Conductivity: 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.

Conductivity measurement

The MSV77 and MFD77 devices support conductivity measurements using two-electrode and four-electrode sensors on a total of six ranges. (However, we recommend using the more advanced MFD80 portable device, whose improved conductivity input supports an extended and continuous measurement range with a single sensor, as well as conversion of output data to TDS or salinity and other enhancements.)

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).

Dimensions200 x 45 x 150 mm
Weightca 0.5 kg
EnclosureIP 40
Power supplyMains adapter (9V AC, 300 mA)
Data log capacity16000 values
Digital interfaceRS-232
Analog output0 - 2 V
Recommended conductivity sensorsvariants of type C21 (multiple options - on request) suitable for range 0.01 µS/cm - 2000 µS/cm, with platinum black up to 100 mS/cm
Conductivity measurement range0.1 µS/cm - 500 mS/cm (divided into 6 ranges)
Conductivity measurement accuracy± 2 % (of full range)
Temperature correction for conductivity measurementLinear coefficient 0 - 15 %/°C
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