Which component is essential for the operation of a pneumatic transmitter?

A pneumatic transmitter relies on compressed air to transmit signals, making an air compressor an essential component for its operation. The transmitter uses the pressure variations generated by the compressed air to represent measured values such as temperature, pressure, or flow.

When the variable being measured changes, it alters the volume and pressure of the air in the transmitter, which is then converted into a proportional output signal. This process is fundamental to how pneumatic transmitters work, as they utilize the principles of pneumatics to effectively communicate measurements in control systems.

The functionality of a pneumatic transmitter directly depends on the availability of compressed air, thus emphasizing the importance of an air compressor in its operation. The other components listed do not directly contribute to the generation and control of pneumatic signals in transmitters.