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| OPERATING PRINCIPLE | Counts individual particles using scattered laser light |
| PERFORMANCE | |
| 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) |
| ELECTRICAL | |
| 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 |
| INTERFACE | |
| Display | 16-character LCD |
| Keyboard | 2-button membrane |
| PHYSICAL | |
| 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) |
| ENVIRONMENTAL | |
| Operating Temperature | 0° to +50°C |
| Storage Temperature | -20° to +60°C |
| ACCESSORIES | |
| Supplied | Operation Manual Custom Serial Cable AC to DC Converter Module with IEC AC Power Cord Isokinetic Sample Probe Screwdriver Carrying Case Zero Particulate Filter |
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.

