The GT‐521S is a full‐featured, battery‐operated, portable particle counter that provides the functionality of a bench unit with the convenience of a handheld. This powerful device supports cumulative or differential counts, standard concentrations, total counts and count alarms.



Particle Size Range 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 ± 10%, to calibration aerosol
Sensitivity 0.3 μm
Flow Rate 0.1 cfm (2.83 lpm)
Sample Time Adjustable: 6 to 999 seconds
Hold Time Adjustable: 1 to 999 seconds
Light Source Laser diode, 30 mW, 780 nm
Power 6V Ni-MH self-contained battery pack—provides 8 hours of typical intermittent operation, up to 5 hours continuous use
AC Adapter/Charger AC to DC module, 100 – 240 VAC to 9 VDC @ 350 mA typical
Communications RS-232 or RS-485 Half Duplex
Certifications Meets or exceeds CE, ISO, ASTM, and JIS international certifications
Display 16-character × 4–line LCD
Keyboard 7-key membrane type
Size Height = 6.25″ (15.9 cm) Width = 4.0″ (10.2 cm) Thickness = 2.1″ (5.4 cm)
Weight 1.94 lb – 31 oz (0.88 kg)
Operating Temperature 0° to +50°C
Storage Temperature -20° to +60°C
Supplied Operation Manual
Custom Serial Cable
Communication Software (GT-Comm)
AC to DC Converter Module with IEC AC Power Cord
Isokinetic Sample Probe
Carrying Case
Zero Particulate Filter
Optional RH & Temperature Probe (Met One Part Number G3120)
Flow Meter (Met One Part Number 9801)
Portable Printer (Met One Part Number G3115)

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