What is the typical constant air supply pressure received by pneumatic transmitters?

Pneumatic transmitters are devices that utilize compressed air for the transmission of signals in control systems, particularly in industrial applications. The typical constant air supply pressure for these transmitters is generally around 140 kPa. This pressure level is significant because it provides sufficient energy for the operation of the transmitter while ensuring optimal performance and accuracy in signal transmission.

A supply pressure of 140 kPa falls within the range that pneumatic systems are designed to operate efficiently. It allows for the effective movement of pneumatic signals without introducing excessive stress on the transmitter components. Additionally, this pressure helps maintain a good signal-to-noise ratio, which is crucial for reliable operation, especially in environments with various interferences.

While other pressures listed may exist in specific scenarios, 140 kPa is widely recognized as the standard pressure for pneumatic transmitters, making it the correct answer. The other pressures can either be too low to ensure proper function or too high, which could lead to potential damage or incorrect readings in the pneumatic system.