hello,

i have one concern about the level transmitter on condensate drum and transmitter are A, B, C. B and C always accurate but the A always comes erratic mean showing high reading, and after refilling the water on low side impulse line its become ok.

can anyone guide me or tell me what is the actual problem with this transmitter (rosemount) DP type?

 

to address your question with any meaning, you need to furnish the detailed vessel drawings, and field verified installation details for those instruments.

 

There's nothing wrong with the transmitter, it's accurately reporting exactly what's happening - the emptying of the low leg impulse tube. That may not be what you want, but that's what the system performance is and that's what the transmitter is telling you.

The measurement system is set up with a wet leg on the low side. The premise is that the wet leg will remain filled because an accurate measurement relies on a constant hydrostatic head on the low side. Your low side is not constant level, it's a varying level.

As the condensate fill evaporates, the hydrostatic pressure decreases proportionally, with a corresponding proportional error indicating an erroneously high level.

Do you have a condensate pot installed? Is the impulse leg insulated?

 

You are really not giving much for us to work with so if the assumption I am making is wrong it is your own fault that you get inaccurate or unhelpful feedback.

I will make the assumption that you have three identical wet legs on a condensate drum. Two is working fine but the third seems to loose it’s wet leg from time to time.

Have a look at your five or three way manifold; the equalizing valve might be leaking through. If possible replace the complete manifold.
Since condensate is oil based with a sg around 0,85, to use water in the wet leg is the right way to go. David is suggesting a catch pot which will be ideal to do but if that cannot be done make use of a simple T-Piece and install that as well as an isolation valve in the LP leg just before it is connected to the vessel. It will make life easier to just unscrew the plug on this T-piece to fill your LP leg or to check it is still full. It serves the same purpose as a catch pot, only smaller and easier to install.

Hope this helps but if not send us more details of your installations and also what you have done so far and what the problem is.