Pressure transmitter or transducer?

A pressure transmitter is the device that transmits a measured pressure to another element or system via analog signal or some communication protocol.

A pressure transducer is virtually the same thing (by some definitions) but if you look at what a transducer is (on its own) it is a device that converts energy from one form to another.

So as far as I am concerned, a PRESSURE TRANSDUCER is the device housed inside the pressure transmitter, which has the function of converting the physical pressure into a electrical signal that can be used for calculations and/or simply to be amplified and transmitted by the transmitter as stated above.

Pressure Gauges

WIKA Pressure Gauge

Just so we’re clear, shown above are some examples of a pressure GAUGES.  The technology housed behind the face of the gauge is called a Bourdon tube connected to a spring.  The following schematic show what it looks like.  I will not go into the details of how it works – this will be covered in another blog post.

Bourdon Tube courtesy of InstrumentToday.com

 

Pressure transmitters

Pressure transmitters come in different shapes, sizes and designs with almost endless options (process connections, chemical seals, diaphragm types, communication capabilities and so on) for different applications (perform different tasks depending on the process/environmental requirements).

  • Differential Pressure transmitters (see more on a DP cell in a previous post)
  • Gauge Pressure Transmitters (atmosphere reference pressure)
  • Absolute Pressure Transmitters (vacuum reference pressure)
Google’s answer to “How does a pressure transmitter work?” is: “A pressure transducer, often called a pressure transmitter, is a transducer that converts pressure into an analog electrical signal. … Pressure applied to the pressure transducer produces a deflection of the diaphragm which introduces strain to the gauges.”  The gauges referred to here are strain gauges (resistors) that measure the expansion and contraction of the pressure transmitter’s diaphragm.
Here are some examples of different pressure transmitters (or transducers if you will):
Yokogawa Pr Tx with screw on
Endress+Hauser Pr Tx with flange

 

Rosemount Pr Tx with manifold

Here are some pressure transmitter manufacturers (there are many – these are just a few of the biggest):

Related post: The STEM in a Pressure Transmitter (future post)

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