Conductivity Transmitters G Instruments designs and manufactures highly accurate and reliable conductivity transmitters. GCT20K is a field programmable conductivity transmitter with a high accuracy, flexibility and reliability. Features Isolated loop power 4-20 mA output with reverse polarity and surge protection Resolution better than 2 uS/cm The transmitter is built-in the head of the probe - it is just the probe and a thin cable coming out of it Tripple isolation - the electrodes are isolated from the 4-20 mA output and the power. The power is also isolated from the 4-20 mA output Potential free electrodes - the measurement does not change or polarize the liquid Field programmable from 0 to 20 000 uS/cm. Both the conductivity for 4 mA and 20 mA are programmable - the output can be moved up/down, scaled or inversed Field programmable reference temperature Field programmable temperature coefficient from 0.00 to 10.00 % / oC 10 points curve for the temperature coefficient Switching from single TempCo to the curve at any time in seconds Operating temperature, liquid: -20 to +120 oC Ambient temperature, electronics: -30 to +80 oC Kynar PVDF body and graphite electrodes ensure very high chemical and wear resistance Platinum RTD ensures very accurate temperature measurement and compensation IP67 (NEMA-6) protection on the electronics GCT20K-MB is a RS485 MODBUS RTU conductivity transmitter with a high accuracy, flexibility and reliability. same as GCT20K except it has a fully programmable and fully compliant, isolated RS485 MODBUS RTU instead of 4-20 mA analog output 1/8 load allows up to 247 devices to be connected on the same 2-wire network resolution 1 uS/cm temperature, conductivity, temperature coefficient, reference temperature, curve points and other parameters can be read many times a second or written.