pH Portable Meter

pH Portable Meter

  • pH Range: -2.000 to +20.000, RH Range: 5 to 85%, non-condensing
  • ORP, mV and Relative mV Range: ±2000.0mV
  • Temperature Range: 22.0° to 221.0° F, -5.0° to 105.0° C

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Record accurate and reliable pH, mV, ORP and temperature measurements with the Thermo Scientific Orion Star A221 pH Portable Meter

Ideal for a wide range of applications and advanced pH analysis in the field. Perform up to a five point pH calibration, log up to 1000 data point sets with time / date stamp and easily transfer calibration and data logs via USB or RS232 to a printer or computer with free downloadable Orion Star Com software. Waterproof meter ensures durable, rugged performance in outdoor environments with an IP67-rated housing.

Don’t leave your measurements to chance when analyzing samples outside the lab. Orion Star A221 pH portable meters are designed to offer the reliability you need in a user-friendly package for your dedicated pH testing needs. This waterproof portable meter displays critical data with your measurement including temperature, date and time, read type, measurement stability, active calibration info and power source status.

  • Measure pH, mV, relative mV or ORP with temperature
  • Perform up to a five point pH calibration using automatic buffer recognition of NIST or DIN buffer groups with choice to manually enter custom buffer values
  • Informative, easy-to-read backlit graphic display with clear onscreen instructions simplifies operation
  • Capture your critical readings with measurement stability indicator and selectable read modes – Auto-Read holds a stable reading and Continuous shows changing readings with hold option
  • Data log collects and date/time stamps up to 1000 measurement sets
  • Non-volatile meter memory ensures your data and settings are protected, even with loss of power
  • Orion Star Com software facilitates data transfer to a computer via USB or RS232 connections
  • Flexible power options with AA batteries or optional universal power adapter
  • IP67-rated housing is waterproof for rugged field operation
  • Meter kits include hard-sided field case and protective meter armor with electrode holders, adjustable wrist/belt strap and built-in meter stand
  • Meters offer CE, TUV 3-in-1 and FCC Class A certifications and 3-year replacement warranty


Many configurations, electrodes, consumables and accessories available on request.

Operating Temperature41° to 113°F (ambient)
5° to 45°C (ambient)
StabilitySmart Stability and Smart Averaging
Resolution (Temperature)0.1°C, 0.1°F
Temperature Range22.0° to 221.0° F
-5.0° to 105.0° C
Temperature Probe Calibration1 point temperature offset calibration
Warranty3 year meter warranty
Weight1.2 lb.
0.5kg
Temperature SelectionManual or automatic with ATC temperature probe
AC AdapterUniversal 50-60 Hz, 100-240 VAC power adapter (sold separately, Cat. No. 1010003)
Accuracy (pH)±0.002pH
Accuracy (mV)±0.2 mV or ±0.05% of reading whichever is greater
Backlight OptionYes, selectable
Alarm OutputCalibration due alarm (fixed 12 hour)
Accuracy (Temperature)±0.1°C
Battery Life800 hr.
Battery Type4 x AA
CalibrationpH, relative mV (RmV),ORP and temperature
Calibration Points1 point relative mV (RmV) mode, 1 point ORP mode
Data Management DetailsTransfer single, range or all data points to printer or computer
Channels1
Certifications/ComplianceCE, TUV 3-1, FCC Class A
LanguagesEnglish, Spanish, French, Italian, German and Chinese; Portuguese and Korean available with software update
Log Function TypeAutomatic data logging with Auto-Read measure mode; manual data logging with Continuous measure mode
Dimensions (L x W x H)24cm x 10cm x 6.5cm (9.5 in. x 3.9 in. x 2.6 in.)
Data Points1000 with date and time stamp
Display TypeLCD (Graphic with backlight)
Resolution (pH)0.1, 0.01, 0.001
Range (pH)-2.000 to +20.000
IP RatingIP-67
InputsBNC (pH or ORP electrode),pin-tip (reference electrode),8 pin MiniDIN (ATC temperature probe)
Isopotential Point7.000pH
KeypadComprehensive with menu-specific function keys and dual purpose scroll/shortcut keys
MemoryNon-volatile memory preserves data log, calibration log and meter settings
Methods10 per channel with password protection
Measurement ModespH, mV, relative mV (RmV) or ORP with temperature
OutputsUSB, RS-232
Probe TypepH electrode, ORP electrode, reference half-cell electrode, ATC temperature probe (purchase separately)
Power SupplyUniversal AC adapter (included) or 4 AA batteries (sold separately)
Range (ORP)±2000.0mV
Range (Relative mV)±2000.0mV
Relative Humidity Range5 to 85%, non-condensing
Resolution (mV)0.1mV
Range (mV)±2000.0mV