417.935 48  74.871 6  7.246 -36  0.178
88  389.225 46  68.056 4  6.356 -38  0.144
86  362.124 44  61.772 2  5.571 -40  0.117
84  336.661 42  44.989 ±0  4.868 -42  0.093
82  311.616 40  50.672 -2  4.135 -44  0.075
80  290.017 38  45.593 -4
3.513 -46
0.061
78  268.806 36  41.322 -8  2.984 -48  0.048
76  248.841 34
37.229 -12  2.156 -52  0.031
72  212.648 30  30.078 -14  1.81 -54
0.024
70  196.213 28  26.97 -16  1.51 -56  0.019
68
180.855 26
24.143 -18
1.27 -58  0.015
66 166.507 24
21.587 -19  1.05 -60  0.011
64  153.103 22
19.252 -20  0.88 -70 0.0033
62
140.659 20  17.148 -22
0.73 -80
0.0006
60
129.02 18  15.246 -24
0.61 -90  0.0001
Classification of Compressed Air Image

Continue through our compressed air guide:
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Compressed Air Budget - Part One >