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NPM 2 Network Particulate Monitor - Met One Instruments

NPM 3 Network Particulate Monitor

The Met One Instruments, Inc. NPM 3 is a forward light scatter laser nephelometer particulate monitor which automatically measures real-time airborne TSP, PM10, or PM2.5 particulate concentration levels.

The NPM 3 features improved reliability and lower maintenance. Each unit uses a serial cable that allows the device to connect to a laptop, data logger, or CCS+ Comet Cloud Modem. The real-time data is accessible for display, logging, review, and reporting instantly or later time.

The monitor contains a 5-mW diode laser operating at 670 nm wavelength.  A protective optical housing fully encapsulates the laser beam and optics system within the device.

Data from the NPM 3 can be managed using the supplied copy of Met One’s user-friendly, Windows-based, Comet™ communications terminal software.   Comet allows the user to view real-time data and log data to a data file on a computer in .csv format.

The NPM 3 is calibrated using 0.6-micron latex microspheres. These provide an extremely consistent calibration but do not generally match the characteristics of all ambient particulate. A K Factor (multiplier) must be established using a collocated trusted reference source (such as a BAM 1020) for good accuracy and correlation. The default factory K Factor is 1.0.

The K Factor is only valid at the same site and for the same particulate type. If the local particulate source changes, the K Factor may need to be adjusted.

The unit is supplied with a TSP head, Comet software, a mounting bracket, & a hose clamp.


➡️ For further technical information on the NPM 3, please read the published article in Aerosol Science & Technology, Fine particle mass monitoring with low-cost sensors: Corrections and long-term performance evaluation, or click HERE to download the pdf.


  • Plug & Play Operation
  • Seamless Network Integration
  • CCS+ COMET Cloud Plus Compatible | Cloud Data Available on any Smart Device
  • Ideal for Neighborhood Monitoring, Smart City & IoT Applications
  • Field Proven Nephelometer with Filtered Purge Air System
  • Automatic Humidity Control
  • Weatherproof Enclosure
  • Compact, Low Power
  • 24-Month Service Interval
  • Excellent Accuracy & Long-Term Stability
  • Adjustable “K” Factor
  • Low Cost


Specifications are subject to change at any time.
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