InPro 3250 Series pH Probes for High Performance & Accuracy

InPro 3250, 3250SG & 3250i pH Probes

Pre-pressurized liquid-electrolyte probe with temperature sensor

The low-maintenance pH probe InPro 3250 series with factory-filled, pre-pressurized liquid electrolyte are suited to an extensive range of applications in the biotechnology, pharmaceutical and chemical process industries. The InPro 3250 series is available with a wide selection of different pH-sensitive glass membranes. This ensures the best possible measurement performance under the most diverse operating conditions.

Features and Benefits

  • Long operational sensor lifetime and high accuracy
  • Intelligent Sensor Management (ISM®)
  • Easy validation
  • Solution ground (SG) as an option
  • More precise pH measurement


Specifications - InPro 3250, 3250SG & 3250i pH Probes
Short description Sterilizable, pre-pressurized, liquid-electrolyte pH probe with temp. sensor
pH range 0...14 (InPro 3250); 0...12 (InPro 3253)
Temperature range 0...140 °C (32...284 °F)
Pressure resistance (bar) up to 4 bar overpressure
Pressure resistance (psi) up to 58 psi overpressure
Diaphragm ceramic
Number of diaphragms 1
Reference system Argenthal system
Solution Ground optional InPro 3250SG and InPro 3253SG
Silver-ion trap yes
Sterilizable yes
Autoclavable yes
ISM yes
ATEX Certification SEV 14 ATEX 0168 XEx ia IIC T6/T5/T4/T3 Ga/Gb
IECEx Certificate of Conformity IECEx SEV 14.0025XEx ia IIC T6/T5/T4/T3 Ga/Gb
FM approval IS/ I, II, III /1 /ABCDEFG /T6
Features and Benefits
Long operational probe lifetime and high accuracy
  • The probe is provided with a patented silver-ion trap to prevent diaphragm fouling in sulfide-containing media. The internal over-pressure ensures gradual electrolyte outflow, efficiently cleaning the diaphragm and preventing influx of process medium into the reference electrolyte.

 Intelligent Sensor Management (ISM®)

  • ISM simplifies and improves the operation of process analytical systems from initial installation to maintenance to sensor exchange. ISM technology provides you with advanced diagnostic functions, lower maintenance costs and reduces the risk of sensor failure, while also improving process reliability. More information about ISM
Easy validation
  • The InPro 3250(SG) series offers a set of customized certificates for each application, including certificates for hazardous zones, biocompatibility of the electrolyte, and all relevant hygiene and safety regulations.
Solution ground (SG) as an option
  • The SG feature as an entire electrode body coating or as a measuring point on a pH probe improves grounding and effectively eliminates the risk of electrostatic interference. SG also allows the use of our advanced diagnostic functions, and makes parallel pH/redox measurement possible.
More precise pH-measurement
  • A wide selection of different pH-sensitive glass membranes ensures the best possible measurement performance, for example, by minimizing zero point shift following sterilization in biotechnology applications.

InPro 3250SG Series is available as an option equipped with a solution ground for redox measurement, for enhanced diagnostics, or for avoiding ground loops. Custom-tailored pH-glass membranes are available for chemical applications (InPro 3250) and processes in biotechnology and pharmaceutical industries (InPro 3253).




Application Note: Improve Your Processes with ISM
In many ways, analytic measurements are at the heart of your process efficiency. Therefore, the lower your downtimes and maintenance requirement, and...
Application Note: Improve Your Pulp & Paper Process Further with ISM Technology
Many years of experience in the field of industrial measurement systems form the basis of METTLER TOLEDO’s competence. Now with its ground-breaking IS...
Easy ISM Sensor Management in Breweries
Application Note - iSense ISM Asset Suite the professional software tool to implement innovative and efficient maintenance concepts with pre-calibrate...
Get Your Quote
InPro 3250, 3250SG & 3250i pH Probes
USP Class VI


Get Your Quote
InPro 3250, 3250SG & 3250i pH Probes
USP Class VI
Thank you for visiting We have tried to optimize your experience while on the site, but we noticed that you are using an older version of a web browser. We would like to let you know that some features on the site may not be available or may not work as nicely as they would on a newer browser version. If you would like to take full advantage of the site, please update your web browser to help improve your experience while browsing