Tag
#transmitter
3 topics across all disciplines.
What a transmitter is, and why it sends 4–20 mA
How a field instrument turns a physical quantity into a number the control room can use, why the signal starts at 4 mA instead of zero, and how to pick a measurement principle.
Measuring flow — orifice plates and the alternatives
Why most flow measurement is really a pressure measurement, what the square root relationship means for turndown, why straight lengths are a measurement requirement rather than a layout preference, and how to choose between orifice, vortex, magnetic, Coriolis and ultrasonic meters.
Measuring level — why most level readings are really weight
How differential pressure, displacers and radar each infer level, why a wet leg that partially drains makes the tank read full, what a bridle is for and how it lies on hot service, and why a gauge glass disagreeing with the transmitter is information rather than a nuisance.