In this video,
we’re going to introduce you to a very versatile instrument used in industry today
the “Pressure Transmitter”.
Alright…let’s go.
First of all, let’s discuss the terms “Transducer” and “Transmitter”.
Some people will tell you that a Transducer and a Transmitter
are the same thing
and therefore the terms are interchangeable.
If you are curious, conduct a web search of the two terms
and you will be surprised at the wide range of results!
A transducer is a device that converts one form of energy to another.
For example, an electrical transducer
converts a sensed physical variable like temperature
into an analog electrical signal.
A transmitter is a device
that converts the electrical signal from the transducer
into a much larger 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 Volts.
or current, 4 to 20 milliAmps
which represents the 0 to 100% of the sensed physical variable.
A Pressure Transmitter is an instrument connected to a Pressure Transducer.
The output of a Pressure Transmitter
is an analog electrical voltage or a current signal
representing 0 to 100% of the pressure range
sensed by the transducer.
The actual sensor part of the transducer
which makes contact with the pressure being sensed
is based on several technologies and materials
such as “Strain Gauge”, “Capacitance” and “Potentiometric”.
The actual process is separated from the sensing material
by a measuring diaphragm.
The type of sensor chosen is decided
by the application and environment it is being used in.
Pressure transmitters can measure absolute,
gauge, or differential pressures.
Absolute pressure is referenced to a perfect vacuum
which is considered 0 psi!
We express vacuum pressure as 0 psi (a)
Atmospheric pressure is usually about 14.7 psi (a).
The most common pressure measurement is gauge pressure
which is the total pressure minus the atmospheric pressure.
Atmospheric pressure is 0 psi (g).
As we’ve discussed in our previous videos,
the versatility of a differential pressure transmitter
gives us the flexibility to measure level and flow
as well as pressure.
Let’s have a look at an example of a Pressure Transmitter
measuring process pressure of gasses in a pipeline.
The Pressure Transmitter will send a current signal to the PLC
which represents the process pressure.
The Pressure Transmitter is calibrated to provide a current range of 4 to 20 mA
for a Process Pressure range of 0 to 350 psi.
If you want to learn more, you might want to review 2 of our other videos,
“What is a Pressure Sensor?”
and “Differential Pressure Transmitter Explained”.
You can find the links to these videos in the description.
Ok…let’s summarize what we’ve discussed today…
Some people will tell you that a Transducer
and a Transmitter are the same thing
and therefore the terms are interchangeable.
A transducer is a device that converts one form of energy to another.
A transmitter is a device that converts the electrical signal from the transducer
into a much larger electrical signal
that can be sent over a long distance to a PLC or a DCS.
A Pressure Transmitter
is an instrument connected to a Pressure Transducer.
The output of a Pressure Transmitter
is an analog electrical voltage or a current signal
representing 0 to 100% of the pressure range sensed by the transducer
Pressure transmitters can measure absolute,
gauge, or differential pressures.
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