Air Quality | GT-321 Single Channel Particle Counter

GT-321 Single Channel Particle Counter

The reliability you demand at a price you won’t believe!

Small Size—Big Performance
The handheld GT-321 is a portable particle counter that counts particles down to 0.3 microns—giving you portability and reliability at the lowest price in the industry.

Completely Self-Contained—Selectable Particle Sizes
Don’t let the size fool you—the GT-321 is completely self-contained 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.

Off-the-Shelf Delivery
Units are available for same-day or next-day shipping!

Single Channel
Particle Counter

PDF icon Data Sheets
PDF icon Manual


OPERATING PRINCIPLE Counts individual particles using scattered laser light
Particle Size Range >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 ± 10%, to calibration aerosol
Sensitivity 0.3 μm
Flow Rate 0.1 cfm (2.83 lpm)
Sample Time 1 minute total (first reading in 9 seconds, subsequently every 6 seconds)
Light Source Laser diode
Power 6V 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
Certifications Meets or exceeds CE, ISO, ASTM, and JIS international certifications
Display 16-character LCD
Keyboard 2-button membrane
Size Height = 6.25" (15.9 cm) Width = 3.65" (9.3 cm) Thickness = 2.0" (5.1 cm)
Weight 1.74 lb – 28 oz (0.79 kg)
Operating Temperature 0° to +50°C
Storage Temperature -20° to +60°C
Supplied Operation Manual
Custom Serial Cable
AC to DC Converter Module with IEC AC Power Cord
Isokinetic Sample Probe
Carrying Case
Zero Particulate Filter

Whatever your particular needs, the right choice is only natural.

  • Controlled Environments
  • Indoor Air Quality
  • Process Control
  • HVAC Applications
  • Filter Testing
  • Laboratory Environments
  • Manufacturing Environments
  • Emission Sourcing