Pressure Transducer

[Barrie66]

Hi All,
We have a problem with a pressure transducer with a diaphragm isolater connected to an acid tank. The tank level varies from 10 - 100" (4-20mA). The problem is that the head pressure is so small that it takes a pressure change of around 20" for the diaphragm to move (jump) from convex to concave and vice versa.
This causes erroneous signals whenever the tank is emptying or filling.
I am looking for a diaphragm isolator that doesn't operate in this way, any help would be appreciated.
Barrie66

 

[AGomaa]

Hi, I would expect that you have a transducer with diaphragm seal, that there is a filling fluid between the transducer and the diaphragm. as such the diaphragm does not have this action (concave to convex).
If not then it is better to use one who have a filling sealed fluid. Advise more details (model) of your P.Tx.

 

[Barrie66]

Thank you AGomaa
We are using a Wika ECO-1 with fluid filled diaphragm seal.
What do you mean by "Have a filling sealed fluid?" I don't know this term.
Barrie66

 

[AGomaa]

The diaphragm seal I mean is a separate diaphragm seal typically used for aggressive media (acids etc.) this is not the diaphragm in the transducer.
A typical one is model 990.10. Normally you get the transducer and the diaphragm seal pre-installed and filled with seal.

Check with WIKA they should be able to identify the cause of the problem.
(Assuming that the fluid is water and transmitter is mounted at the bottom nozzle of tank):
I noticed that your working range is 0.025 to 0.249 bar your selected range is 0-1 bar that means at your 100% level you are operating at 25% of the tx range.

The transmitter range is
the 20" is =0.05 bar =5% of the tx range.

Check your installation where is the transducer mounted? It should be at the nozzle level, if below the nozzle then you will have + offset value.
I do not think that the range of this type of transducer can be changed.