• At the core of the PMD 331 is the laser Mie-scattering measurement principle, driven by a 50 mW, 780 nm laser light source.
• As air is drawn through the optical chamber, particles scatter the laser light, and the instrument analyses these signals to count and size particles with high accuracy.
• The PMD 331 measures seven particle-size channels at once - 0.3, 0.5, 0.7, 1.0, 2.5, 5.0 and 10.0 micrometres - delivering a comprehensive picture of the particle distribution in a single sample.
• With a measuring range up to 3,000,000 particles per cubic foot and +/-10 percent accuracy, it provides the detail and precision required for demanding cleanliness assessments.

• Practical sampling performance makes the PMD 331 efficient in the field.
• It operates at a 2.83 L/min (0.1 CFM) flow rate with configurable sampling times from 3 to 60 seconds, allowing users to balance speed and statistical confidence for each measurement.
• The instrument can also derive related metrics such as PM2.5, PM10 and TSP-style readings, broadening its usefulness from cleanroom classification to general air-quality investigation.
• A large 4.0-inch TFT LCD presents readings clearly, while substantial on-board memory stores up to 2,000,000 records for thorough data capture and later analysis.

• Connectivity and data management support both field use and documentation.
• The PMD 331 offers USB and RS-232 communication (with RS-485 on newer versions), enabling data transfer to a PC for reporting, trending and archiving.
• This makes it straightforward to generate compliance records, track conditions over time and integrate measurements into quality systems.
• Powered by a rechargeable lithium battery delivering around 8 hours of operation with a 3.5-hour charge time, the instrument supports a full day of mobile measurement, and its handheld form factor (170 x 110 x 48 mm, 850 g) makes it easy to carry between locations.

Built for dependable operation across varied environments, the PMD 331 functions over a 0 to 50 C operating temperature range and tolerates storage from -20 to 60 C, with CE and ISO 21501-4 credentials underscoring its suitability for regulated and professional applications. ISO 21501-4 compliance is particularly important for cleanroom classification and certification, providing confidence that measurements meet recognised international standards for light-scattering particle counters.

For buyers, the PMD 331 offers a professional-grade, standards-compliant particle counter that combines accuracy, comprehensive multi-channel measurement, generous data capacity and practical portability. It is an excellent investment for any organisation that must measure, document and control airborne particle levels with confidence, replacing guesswork with objective, traceable data.