Emerson Model 3051s Multivariable HART Transmitter

It depends upon what is written in the Control Philosophy document, which cannot be seen from here. If it has to do some form of action, then the details of that action, and the actuated device, need to be described.

...and make sure the proposal passes through a HazOp Study before implementation.

The multivariable can definitely provide a process variable to a control loop in the form of an instantaneous gas mass flow rate value.

If a model version is available with Foundation Fieldbus (FF) communications and the supporting FF infrastructure is also available, then it is possible for a PID control block in an FF field instrument to perform a control function, communicating to valve with an FF positioner.

Whether FF is available on this particular model, I don't know, and of course, there are other FF components in an FF control loop.

Assuming all elements are in place per the other previous posts.

Pressure transmitters are used to control back pressure very frequently. However, as impressive as Emerson makes this unit sound, (I've watched the video clip on this model and have used it) this is just a pressure transmitter, a multiple use re-configurable transmitter, but still just a transmitter. Somewhere some artificial intelligence is going to have to be involved to interpret the pressure signal and compare to the desired pressure, then control a regulating valve. (you did not say if your back pressure regulator was electrical/pneumatic or strictly mechanical)

So you will need a PLC or some micro-processor to feed the pressure signal to, and a regulating valve for the PLC or micro-processor to send signal to for control, and the ability to program the intelligence to perform what you want it to do.

What i want to know is, We have a Multivariable Transmitter that is hooked-up to the Upstream & downstream of a Daniel Senior Orifice box and gets signal from a PLC; and will be used to measure flow. Can this same transmitter be used/configured to control the Back pressure control valve of the same vessel since it has a static pressure range of 0-500psi?

Yes, though why bother (rhetorical question - NNTR) since other pressure regulating equipment needs to be in place in case of power failure. That is why a HazOp Study needs to be carried out at the facility before the scheme is implemented.

Do it once, and do it right.

A multivariable measures multiple variables, one of which is static line pressure on the upstream, high, side.

That is done in other brand multivariables as absolute pressure, not gauge pressure, but I suspect Rosemount does absolute as well.

Multiple variables can be brought out of a HART version multivariable transmitter with Rosemount's Triloop adapter or Moore Industries HIM break-out box, either of which takes the HART variables on the transmitter's 4-20mA output and converts each to an analog output. (Moore might do 4, Triloop does 3)

So, yes, you can get a static line pressure output from a multivariable, but you might have to subtract a constant (roughly 1 atmosphere) if you need gauge pressure