Provide Essential Air Quality Measurements With These Particle Counters

Particle counters are often overlooked in a firm’s lineup of test equipment. But they can prove to be valuable in many industries for achieving the highest-quality products. These measurement tools can detect and measure microscopic particles suspended in air that can contaminate the most carefully planned manufacturing lines. Often referred to as “clean room checkers,” they draw in air at a controlled rate and rely on several types of sensors to measure airborne particulate matter. The particle counters are tuned and calibrated for detecting particles within a certain size range and a specific air flow rate. With enough onboard memory, they can determine the ratio of particles to a large volume of air.

Particle counters can also be designed for measuring microscopic particles in liquids and chemicals, but units capable of counting airborne particles are often called upon to evaluate levels of environmental cleanliness for a wide range of industries, including manufacturers of aerospace and defense (A&D) equipment, electronics/semiconductor devices, and medical/pharmaceutical products. Particle counters provide a way for a facility to measure that its indoor air quality is within the limits of government and industrial standards required to prevent contamination and ensure high product quality and safety.

Air particle counters can be designed for various applications, including large units for continuous, local or remote automatic monitoring of a facility’s air quality and as smaller, portable units for on-site air quality measurements. Whether large or small, they are typically equipped with an air pump which creates a vacuum within the particle counter that is used to create an air flow into the unit at specified rate. Air particle counters can be built to meet regulatory requirements and calibrated with a calibration certificate according to numerous organizations, such as the National Institute of Standards and Technology, the European Union, and the International Organization for Standardization. Applicable international standards for particle counting are EU GMP Annex 1 and ISO 14644, with ISO 14644-1:2015 defining ultrafine particles as those smaller than 0.1 µm and macroparticles as being larger than 5 µm.

When specifying an air particle counter, numerous capabilities can help differentiate units from different manufacturers, such as the particle size measurement range, the number of measurement channels, the flow rate, the power source (such as AC or rechargeable battery), and the digital interface. Some air particle counters provide additional measurement capabilities, such as for humidity and temperature. Particle measurement sizes can be quite small, since a grain of salt is typically about 60 µm long while a COVID-19 virus ranges about 0.06 to 0.14 µm in length. Laser-driven optical measurement methods employing laser diodes and photodetectors are often used for air particle counting because of their high resolution and sensitivity.

Counting Testers

Portability provides flexibility for air particle counting tasks, and the TSI, Inc AeroTrak™ 9306-V2 features an integrated handle and 3.6-in. color touch screen for ease of one-handed operation. The compact tester is powered by a removable, rechargeable lithium-ion (Li-ion) battery. Available for rent from Transcat, it can measure particles from 0.3 to 25.0 µm in size using as many as six simultaneous measurement channels at flow rates to 2.83 L/minute or 0.1 cubic feet per minute (0.1 CFM). The particle counter has Ethernet and USB interfaces and is compatible with TSI’s TrakPro™ Lite Secure and FMS 5 software. It can perform pass/fail air quality testing according to well-established standards, including ISO 14644-1, EU GMP, and FS209E. The particle counter, which complies with all the requirements of ISO 21501-4, provides enough data storage for 10,000 samples. Measurements are performed by means of a long-life laser diode and the model 9302-V2 is available with sensors for measurement of air temperature and relative humidity (RH) as options.

Also compact and portable, the Lighthouse ApexZ50 cleanroom particle counter is powered by hot swappable “smart” rechargeable batteries. Measuring just 12.26 × 6.23 in. (32.41 × 15.32 cm), it can detect particles in size from 0.5 to 25.0 µm at flow rates to 100 L/minute. It employs advanced self-diagnostic capabilities to help maintain high accuracy and reliability and can move test data by means of several available data interfaces, including Wi-Fi, USB, and Ethernet ports.

Compact and light at 5.6 kg without its Li-ion rechargeable battery, the Beckman Coulter MET ONE 3445+ GMP Cleanroom Air Particle Counter measures particles from 0.5 to 10.0 µm at flow rates to 100 L/minute. Providing accurate measurements by means of a laser diode and photodetector, it achieves counting efficiency of 50% for 0.5-µm particles and 100% efficiency for particles 0.75 µm and larger.

This portable unit allows operators to define their air quality assessments by means of programmable sampling maps and standard operating procedure (SOP) monitoring maps which can be loaded into the particle counter via an Internet web browser. It includes a bright liquid-crystal-display (LCD) screen to ease measurements and monitoring with the screen showing, for example, completed measurements and samples. Remote monitoring is simplified by user Internet access to the particle counter via Ethernet, USB, and IEEE 802.11b/g wireless interfaces. The unit contains enough embedded memory for as many as 1 million samples. It typically operates for 5.7 hours on its rechargeable Li-ion battery.

The Fluke 985 particle counter has a particle size measurement range of 0.3 to 10.0 µm using six channels handling maximum sizes of 0.3, 0.5, 1.0, 2.0, 5.0, and 10.0 µm. The model 985 runs at flow rates to 2.83 L/minute, showing results on a vivid 3.5-in. QVGC color display with backlight. Counting efficiency is 50% for particles of 0.30 µm and smaller and 100% for particles 0.45 µm and larger. With enough on-board memory to store 10,000 records, this versatile tester weighs just 1.5 lb. (0.68 kg) and measuring 10.7 × 3.9 × 2.1 in. (27.2 × 9.9 × 5.3 cm). With its straightforward layout, it is well suited for single-hand operation. It provides 10 hours typical operating time from rechargeable Li-ion batteries and allows operators to set an alarm for a given sample size count. This particle counter generates Excel-compatible data files and does not require special dedicated software for use. It incorporates Ethernet and USB interfaces for ease of data transfers.

Air particle counters may not have the universal appeal of a digital voltmeter or spectrum analyzer, but for cleanrooms and other manufacturing facilities they provide essential measurement capabilities that can help avoid contamination and support high manufacturing yields. More information on any of these particle counters can be found on our website or by contacting a Transcat | Axiom Rental Account Manager for guidance at (760) 806-6600.