I am using a yokogawa flange type DP Transmitter for measuring scalding juice tank level in sugar industry.

I Observed large zero shift (about 2000mmwc) at atmospheric pressure after 30 days usage of the transmitter. I tried to zero trim it with HART Communicator, but it is not accepting that much large correction. SO i replaced it with a new transmitter but the same problem came after 20 days of usage.

The diaphragm is found in good condition. the process fluid is scalding juice; it contains some suspended begasse particles.

I am not able to find a solution to this problem. Please help me!!

 

What is the "top side" connection"? dry leg? wet leg? capillary with a diaphragm seal?

Which port is which? High side at the bottom? Low side at the bottom?

What is the process temperature of 'scalding' juice at the diaphragm of the transmitter?

Is the system under constant positive pressure or does either side of the transmitter see vacuum?

 

You need to provide some additional information as it is not clear how you zeroed the transmitter (e.g. inline or on the bench) and how it is installed in the field. The suspicion would be that it involves the lowside leg.

Some of the information of use would be:

1. Did the transmitter exhibit the zero offshoot on the bench?

2. How is your low side hooked up? To atmosphere or connected to top of tank? If connected, is a wet or dry leg used and what condition was that in?

3. Was the process high side connection itself examined? Unobstructed?

4. Was the the zero offset about the same both times?

William (Bill) L. Mostia, Jr. PE
Fellow
SIS-TECH Solutions, LP
Any information is provided on Caveat Emptor basis.

 

Dear Ravindra,

Have you checked zero of the transmitter before taking it in line coz? if we install remote seal transmitters in such a application where LP and HP side are at different elevation, there is always some DP coz of difference in elevation. That you need to compensate either by zeroing the transmitter or by zero elevation. Say if in isolated case DP is 200 mm and your range is 2000 mm you have to fill the range as 200 mm to 2200 mm. If you have done this, then check if the transmitter is suitable for that particular temperature application. My advice is to never go for zeroing in for the transmitter, rather use zero elevation/depression method. I would prefer to change the transmitter rather than performing the zero.