Contamination by particles can produce deleterious effects in a number of ways; consequently, the analysis of the particulate content of air, gases and liquids represents an important way that this hazard can be monitored. Particular matter in the air is associated with health effects in humans and other dangers to the environment. Particles in manufacturing facilities or process streams can indicate unwanted contaminants, or signs of wear and degradation. A wide variety of particle counter systems provide information about these hazards in many different application areas. While many systems for particle characterization also analyze the size distribution of particles in a sample, the focus of this profile is on instruments that primarily provide a total count or concentration of particles.

Particles in a transparent medium, whether air or water, can block light when they pass in front of a sensor, so that light obscuration is a common method of particle counting. Other light-based instruments make use of the scattering of light off of small particles, or direct imaging of the particles. For detecting very small particles in air, condensation counters cause the particles to act as nuclei for the condensation of droplets—these larger droplets can then be detected by other methods. Another class of instruments use the Coulter principle. If the sample flows through an aperture outfitted with electrodes, the passage of particles through the aperture causes changes in resistance between the electrodes, resulting in a signal that can be processed.

Airborne particles in the atmosphere are monitored both in the external environment and indoors, and help form a determination of air quality. Specific manufacturing environments may require very low levels of particular matter in the air. Under these cleanroom conditions, air must be monitored in order to ensure proper air quality is maintained. Different levels of stringency exist for different categorizations of cleanroom, setting limits on the maximum concentration of particles that may be present.

Drinking water is a common application that is monitored for particle contamination, and many manufacturing activities in pharmaceutical or food production lines can also be monitored. Semiconductor wafer manufacturing is another important application, as large particles that may form during chemical mechanical polishing can damage the product. Other industrial uses involve hydraulic and lubrication fluids, which must be monitored for particles that may hamper performance or damage the overall system. Cells can also be counted in this fashion, and there are specialized systems to count cells for clinical and research purposes.

Several Danaher firms are involved in particle counting, making it the leading vendor. Beckman Coulter offers systems for many different applications. Hach and Fluke offer portable systems for air quality testing. The total market for particle counters was about $160 million in 2015.

Particle Counters at a Glance:

Leading Suppliers

• Danaher

• Rion

• Lighthouse Worldwide

Largest Markets

• Pharmaceuticals

• Semiconductors & Electronics

• Environmental

Instrument Cost

• $2,000–$30,000