E+H Hart transmitters on a ControLogix

Guys, I've got a Prowhirl 73 a client site that's never worked correctly since they installed it. After a little investigation, found that the 73 was spec'd as a Saturated Steam flow xmtr, but its actually a Superheated Steam system. E+H has now had us install a Cerabar-S to be used for external correction, and a pair of their RN221 active barrier's, that'll talk HART back and forth at the module, and then send the corrected in to the PLC.

If I have a HART card installed in the PLC already, why can't I do the correction in the PLC instead ? I talked to E+H about this already, and the Tech said that they didn't have the formula to do the correction, which was suspect to me.

Ideas ?

Nobody eh ?

Prowhirl 73 is a vortex flow meter?

Cerabar-S is a _____ ? I suspect it's an absolute pressure transmitter.

It sounds like the Cerabar measures absolute pressure and feeds it to the vortex meter?

The vortex meter probably measures the medium temperature already.

With the pressure data and the existing temperature and volumetric flow rate data, the vortex meter calculates corrected mass flow for superheat conditions?

HART provides up to 4 variables that are supposed to be able to be read without a DD file, by any HART master, which your a PLC HART card presumably is.

If you can get the absolute pressure, temperature and volumetric flow rate data into the PLC, then presumably you can calculate mass flow if you have the equations and math functionality. The data can be analog or, if the PLC reads the secondary, 3rd and 4th variables, which the HART card probably does, then you can get the data via HART.

Yes, Cerabar-S is the PIT. Like I said, after asking E+H why I need them, and if I could do the correction in the PLC, they couldn't really answer me. Everyone I've talked to agrees that unless theres something the manufacturer is not telling me, I should be able to omit the 221's from the design and simplify things.

What do the 221's do?

Can you 'see' all the 4 HART variables on the vortex meter with the HART card?

According to the documentation, they are an active barrier, but also allow for communication between the two devices if you had a stand alone process or no PLC installed.

What do the 221's do?

Click to expand...

They don't look like they do any kind of calculation to me, they are just isolation.

http://www.za.endress.com/#product/RN221N

https://portal.endress.com/wa001/dla/50000000779/000/01/TI073ren.pdf

Why not let the vortex meter do the calculation and just feed the PLC the corrected mass flow value?

Not on that page, but they sent me an application cut-sheet that has me wiring the devices together at the Hart connector, and setting both devices for 'Burst-Mode', effectively putting both devices on the same loop. I'm using the common positive method.

I just don't think I need them, if I could get the calculation for correction.. This would have beem much less problematic if the correct instruments would have been ordered.

Dan, it can't. Its a Superheated steam system, and its a Saturated Steam flow XMTR. Incorrectly spec'd, customer doesn't want to send them back for whatever reason. I'm just the integrator. This was E+H's answer, the 221's and the new PIT.

OK. I assumed that a temp/pressure shift from the saturated steam table correlation between temp and pressure would indicate a superheat condition and trigger a superheat calc. Apparently, it does not in that model.