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Thermo Scientific™ Orion Star™ A221 Portable pH Meter

Reliably measure pH, mV, ORP and temperature with our portable pH meter for advanced field analysis and printer or computer interfacing.

Manufacturer:  Thermo Scientific™ STARA2215

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Catalog No. 13-645-524



Record accurate and reliable pH, mV, ORP and temperature measurements with the Thermo Scientific™ Orion Star™ A221 Portable pH Meter. This meter is ideal for a wide range of applications and advanced pH analysis in the field. Perform up to a 5 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 Portable pH 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 5 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
  • 3-year replacement warranty


Transfer single, range or all data points to printer or computer
Yes, selectable
pH, mV, relative mV (RmV) or ORP with temperature
-5.0°C to +105.0°C
24cm x 10cm x 6.5cm (9.5 in. x 3.9 in. x 2.6 in.)
0.5 kg
1 point temperature offset calibration
±2000.0 mV
±0.2 mV or ±0.05% of reading whichever is greater
10 per channel with password protection
-2 to 20
1000 with date and time stamp
41°F to 113°F (ambient)
5 to 85%, non-condensing
CE, TUV 3-1, FCC Class A
Comprehensive with menu-specific function keys and dual purpose scroll/shortcut keys
pH electrode, ORP electrode, reference half-cell electrode, ATC temperature probe (includes 8107UWMMD ROSS Ultra Triode pH/ATC electrode)
IP 67
Non-volatile memory preserves data log, calibration log and meter settings
Orion Star A221 pH/mV/RmV/ORP/Temperature Portable Meter
Smart Stability and Smart Averaging
Universal AC adapter (included) or 4 AA batteries (sold separately)
Automatic data logging with Auto-Read measure mode; manual data logging with Continuous measure mode
pH, relative mV (RmV), ORP and temperature
USB, RS-232
BNC (pH or ORP electrode), pin-tip (reference electrode), 8 pin MiniDIN (ATC temperature probe)
0.1°C, 0.1°F
±2000.0 mV
±2000.0 mV
1 to 5
1.2 lb.
22.0°F to 221.0° F
4 x AA
3 Year Meter
800 hr.
5°C to 45°C (ambient)
Calibration due alarm (fixed 12 hour)
English, Spanish, French, Italian, German and Chinese; Portuguese and Korean available with software update
LCD Graphic, Backlit
Manual or automatic with ATC temperature probe
Orion Star A221 pH portable meter kit with ROSS Ultra Triode low maintenance gel pH/ATC electrode, solutions, meter armor and field case
Star A221 pH meter, 8107UWMMD ROSS Ultra gel-filled epoxy-body pH/ATC electrode with 3m cable, pH 4/7/10 buffer and rinse pouches, ROSS storage solution, protective meter armor, hard-sided carrying case, 4 AA batteries, computer cable
Universal 50-60 Hz, 100-240 VAC power adapter (sold separately, Cat. No. 1010003)
Product Certifications


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