Compressed air quality
Where compressed air contacts the product, oil or dust in the air can be a costly problem. OIL CHECK 500 and PC 400 continuously measure residual oil vapour and particles and prove the ISO 8573-1 quality class.
Why measure air quality
In the food, pharmaceutical, electronics and semiconductor industries, compressed air often comes into direct contact with the product. Contamination with oil, moisture or particles can have serious consequences – from product recalls to damaged production equipment.
Oil does not only come from the compressor: in industrial areas the intake air already contains so many hydrocarbons that without proper treatment only class 2 or worse is achieved. So even an oil-free compressor does not guarantee oil-free air.
CS Instruments models
Stationary oil monitoring, a laser particle counter and a dew point sensor – together they cover all three ISO 8573-1 classes.
Residual oil measurement
Continuous residual oil vapour measurement from 0.001 mg/m³ for monitoring ISO 8573-1 class 1.
Laser particle counter
Counts particles from 0.1 µm in compressed air and gases to ISO 8573-1, stationary or mobile.
Stationary dew point sensor
Pressure dew point sensor for refrigeration, membrane and adsorption dryers, with Modbus-RTU and IO-Link.
4/8/12-input data logger
Intelligent data logger for all sensors: display, alarms, recording and energy analysis.
Comparison
| Model | Version | Measuring range | Pressure | Outputs |
|---|---|---|---|---|
| OIL CHECK 500 | Stationary | 0.001…5 mg/m³ | 3…9 bar (300 bar) | Modbus-RTU, 4…20 mA, 2 relays |
| PC 400 | Portable | – | 40 bar | Modbus-RTU |
| FA 510 / FA 515 | Stationary | -80…+20 / -20…+50 °Ctd | -1…50 bar (500 bar) | 4…20 mA, Modbus-RTU, IO-Link |
| DS 500 | Stationary | – | – | Ethernet, Modbus RTU/TCP, 4 relays |
Applications
Residual oil and particle measurement is used above all where air contacts the product.
Air for packaging, conveying and blow moulding must not contaminate the product.
A documented quality class for process validation and cleanrooms (ISO 14644-1, EU GMP Annex 1).
Particles and oil vapour on surfaces cause production defects.
Contaminated or wet air causes bubbles and surface defects in painting and coating.
ISO 8573-1:2010
ISO 8573-1 defines limit values for solid particles, water (pressure dew point) and oil. A class is written e.g. as ISO 8573-1 [1:2:1] – particles, water and oil in that order.
Class 1 allows at most 0.01 mg/m³ of oil. OIL CHECK 500 measures residual oil vapour from 0.001 mg/m³ – continuously and stationary.
Air quality →The PC 400 laser particle counter counts particles from 0.1 µm in three size classes, as ISO 8573-1 requires for class 1.
Particle measurement →| Class | Solid particles – number per m³ | Water | Oil (aerosol + vapour) | ||
|---|---|---|---|---|---|
| 0.1–0.5 µm | 0.5–1 µm | 1–5 µm | Pressure dew point | mg/m³ | |
| 0 | As specified by the user – stricter 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 | – | – | – | ≤ +10 °C | – |
Source: CS Instruments catalogue 2025/26 (ISO 8573-1:2010).
How to choose
Define the required class for each consumer, e.g. ISO 8573-1 [1:2:1].
Measure after the last filter or at the critical consumer.
Continuous monitoring with OIL CHECK 500 and PC 400, occasional checks with a mobile case or trolley.
Recording in a DS 500 and reports in CS Network for audits and validations.
FAQ
The three numbers give the class for solid particles, water and oil in that order. [1:2:1] means class 1 for particles, class 2 for water (pressure dew point ≤ -40 °C) and class 1 for oil (≤ 0.01 mg/m³).
Not necessarily. Hydrocarbons also enter the system with the intake air, in industrial areas often so much that class 1 cannot be reached without treatment. Measurement is therefore the only proof.
For particles a laser counter (PC 400), for water a pressure dew point sensor (e.g. FA 510), for oil a residual oil vapour meter (OIL CHECK 500). One DS 500 can record all three.
Yes. OIL CHECK 500, PC 400 and FA 510 are also available as a mobile solution in a service case or on a trolley for checks at several points.
Related measurements
Fill in a short form and we will prepare a proposal for measurement equipment and implementation based on the medium, measuring range, and measurement objective.
