Hello all,

We have bought some Remote Seal DP and Pressure Transmitter from Honeywell. They have provided some calibration ring sort of thing to calibrate the transmitter. Can anybody tell me how to calibrate the Transmitters with the help of these Calibration Rings and what's the use of these calibration Rings. Please reply as it is urgent for me.....

Regards
Vikas Dhiman

 

I'm not sure why they're called calibration rings, but I'm guessing that they're the same things we call flushing rings.

Flushing rings are used for flange-mounted or sandwich style remote seals when the process conditions cause the medium to form deposits that can, literally, block the diaphragm. The flushing ring gets clamped between the process flange and the remote seal. The threaded ports in the sides of the flushing ring provide access for flushing solution to attempt to flush away the junk from the diaphragm.

For calibration, I suppose one could connect a pressure source to the ring's threaded port but it would have to be on a calibration test jig, because what pressure source could fill the volume of a tank or pipe? We don't use rings on remote seals for 'calibration', we use them for flushing out the junk that blocks the diaphragm.

A graphic showing a flushing ring installation is here:
http://tinypic.com/r/282uqe/6

With regards to 'calibration', meaning, applying a pressure of trusted, known source and making the transmitter match the source.

There's only two critical 'smart' transmitters of about 60 at my plant on which we check calibration twice a year, and neither of those have drifted enough in 4-5 years to bother with. Commissioning for DP's is configuration, not calibration. Configuration is just the standard HART stuff - tag, units, LRV, URV ranges, zero correction, maybe elevation or suppression for level, square root for flow, depending on what function your DP is destined for.

My advice is, don't mess with the actual calibration on a new transmitter. What the factories do nowadays is far better than what I or my colleagues in similar plants can do for 'applied pressure' calibration. I'm old enough to have done DP cals with dead weights and iterative zero and span pot adjustments. Good riddance to that and point ignition on automobiles.

 

Many remote seals have a flushing connection to clean or to purge the seal, which can be used as a calibration connection. In other cases, a calibration ring (sometimes known as a Dutchman) is used, which is essentially a ring with a pressure connection that is mounted between the remote seal and the process root valve. See Figure 9 in the below URL.

The calibration ring is commonly used for online calibration or troubleshooting by blocking the process root valves and then venting the ring connection(s) to a safe place. A pressure calibration source is then connected to one of the calibration rings (normally the high side) and the appropriate calibration pressures applied.

http://www.honeywell.de/imc/fi/dokument/dokument/34-ST-03-64.pdf

William (Bill) L. Mostia, Jr. PE
Sr. Consultant
SIS-Tech Solutions
wlmostia [at] msn.com

All information is provided on a caveat emptor basis.

 

Thanks for your reply sir,

I got your point little bit. But I m still confused because the Honeywell People calls it the calibration rings. Although they have mentioned it in their catalog. Below is the link for your reference on page no 3 and Figure 9.

http://hpsweb.honeywell.com/NR/rdonlyres/7F61E700-069C-4100-8003-409E0E173DC9/78186/34ST0364_En.pdf

Actually this doesn't mean to be for any type of calibration than just applying pressure and flushing.

 

This ring is used for calibration purpose. Isolate the process connection by DBB or SBB valve and in that ring 1/2 inch tapping provided to connect the pressure calibrator for calibration.