Reliable pH and ORP checks depend on stable readings, clear handling and the right electrode connection. The GMH 35x1 family supports portable water analysis, laboratory checks and field measurements with pH, ORP and temperature measurement in one handheld platform.
Users can measure from 0.00 ... 14.00 pH, -1999 ... +2000 mV and -5.0 ... +150.0 °C with device accuracies of ±0.01 pH, ±0.1 % FS and ±0.2 °C in the -5 ... +100 °C range. A connected Pt1000 probe enables automatic temperature compensation for pH and mVH measurements, while the BNC socket supports suitable pH or ORP electrodes for different media.
Daily work is kept practical with automatic buffer detection, electrode quality rating and a two-line LCD display. Depending on the model, the family adds rH measurement, calibration reminders, calibration history, scalable analog output and a data logger for up to 10,000 cyclic data sets or 1,000 manual data sets.
The family measures pH, ORP in mV and temperature with suitable electrodes. GMH 3531 and GMH 3551 also provide rH calculation from pH and ORP measurement.
A BNC socket accepts pH or ORP electrodes, while 4 mm banana sockets connect a Pt1000 temperature probe. Electrodes with integrated temperature sensors can also be connected.
The devices support automatic buffer detection and electrode state rating. GMH 3511 uses 2-point calibration with GPH buffer capsules; GMH 3531 and GMH 3551 support 1-, 2- or 3-point calibration with GPH, PHL, DIN 19266 or manual buffers.
Two 4-digit LCD displays show the main measured value and temperature. Min, max and hold functions support direct reading checks during portable measurement.
The universal output can be used as a serial interface with suitable isolated adapters or as a 0 ... 1 V analog output. GMH 3551 offers freely scalable analog output.
GMH 3551 adds manual and cyclic data logging. The logger records measured value, temperature, time and date, with measuring point input available for manual recordings.
The instruments operate with a 9 V battery and include a socket for an external 10.5 ... 12 V DC power supply. Battery life is approximately 300 h.
The integrated pop-up clip allows the handheld unit to be laid flat, set up on a table, attached to a belt or suspended from a suitable holder.
