Orion™ 261S Basic Waterproof Portable pH Meter

General Details

Measure pH, mV and temperature in environments where non-sparking equipment is required using the Thermo Scientific™ Orion™ 261S Intrinsically Safe (US) Portable pH Meter. Intrinsically safe approval rating by Factory Mutual (FM) for US only.

Description Orion Intrinsically Safe 261S pH portable meter
Model Orion Intrinsically Safe 261S pH/mV/Temperature Portable Meter
Item Description Orion Intrinsically Safe 261S pH portable meter
Includes Orion 261S pH meter, 3 AA batteries
Range (pH) -2.00 to 16.00pH
Resolution (pH) 0.1, 0.01pH
Accuracy (pH) ±0.01pH
Range (mV) ±1300.0mV
Resolution (mV) 0.1mV
Accuracy (mV) 0.1% of reading ±0.3 mV
Calibration pH
Calibration Points (pH) 1 to 3
Range (Temperature) -20° to 120 °C, -4° to 248° F
Resolution (Temperature) 0.1°C
Accuracy (Temperature) ±0.3°C
Temperature Selection Automatic with ATC temperature probe
Channels 1
Display Type LCD
Keypad Measure, cal, scroll up, scroll down, power keys
Measurement Modes pH with mV and temperature
Languages English
Inputs E-DIN Waterproof (pH electrode), banana plug (ATC temperature probe)
Outputs None
Probe Type pH electrode, ATC temperature probe (purchase separately)
Power Supply 3 AA batteries (included)
Battery Life 1000 hours
Battery Type Three AA (included)
IP Rating IP-66
Certifications/Compliance CE, FM (IS, Class I Div 1 Group A, B, C, D, T4), Ex (Intrinsically Safe)
Temperature (English) Operating 14° to 131°F (ambient)
Temperature (Metric) Operating -10° to 55°C (ambient)
Dimensions (L x W x H) 16cm x 13.3cm x 3cm (6.30 in. x 5.24 in. x 1.18 in.)
Weight (English) 1.4 lb.
Weight (Metric) 0.6kg
Backlight Option None
Warranty 3 year meter warranty
  • 2.00 to 16.00pH range
  • -20° to +120° temperature range
  • ±1300mV range
  • Safely measure in hazardous and confined space environments and anywhere nonsparking equipment is desired
  • Battery-operated
  • Large, easy-to-read display to monitor electrode condition, calibration status and pH, mV and temperature readings
  • Automatic or manual calibration with up to three calibration points


  • Meter Only package includes meter, built-in quiver, neckstrap and instruction manual
  • Meter/Electrode package includes meter, Triode™ 3-in-1 Combination pH Electrode, built-in quiver, neckstrapand instruction manual
  • Meter Field Kit package includes meter, built-in quiver, neckstrapand instruction manual, case, stand, electrode holder, beakers, 4, 7, 10 buffers, RS232 cable and software