Orion Star A325 pH / Conductivity Portable Meter

  • High Range pH Applications pH measurement range from -2.000 to 20.000
  • High Range Conductivity Applications Conductivity measurement range from 0.001 mS to 3000 mS
  • Non-Volatile Memory Memory capacity to store up up 5000 time and date stamped data points
  • Warranty A325 is covered by a 3 year replacement meter warranty
Product Options


With the Star A325 Portable Water Quality Meter, information is easy to read of the large backlit graphic LCD display which shows individual pH/mV/RmV or conductivity/TDS/salinity/resistivity results with temperature or all results at once. Laboratory accuracy can be sought with the advanced salinity and averaging options. Conductivity readings with advanced accuracy are given by selecting a reading reference temperature of 5, 10, 15, 20 or 25°C with the choice of linear, non-linear, nLFu or EP curve.

Up to 5 point pH calibration with automatic recognition for USA/NIST and DIN buffers, selectable cell constant enables use with 2 or 4 cell conductivity cells. Practical salinity or natural sea water curves specifically for salinity readings can be set and Linear or ISO/EN 27888 curves for TDS. pH calibration errors can be fixed without the need for a complete recalibration using calibration editing. Further on screen features include electrode status, time, date, sample ID, user ID and calibration points.

The Orion Star A325 pH/Conductivity Portable Water Quality Meter has the capacity to hold up to 5000 data points time and date stamped. Additional on screen features include electrode status, time, date, sample ID, user ID and calibration points. Multilanguage supports in English, Spanish, French, Italian, German and Chinese, clear language prompts and soft key updates make this meter easy to use.

Updating and transferring of information is simple using the USB, RS23 ports and complimentary data analysis software. The AUTO-READ feature means stable readings are locked on the screen and the ready indicator advises when readings are stable. Timed readings gather information at specific time intervals for added accuracy.

The water quality meter is waterproof, protected with IP67-rated housing and can be powered either with batteries or a universal power adapter sold separately and covered by a 3 year replacement warranty.

Manufactured by: Thermo Scientific
Model: Orion Star A325 pH / Conductivity Portable Meter

Services offered for this product

  • Sales
  • Rental
  • Installation
  • Calibration
  • Maintenance


High range applications
Seawater applications
Saline ingress
Estuary monitoring


Range -2.000 to 20.000
Resolution 0.1, 0.01, 0.001
Relative Accuracy ±0.002
Calibration Points Up to 5
Calibration Editing Yes
Range ±2000.0 mV
Resolution 0.1
Relative Accuracy ±0.2 mV or ±0.05 % of
reading whichever is greater
EH ORP Mode Yes
Range 0.001 µS to 3000 mS
Resolution 0.001 µS minimum;
4 significant figures minimum
Relative Accuracy 0.5 % reading ±1 digit
Reference Temperature 5, 10, 15, 20, 25 °C (default)
Linear (0 to 10.0 %/°C),
nLn, nLFu, EP
Cell Constants
0.001 to 199.9
Calibration Points Up to 5 points
Calibration Editing Yes
Range 2 ohm to 100 meg-ohm
Resolution 2 ohms-cm
Relative Accuracy 0.5 % reading ±1 digit
Type Practical salinity or natural sea water
Range 0.01 to 80.0 ppt NaCl equivalent;
0.01 to 42 ppt practical salinity
Resolution 0.01
Relative Accuracy ±0.1
Range 0 to 200 ppt
Resolution 4 significant digits
Relative Accuracy ±0.5 % reading ±1 digit
TDS Factor Range Linear 0.01 to 10.00, default 0.49
Range -5 to 105 °C, 23 to 221 °F
Resolution 0.1
Relative Accuracy ±0.1
Offset Calibration 1 point
Number of Points 2000 with time and date stamp
Log Function Manual, ready (include AUTO-READ™), timed
Log Edit Delete individual points, group of points or all
pH Electrode BNC, reference pin
Conductivity with
Temperature Probe
or ATC Probe
8-pin mini-DIN
Output RS232, USB
AC Adapter Optional universal, 100-240 VAC
Battery Power Included 4 AAs
Battery Life 800 hrs