Particle counters

A particle counter is a very useful tool for checking indoor air quality (IAQ) for example in clean rooms and workplaces, since a particle counter measures the concentration of particles in the air. While a particle counter does not specifically identify what type of dust or particles are present in the air, a particle counter will tell us how many particles are in the air of a certain size that are present in the environment. One conclusion is based on the materials known in the area and the corresponding sizes of the air particles of those materials.

Exposure to exhaust fumes, smoke, harmful air pollutants and airborne particles are a health hazard and can lead to sneezing, congestion and runny nose, itching or redness, headaches, fatigue, fever, cough, lack of oxygen, dermatitis, asthma, bronchitis, pneumonia and cancer. In addition, several materials are explosives in the form of dust. Combustible dust is a very serious risk to the safety of workers in industry such as agriculture, chemical manufacturing, pharmaceuticals, furniture and textile manufacturing, fossil fuel power generation, recycling, metalworking, additive manufacturing and 3D printing, among others. A particle counter can be used to monitor particle levels to ensure good cleaning practices in the manufacturing area.

Pollution is mainly generated by combustion, material processes, manufacturing, energy production, vehicle emissions and in the construction industry.

The particles in the areas are of different size and shape, such as skin scales, hairs, spores, pollen or grains of earth or metal pieces. In general, instruments measure the scattering of light and report the particle size as if the scattering had been created by a fully spherical particle, therefore the measurement does not correspond exactly to the dimensions of the particle, but to the dimensions of the spherical particle that would diffract the same amount of light.

In the semiconductor industry it is sought to remove particles of a few nanometers (10-9m), but in most applications of the pharmaceutical or medicinal industry the size to be measured ranges from 0.5μm to 10μm (10-6m).

The instruments report the number of particles in different channels, which are size ranges defined by standard or by the user.

The particles are counted through light scattering. A high-power light source is used to illuminate the particles as they pass through the meter's detection chamber (usually a laser). The camera has mirrored walls that reflect scattered light back to the detector.

The particles pass through the chamber with the help of a vacuum pump that forces air through the detection chamber.

When the scattering method is used, a laser illuminates the particles when they pass the detection chamber and the light scattered by the particles is concentrated by an optical system and measured by a luminous detector.