pH and ORP: Desktop instruments 77
The instruments of the 77 series are classic desktop devices suitable primarily for use in the laboratory. Their advantages include a convenient shape, mains power supply, data and analog output and a wide range of available measurement types. There are several variants equipped for simultaneous measurement with different groups of supported sensor types.
Operation of the device is easy thanks to the high-contrast dot-matrix LCD display, which is easy to read in the dark and in the sun, and a simple menu-based system controlled by a few buttons. Access control with a password protects the device against unwanted changes to settings, or against unwanted interventions by less qualified operators or unauthorized persons. Semi-automatic calibration procedures greatly facilitate the preparation for measurements.
The built-in data logger can record up to 16,000 time-stamped readings. The resulting record may be transferred to a computer for further processing via the RS-232 data interface. The analog output enables the currently measured data to be transferred to classic analog recorders or similar devices.
Please consider also our more advanced alternative - the MFD80 portable device, which offers USB interface, support for oxygen measurements with an optical sensor, better resolution for ISE measurements, improved conductivity measurement, battery power, compact dimensions suitable also for field work, and a number of other improvements.
pH and ORP measurements
The MPH77, MPI77, MFD77 and MFD77PHK instruments offer two inputs for simultaneous pH and/or ORP measurements (one input in the MPH77E cost-saving variant). Classic glass sensors with an integrated reference electrode are usually used for pH measurement, but a pair of separate pH / reference electrodes may also be connected. Temperature correction of pH measurement is available with an additional temperature sensor connected. ORP can also be measured through the same input of the device if a corresponding sensor is connected.
Additional measurement of temperature and atmospheric pressure
Devices of the 77 series also support up to two inputs for nickel-based temperature sensors (type TNiK115), intended especially for temperature correction of pH or conductivity measurement. Another temperature sensor is integrated in the oxygen sensor and is used for temperature correction of the oxygen measurement.
Devices equipped with an input for measuring oxygen may also include an atmospheric pressure sensor, the data of which is primarily used to correct the oxygen measurement.
Multi-parameter devices
Variants equipped to support several different sensors are also available: The MFD77PHK (measurement of pH, ORP and oxygen concentration) and MFD77 (full set of available measurements).
| Dimensions | 200 x 45 x 150 mm |
| Weight | ca 0.5 kg |
| Enclosure | IP 40 |
| Power supply | Mains adapter (9V AC, 300 mA) |
| Data log capacity | 16000 values |
| Digital interface | RS-232 |
| Analog output | 0 - 2 V |
| pH measurement range | 0 - 14 |
| pH measurement accuracy | ± 0.02 (at 25 °C) |
| ORP measurement range | ± 1000 mV |
| ORP measurement accuracy | ± 1 mV |
| Temperature measurement range with TNiK115 sensor | -5 to +100 °C |
| Temperature measurement range with CSOT43L sensor | -4 to +40 °C |
| Temperature measurement range | ± 0.2 °C |