- Liquid level measurement in a closed vessel. Level is proportional to the bottom liquid pressure minus the top ambient (gas or air) pressure.
- Liquid blending control. Must maintain a zero difference between two measured flow rates.
- Relative speed control. Control for zero difference between two speed measurements.
The figure shows two voltages, both grounded. The signals may come from two pressure or flow transmitters, tachometers or other sources. The isolator's input is connected between the two positive voltages; thus, the input is (V1 - V2). Its output may be set to equal the differential input or it may be scaled up or down, offset or converted to a current signal such as 4-20mA.
We offer plug-in, DIN rail and field mount style isolators and transmitters.
Links: Add/Subtract Transmitter Modules
DIN-Rail style add/subtract transmitters
All Process Transmitters and Alarms