Orion Star™ A221 pH Portable Meter



Range: -2.00 to 20.00

Resolution: 0.1, 0.01, 0.001

Relative Accuracy: +/-0.002

Calibration Points: Up to 5


Range: +/-2000.0 mV

Resolution: 0.1 mV

Relative Accuracy: +/-0.2mV or 0.05%, whichever is greater

EH ORP Mode: Yes


Range: -5 to 105 C

Resolution: 0.1

Relative Accuracy: +/-0.1 C

Offset Calibration: 1 point


Number of Points: 1000 with time and date stamp

Log Function: Manual, Automatic with AUTO-READ

Log Edit: Delete last reading or all


Display: Backlit LCD

Inputs: pH Electrode – BNC, ATC Probe – 8-pin mini-DIN

Outputs: RS-232, USB

Power Adapter: Universal AC, 100-240 VAC

Battery Power: 4 AAs, 800 hrs life

Environmental Requirements: 5 to 45 C and 5 to 85% relative humidity, non-condensing

Regulatory and Safety: CE, TUV 3-1, FCC Class A

IP Rating: IP67, waterproof


The waterproof, battery-operated Thermo Orion Star A221 portable pH meter stands up to the most demanding field applications and delivers over 800 hours of continuous operation. The meter displays pH, mV and temperature readings on a large, backlit LCD screen and automatically locks in stable readings.

Thermo Orion Star A221 portable meter provides a large storage capacity for time-stamped data points, which can be conveniently uploaded to a PC through the meter’s USB and RS-232 ports. Automatic or 1 to 5 point manual calibration makes instrument setup simple, while icons provide quick updates on battery life, electrode status and calibration information. The simple button layout and on-screen messages also assist with calibration and explain setup menu choices.

AUTO-READ function alerts user and locks on-screen readings when stable

  • Up to 5 point pH calibration
  • Automatic recognition of USA/NIST and DIN buffers
  • Easy to recall calibration slope data for procedure checks
  • Non-volatile memory holds up to 1000 data points
  • USB and RS-232 ports to upload data and update included data analysis software
  • Universal power supply or battery power option
  • Includes (4) AA batteries to provide over 800 hours of operation
  • Universal power adapter (sold separately) runs meter on AC power
  • Multilanguage interface supports English, Spanish, French, Italian, German and Chinese
  • IP67-rated waterproof housing (can be immersed up to one hour with no water incursion)
  • 3 year meter warranty

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