Pressure Indicating Transmitter
Pressure indicating transmitter, abbreviated as PT and PIT, is an instrument for measuring, controlling and indicating positive, negative or differential pressures of different fluids. Depending on the configuration, a pressure transmitter may output the gauge pressure or the absolute pressure. Pressure indicating transmitters display the pressure the operator and convert the signal to be sent to an external destination. Pressure transmitters do not contain a local display.
Inputs: Pressure transmitters can be loop powered or externally powered. Typically the AC voltages are 120 volts or below. DC voltages range as high as 42 VDC.
Outputs: Output can be 4-20mA, Fieldbus, DeviceNet or mV.
Depending on the process, it can be mounted directly to the process or remotely mounted. Remote connections can be mounted on a DIN rail or on a pipe for indication. Some pressure transmitters have a built in pressure sensor and some require a separate sensor.
Process connections are typically made of several different materials. 316L SST, Hastelloy, Monel. When using a pressure transmitter, it should be mounted on a manifold valve to allow the transmitter to be removed while it is in service.
New, high end pressure transmitters allow you to customize performance, functionality, diagnostics, and connection systems depending on your application. Other transmitters have the ability to output the signal directly into your companies intranet or internet. Wireless transmitters such as those in the PlantWeb family are being utilized more frequently in plant applications where it is cost prohibitive to run wire and communications cable.
Some of the more accurate pressure transmitters are used in hydrotest applications. The 4-20 mA signal may be conditioned and data points stored directly within the transmitter or they may output the signal into an external data logger.