Expert’s answer : How to read the process variable from a multivariable flow meter

A differential pressure (DP) multivariable meter 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 analog 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.


Rosemount™ Tri-Loop™ – Courtesy of HART

On one hand, this sort of solution comes up a lot for multivariable meters in analog 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.

Below you can find out more about DP flow meters and digital protocols:

Differential pressure transmitter in flow measurement

Pressure transmitters are really versatile, and we can use them to measure other things besides pressure. In fact, we used them a lot in measuring level and flow for more than a decade. However, new tech in flow and level measurement have begun to edge out the old pressure solutions.


If you  want to know if you should go for FOUNDATION Fieldbus or HART? Here you could find the  reviews of  both technologies. Then you could decide which will suit your needs best.

Is there a difference between HART and fieldbuses?

Is there any difference between a HART and other fieldbuses? if I have a HART network, will I receive less information than if I used, for example, a FOUNDATION Fieldbus device? The answer is in the article.

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