This measurement determines the number and size of the particles present in the compressed gas. The presence of particles, even microscopic ones, can lead to product defects, particularly in advanced industries such as electronics or pharmaceuticals.

The presence of oil in compressed gas may result from compressor maintenance issues. Oil can be deposited on products and alter their properties.

The dew point is the temperature at which the water vapour contained in the compressed gas begins to condense. Excessive humidity can promote the development of corrosion and micro-organisms.

Compressed gas may be contaminated by bacteria, moulds or yeasts. These micro-organisms can proliferate and contaminate products, particularly in the food and pharmaceutical industries.

Compressed gas may contain gaseous impurities such as hydrocarbons, carbon monoxide or nitrogen oxides. These contaminants can have adverse effects on products or on the environment.