Particle counters, frequently called dust monitors, are instruments designed to quantify the amount of microscopic particles in an air sample. These instruments are capable of detecting, sorting and measuring the concentration of particles as small as fractions of micrometers.

Airborne particulates come from many sources. Some of these particulates are naturally occurring and originate from sea salt, mineral dust, wildfires, vegetation and other sources. Other particulates are generated by human activities such as burning fossil fuels, mining, and various industrial processes.

Regardless of the origin of the particulates, there is a need to identify high concentrations of them and to develop mitigation strategies where needed. Particulates not only interfere with certain industrial processes, they are also a major source of air pollution responsible for severe health consequences. Both the International Agency for Research on Cancer and the World Health Organization have identified airborne particulates as Group 1 carcinogens made particularly lethal by their ability to penetrate deep into the lungs.

Applications for Particle Counters

Given the effect of airborne particles on both health and industrial/commercial operations, particle counters are indispensable tools for a wide range of applications that are concerned with air quality and hygiene, especially those that must comply with certification or regulatory standards. Some common applications involving particle counters include:

  • Clean room classification
  • Indoor air quality surveys
  • Traffic-related emission monitoring
  • Occupational health control
  • Diesel vehicle transportation & service depots
  • Power generation (fossil fuel burning)
  • Cement manufacturing, mining, & stone crushing
  • Metallurgy processes (melting, pouring, torch-cutting)
  • Agro-industrial (flour milling & agricultural field burning
  • Checking the effectiveness of filters

How Particle Counters Work

Airborne particles exist in an extraordinary range of sizes, shapes and compositions. The technology required to count those particles and identify them by size is impressive.

Though different measuring technologies are available in modern particle counters, by far the most common type are based upon light scattering.

In light scattering particle counters, a very bright light source, generally a laser, shines through an optical block that contains mirrors and photo detectors. A small pump draws the sampled air through the optical block and into the path of the laser beam where entrained particles cause the light to bounce, or scatter, off of individual particles.

As the light scatters, it is picked up by the mirrors and focused onto the photo detectors where the flash of light energy from each particle is converted into a pulse of electrical energy. By counting the number of pulses, we can determine the number of particles. If we measure the height of each pulse and compare it to a calibration curve, we can determine the size of the particles.

Since individual particles can vary considerably from one another, effects such as absorption or phosphorescence may occur from some particles types. Even the way an individual particle is oriented can affect how it’s detected. The calibration curve helps maintain accuracy in these instances of random variances.

Things to Consider When Selecting a Particle Counter:

  1. What is the application?
  2. Does the particle counter meet regulatory standards for the application?
  3. What are the particle size you are concerned with detecting?
  4. What flow rate is suitable for your application?
  5. Is the detector intended for laboratory or field work?
  6. Do you need multi-channel capabilities?
  7. Are any calculations (cumulative, differential, concentration) desired?
  8. What accessories (such as probes) are necessary?
  9. Do you need communications or data logging functions?

If you have any questions regarding particle counters, please don't hesitate to speak with one of our engineers by e-mailing us at sales@instrumart.com or calling 1-800-884-4967.