In this article, we will explain a most versatile instrument used in industry today – the Pressure Transmitter.

### Transmitter

A transmitter is a device that converts the electrical signal from the transducer into a compatible electrical signal that can be sent over a long distance to a PLC or a DCS. The transmitter output signal is usually a range of voltage (1 to 5 V) or current (4 to 20 mA) which represents the 0 to 100% of the actual sensed physical measured variable.

### Pressure Transmitter

A Pressure Transmitter is an instrument connected to a Pressure Transducer or directly to sensor. The output of a Pressure Transmitter is an analog electrical voltage (0-5V) or a current signal (4-20mA) representing 0 to 100% of the pressure range sensed by the sensor or transducer.

The real part of the transducer that makes contact with actual pressure is based on a lot of technology and building materials such as Strain Gauge, Capacitance, and Potentiometric.

The type of sensor selected is determined by the application and the environment in which it is used.

Pressure measurement can be absolute pressure, gauge pressure, or differential pressure.

Absolute pressure

Absolute pressure is referenced to a perfect vacuum which is normally called 0 psi! We express vacuum pressure as 0 psi (a) and Atmospheric pressure is usually about 14.7 psi (a).

Gauge pressure
The most common pressure measurement is gauge pressure which is the total pressure minus the atmospheric pressure. Atmospheric pressure is 0 psi (g).

Summary

• Please note Transducer is a device that converts one form to another.
• A transmitter is a device that converts an electrical signal from a transducer to a larger electrical signal that can be transmitted over long distances to the PLC or DCS.
• Pressure Transmitter is a device connected to the Pressure Transducer.
• Pressure Transmitter output is an analog electric current or current signal representing 0 to 100% of the pressure range generated by the transducer
• Pressure transmitters can measure absolute, gauge, or differential pressures.