Met One GT-521 Two Channel Handheld Laser Particle Counter


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The GT-521 is a full-featured, battery-operated, portable laser particle counter that provides the functionality of a bench unit with the convenience of a handheld! It can data-log particle counts continuously or send them to a network.


  • Dual Programmable Channels
    Two programmable particle channels with a range of 0.3 – 5.0 microns each show differential or cumulative particle counts in real time, with selectable count units.
  • Simple and Powerful Menu-Driven Command Set
    A simple touch of a button sets particle sizes, sample time, alarm settings, and basic setup parameters such as date/time and communications settings. Remote operation via RS-232 or RS-485 communications ports allows extensive control, including all front-panel operations.
  • Flexible Data Interfaces
    Stores up to 4,000 records for printer output, Excel® formatted output, or networked datalogging via the included single computer software (GT-Comm).
  • Temperature and Relative Humidity Option
    A plug-and-play option that immediately adds ambient temperature and relative humidity capabilities to the displayed and logged data.



    Particle Size Ranges  Two channels—from 0.3 to 5.0 μm (selectable in 0.1 μm increments)
    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 Adjustable: 6 to 999 seconds
    Light Source Laser diode, 30 mW, 780 nm
    Flow Rate 0.1 cfm (2.83 lpm)
    Display 16-character x 4 Line LCD
    Connectivity RS-232 or RS-485 Half Duplex
    Data Storage Up to 4,000 Records
    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  4.0” (10.2 cm) W x 2.1” (5.4 cm) D
    Weight (with battery) 1.94 lb   (31 oz)   (0.88 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-521 is shipped complete with:

    • Operation Manual
    • Custom Serial Cable
    • Communication Software (GT-Comm)
    • AC to DC Converter Module with IEC AC Power Cord
    • Isokinetic Sample Probe
    • Screwdriver
    • Carrying Case
    • Zero Particulate Filter
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