Compressed air quality testing equipment

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How to test compressed air quality?

Fortunately, measuring air quality has become much easier than in the past with a range of tools available.

Let’s look at the technologies you can use by contaminant.

How to measure moisture in your compressed air?

Measuring moisture was a real challenge for a long time and, if you are using a very old compressed air dryer, there is a good chance that it does not feature an accurate moisture content sensor.

Moisture indicator

A very inexpensive option to use is a moisture indicator, which can be installed anywhere in your system downstream from an air dryer (up to the point of use). A color change from blue to pink indicates that the moisture level is on the rise. It is important to note that this is only an indication and not an accurate measurement.

Chilled mirror technology

On the other end of the spectrum in terms of cost is the chilled mirror technology, which is also the most accurate but also very sensitive. Here, a chilled mirror and an optoelectronic mechanism are used for detecting condensation on the mirror’s surface.

These devices are not only expensive but also require frequent cleaning, a trained operator, and periodic calibration to maintain their high level of accuracy. As a result, they are not used for continuous moisture measurement and have also become an increasingly less popular option for audit purposes.

Capacitive type dew point sensors

Then there are capacitive type dew point sensors, which are suitable for continuously monitoring the dew point of your compressed air. By providing feedback to the dryer, they can offer you energy savings in combination with the appropriate dryer controls. This equipment is not just available for desiccant but also for refrigerant dryers, which makes it the preferred technology for audit purposes and for continuous monitoring.

How to measure oil in your compressed air?

There are various technologies that allow you to measure the oil content in your compressed to ensure that you are in compliance with the applicable air quality standards.

Sampling solutions

An Atlas Copco O-box is a low-cost sampling solution indicating a high oil concentration in the air when the oil is present in liquid or aerosol form, which means it is a solution for applications where the air does not have to be very pure (up to class 2).

Glass test tubes

Glass test tubes are another cost-effective way of checking for oil periodically. Typically used behind a QDT, it is able to measure low oil vapor concentrations down to ISO 8573-1 Class 1. As a result, you will know if you are complying with all but the most stringent air quality standards.

Photoionization detectors (PID sensors)

Then there are photoionization detectors (PID sensors), which constitute a cost-effective method for determining the oil vapor content in your compressed air. They also allow continuous monitoring with data storage. However, some brands will recognize moisture as oil and therefore offer a false result, so make sure that you get a quality PID.

Gas chromatography

The final technology you can employ is gas chromatography, a process often used in analytical chemistry to test the purity of a particular substance, such as compressed air in this case. This is the only method that can be used to ensure that you are in compliance with even the most stringent air quality requirements.

How to measure particles in your compressed air?

Laser technology

Particles are counted optically, e.g. with a laser. This laser monitors a sampling of the air. However, it is very important to get the sample right, especially when a very high air quality has to be achieved (ISO 8573-1 class 1).

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