Met One GT-321 Single Channel Handheld Laser Particle Counter


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The handheld GT-321 is a single channel handheld laser particle counter that counts particles down to 0.3 microns—giving you portability and reliability.


  • Self Contained with Selectable Particle Sizes
    Don’t let the size fool you—the GT-321 is completely selfcontained with its own internal battery and sample pump, and is programmable, allowing you to choose your particle size of interest from five sizes: 0.3, 0.5, 1.0, 2.0, or 5.0 microns
  • Fast Sampling
    Unlike other counters that can take up to a minute to deliver results, the GT-321 starts delivering volumetric concentration results in about 6 seconds! This facilitates quick multi-site sampling, tracing particle sources and site particle trending.
  • Simple Operation
    Only two front-panel buttons control the size channels and sample cycle. The side-mounted power switch allows for convenient thumb operation.
  • Battery or AC Powered
    The self-contained battery pack powers the unit for 8 hours of typical intermittent operation, and for up to 5 hours of continuous use. The included AC adapter operates the counter, even when the battery pack is discharged, and recharges the depleted battery overnight (16 hours) when turned off.



    Particle Size Ranges  >0.3, >0.5, >1.0, >2.0, and >5.0 µm  (selectable)
    Concentration Range 0 – 3,000,000 particles per cubic foot (105,900 particles/L)
    Accuracy Accuracy  ± 10%, to calibration aerosol
    Sensitivity 0.3 μm
    Sample Time 1 minute total (first reading in 9 seconds, subsequently every 6 seconds
    Light Source Laser diode, 30 mW, 780 nm
    Flow Rate 0.1 cfm (2.83 lpm)
    Display 16-character LCD
    Connectivity RS-232
    Data Storage None. Supports real time data output via RS-232 connection
    Operating Temperature 0˚ to +50˚C
    Storage Temperature -20˚ to +60˚C
    AC Adapter/Charger AC to DC module, 100–240 VAC to 9 VDC @ 350 mA typical
    Battery Life Up to 5 hours of continuous use; up to 8 Hours intermittent Use
    Battery Type 6v NiMH
    Battery Recharge Time 2.5 Hours Typical
    Physical Dimensions 6.25” (15.9 cm) H x  3.65” (9.3 cm) W x 2.0” (5.1 cm) D
    Weight (with battery) 1.74 lb   (28 oz)   (0.79 kg)
    Certifications Meets or exceeds CE, ISO, ASTM, and JIS international certifications
    Warranty Warranted by Met One Instruments for 1 year against defects in workmanship.

    Each Met One GT-321 is shipped complete with:

    • Operation Manual
    • Custom Serial Cable
    • AC to DC Converter Module with IEC AC Power Cord
    • Isokinetic Sample Probe
    • Screwdriver
    • Carrying Case
    • Zero Particulate Filter
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