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GT-521S Handheld Particle Counter

Product SKU: GT-521S

Quick Overview

Battery-operated, portable the GT-521S is a fully featured particle counter. With all the power and function of a bench unit, yet conveniently in a handheld size, the GT-521S supports differential and cumulative counts, total counts, count alarms, and standard concentrations. Additionally, it can datalog particle counts either continuously or send them to a network.

Availability: In stock




The aluminum enclosure provides protection from bumps and scrapes that can damage plastic instruments. A rugged carrying case is also provided.


The GT-521S allows the user to select particle sizes with two programmable count channels with 0.3 to 10 microns each show differential or cumulative particle counts in real time, with selectable count units.

The GT-521S a 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. The GT-521S can store up to 8,000 sample events. Sample history can be viewed on the local display or download to a computer using Comet software. With flexible data interfaces the GT-521S can stores up to 4,000 records for printer output, Excel® formatted output, or networked datalogging via the included single computer software (GT-Comm).

The GT-521S is battery powered with 24 hours of typical (intermittent) operation or 10 hours of continuous operation from a single charge. Recharge time is approximately 2.5 hours. The GT-521S can also come with a temperature / relative humidity plug-and-play option, which immediately adds ambient temperature and relative humidity capabilities to the displayed and logged data.


  • 2 channels of monitoring user selectable
  • Simple & powerful menu driven functionality
  • Adjustable sample time
  • Differential or cumulative
  • Battery or AC Powered


  • Controlled Environments
  • Indoor Air Quality
  • Process Control
  • HVAC Applications
  • Filter Testing
  • Compliance Testing
  • Emission Sourcing
  • Remote Sampling

Additional Information

Particle Size Range: Two channels—from 0.3 to 5.0 μm (selectable in 0.1 μm increments)
Calibrated Sizes: 0.3 μm, 0.5μm, 1.0μm, 2.0μm 5.0μm and 10μm
User Size Settings: 0.1μm steps from 0.3μm – 2.0μm
0.5μm steps from 2.0μm – 10μm
Concentration Range: 0–3,000,000 particles per cubic foot (105,900 particle/L)
Accuracy: ±10% to calibration aerosol
Sensitivity: 0.3 μm
Flow Rate: 0.1 cfm (2.83 lpm)
Data Storage: 8,000 samples
Sample Time: Adjustable: 6 to 999 seconds
Hold Time: Adjustable: 1 to 999 seconds
Light Source: Laser Diode, 90mW, 780 nm
Power: 6V Ni-MH self-contained battery pack—provides 8 hours of typical intermittent operation, up to 5 hours continuous use
Battery: 7.4V 2,200 mAH Li-ion battery pack.
Battery Operation: 10 hours continuous operation. Battery recharge time is 2.5 hours.
AC Adapter/Charger: Li-ion battery charger, 100 – 240 VAC, 50/60Hz
Communications: USB,RS-232orRS-485
Certifications: Meets or exceeds CE, ISO 21501-4
Display / Keyboard: 16 character x 4 line LCD / 7 key membrane type
Data Memory: 8,000 records
Computer Interface: RS232 / RS485 / USB
Power Supply / Charger: Yes
Cont. Operating Time: 6 hours
Recharge Time: 2.5 hours
Software: Yes
Size: Height = 6.25″ (15.9 cm)
Width = 4.0″ (10.2 cm)
Thickness = 2.1″ (5.4 cm)
Weight: 2.00 lbs (0.91 kg)
Operating Temperature: 0 ̊ C to +50 ̊ C
Storage Temperature: -20 ̊ C to +60 ̊ C
Supplied: Operation Manual (PN GT-521S-9800)
USB Cable (PN 500787)
Custom Serial Cable (PN 500787)
Comet Software (PN 80248)
AC Adapter / Battery Charger (PN 390031)
Iso-kinetic Sample Probe (PN G3110)
Carrying Case (PN 8517)
Screwdriver (PN 8517)
Zero Particulate Filter (PN G3111)