Different terms are used in the compressor industry when referring to pressure transducers that measure from negative to positive gauge pressure. Measuring both suction and discharge, a compound pressure transducer provides a linear output signal from full vacuum through zero pressure up to the full scale pressure.A pressure transducer with a pressure range of -14.7 to 30 PSIG can be referred to as a compound pressure transducer, 30V30 (referring to -30″ of mercury) transducer, or a vacuum to 30 PSIG sensor. While the terminology differs, it can refer to the same product. Calculating the offset of the pressure transducer as it should read with no pressure (or the pressure on the bench) can be confusing without writing it down.
Here are a couple of examples to help walk you through the process for both 4-20mA output signals and voltage signals. The same principles apply to other pressures and output signals. We started with a pressure measurement range of -14.7 to 15 PSI to help visualize how the calculation should work. While 0 PSI is close to the mid-point between the output, it is not exact; a few extra steps lead us to the right reading.
AST Sensors
www.astsensors.com
