A particle counter is an instrument that counts and sizes individual particle as they pass through the sensing zone in a flowmeter for liquids. Particle counters can be categorized as light scatter particle counters, light obscuration or extinction particle counters and electrozone particle counters. An electrical signal is generated for each particle as it moves through flowmeters for particle counters that individually counts and sizes particles. The flow of the sample is fundamental to the operation of particle counters which enumerates individual particles. No signals will be generated of there is no sample flowing thus, no particles pass through the sensing zone. The particle concentrations in a liquid sample are expressed as a number of particles greater than or equal to a specified size per milliliter of sample.
As the liquid or fluid flows through the detection chamber a high intensity light source is used to illuminate the particles. The redirected light is detected by a photo detector as the particle passes through the light source. A computer software will analyse the recorded video to measure particle attributes. The use of a high resolution camera and a light to detect particles are needed for direct imaging particle counting. Two dimensional images are analysed by computer software to obtain particle size measurement in the laboratory. Particle size, colour and shape analysis could also be determined by the software.
If air quality is being determined, aerosol particle counters are used by counting and sizing the number of particles in the air. It is also used in determining the cleanliness level of a controlled environment just like a clean room for semiconductor factories, biotechnology, pharmaceuticals, and aerospace and other industries that require and are sensitive to environmental contamination. Clean rooms have standards on the amount of particles in the environment.
To determine the quality of liquid, i.e. water quality, passing through a flow meter, liquid particle counters are used. It can determine if the liquid is clean enough to be used for the desired application. It is used to test the quality of drinking water/tap water for households or cleaning solutions, or the cleanliness of power generation equipment, manufacturing parts and injectable drugs. 75 to 80 percent of hydraulic breakdowns can be attributed to contamination. So, liquid particle counters are also used to determine the cleanliness level of hydraulic fluids that are used in heavy equipment like pumps and cranes. A proactive or predictive maintenance program can be planned which reduces hydraulic failures and increases uptime and machine availability and reduces oil consumption when the cleanliness of hydraulic fluids are monitored.
Measurement of dry particles for various industrial applications are required by standardizing organizations globally, thus, solid particle counters are also available. For example, solid particle counters are needed for detection of particle size coming from a rock crusher in a mining quarry. Different sieve sizes are the basic or standard instruments used to measure dry particle size. Some industrial applications can only require vision based systems to measure dry particle size. With machine vision based technology or system, a quick and efficient particle sizing method can be done with ease and tremendous accuracy.