A particle counter detects the presence of matter in a sample source, counts it, and may provide information about its size. Aerosol counters allow technicians to measure particles in air sources or other gases, while liquid counters evaluate liquid samples. Such devices can be useful for quality control, contamination detection, and public health. They are available through scientific supply companies and in some cases it may be possible to receive a grant to fund them, if they are serving a public health function.
Several techniques can be used to check a sample of materials for particles. Two of the most common involve light scattering or obscuration, relying on changes in behavior of light when it passes through a sample with particulate materials. These particle counting devices illuminate the sample, typically with a laser, and measure refracted or obscured light. Other devices can optically scan the sample, which may also provide information about the size of the particles, based on how much area they take up in an image.
One use for a particle counter is in air quality monitoring. High percentages of particulates in the air can be an indicator of pollution or contamination that might make it difficult to breathe. These devices can be used to assess particulate levels and issue advisories if needed. In health care applications, they can be used to monitor for signs of contamination, check for escaped particles, and maintain rigid standards in labs. They are also useful in manufacturing, where delicate processes can be interrupted with airborne impurities.
Some devices are portable; technicians can carry them into an environment and set them up as needed with the appropriate sampling probes. Others are fixed, and may be hardwired into an environment. A remote particle counter can send signals to other devices and control panels. Such equipment is useful for monitoring large areas where technicians cannot personally check the particle counter. The device may send out an alert if levels rise too high to inform technicians they need to respond to an emerging problem.
Documentation associated with a particle counter can provide information about the size range it is capable of detecting. Some devices may also have lower and upper flow limits, beyond which they cannot measure accurately. It is important to select the right equipment to ensure the accuracy and reliability of measurements. The equipment may return errors if it senses that conditions have exceeded its capacity, but in other cases there will be no warning that the measurements are not accurate.