Pressure transducers are commonly used for detecting and measuring process variables like temperature, level, composition and flow, and transmit a constant analogue output signal. These output signals can be current, voltage or proportional pneumatic. They are used for recording, indication, control and data acquisition systems.
Different types of pressure transducers are available for measuring the vacuum pressure, differential pressure, static pressure and the derived variables like partial pressures of gases and vapours.
How pressure transducers work
Pressure transducers determine a pressure, and convert it into a proportional output signal. This output signal can then be transmitted to a remote location. For instance, if the calculated pressure range is 0-100 psi (pounds per square inch) with an output range of 0-5 volts DC proportional to that range, the output signal of 50 percent full range, or 2.5 volts would indicate a 50 psi pressure value.
The calibrated voltmeter display would read 50 psi, and not 2.5 volts. In the past, transducers used diaphragms, bellows and bourdon tubes in motion balance systems like slide wires, capacitance and variable resistors. Most transducers available today use high-accuracy, solid-state capacitance, piezoelectric or strain gage sensing principles.
Types of pressure measured
Pressure transducers come with a pounds per square inch gauge (psig). This is a positive pressure compared to the absolute, atmospheric pressure like the differential pressure and pounds per square inch absolute (psia). Pressure transducers compare two different pressures and transmit a proportional output, vacuum pressure – a negative pressure compared to the atmospheric pressure.
