A pressure transmitter is a simple device based on a simple principle that can be used to measure more than pressure: level, and flow for example. To do this, we need some other devices as well. The value proposition of a multivariable pressure transmitter is that it replaces all of them.

Installing a multivariable pressure transmitter

We can install a multivariable pressure transmitter in all kinds of applications, but all of these take different installations. For example, if we want to measure level with a differential pressure transmitter and if we have an open tank, then we can install the device on the bottom of the tank using a flange with a filled-sealed container.

To know more about pressure, you can read our article on pressure measurement and calibration

A multivariable pressure transmitter has the ability to replace multiple other instruments in the plant by measuring multiple pressure variables. Earlier, to measure flow using a differential pressure transmitter, we had to combine elements – differential pressure transmitter, static pressure transmitter, temperature sensor, local indicator, and a computer to collect and calculate everything.

Cerabar PMC21 Pressure transmitter with ceramic sensor for measuring absolute or gauge pressure

We still can find this sort of solution in the market, and depending on our needs it may be enough, for example, if we already have some of its parts in place. However, it costs more than a multivariable pressure transmitter because it needs more structure, devices, and time to set up.

A multivariable pressure transmitter offers all these features in a single device: differential and static pressure sensors, and an easy way to connect a temperature sensor. The multivariable pressure transmitter will measure mass flow accurately while requiring less structure and time to set up and run.

To know more about measuring level with differential pressure transmitters, you can read our article here

While multivariable pressure transmitters are great for measuring flow with pressure, it’s worth noting that now there are more specialized flow measurement devices that perform better. For steam measurement, for example, it usually makes more sense to use a vortex flow meter.

Reading the values of a multivariable pressure transmitter

A multivariable pressure transmitter will measure static pressure, differential pressure, and temperature.  If you have a digital protocol like HART, then you can read this data using the primary variable (PV), secondary variable (SV), tertiary variable (TV), and quaternary variable (QV).

If you don’t have HART or some other digital protocol, then you can buy a device to split this data for more than one analogue output. The market has several brands offering devices for signal conversion.

Basically, the converter will read the data in the PV, SV, TV, and QV and dedicate one output to each. The Triloop from Emerson can give you up to three outputs, and Pepperl+Fuchs has a similar device.

On one hand, this sort of solution comes up a lot for multivariable meters in analogue systems. On the other, it still doesn’t offer you the best way to get your data. Digital communication gives you the best of the worlds, so if you have it, then try it. It might surprise you.

If you need help choosing the right multivariable pressure transmitter for your application, take a look at our new pressure smart assistant.

To know more about multivariable pressure transmitter, you can get in touch with our engineers and we will be happy to help.

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