Flow of steam service

[student00]

Working on a problem and looking for feedback. I have a DP element on a steam application, there is concern the measurement is not accurate. The install has the impulse lines at a 45deg to a condy pots, then a wet legs to the transmitter, fairly standard. Thermal imaging shows the High side pot to be 105C down to 60C and the low side steady at 30C.

Any thoughts as to why the differential in temp? Is this the cause for the error?

 

[roydm]

Perhaps the process connections are different allowing more circulation in the hot side, try pinching down on the root valve on that side to see if it changes.
What is your primary element orifice or pitot tube?
Roy

 

[Standingback]

If there is a 3 valve manifold fitted to the transmitter then the increase in temperature could be due to the equaliser valve not seating correctly.

I suggest that you isolate the transmitter at the 3 valve manifold and attempt to ensure there is no flow through the impulse lines.

Roy may be onto something when he suggests there may be a greater circulation one one side. So check that that the tappings on the DP element provide a steam/condensate interface on the same horizontal plane.

I trust this helps,
Mlv

http://www.coulton.com

 

[JLSeagull]

I don't do much steam these days. I calibrated transmitters with condensate pots several decades ago (early 1970's) but have not done a new installation using pots since then.

Are the impulse lines hard pipe or tubing?
Are the pots filled with antifreeze?
Are both filled equally and with the same fill fluid?
Could water boiled away on one leaving more antifreeze in one than the other?
Is the installation suitable for replacing the condensate pots with siphons?
...

 

[JLSeagull]

BTW I typically used five-valve manifolds for steam to accommodate blowdown.

 

[JimCasey]

More turbulence at the HP sensing connection keeping more live steam in the cond pot?

Uneven slopes of the sensing lines so that the HP pot drains more freely?

Could be something as simple as the HP Pot root valve is mounted with a horizontal stem so the steam propogates thru it freely, but the LP root valve mounted vertically has effectively a P-trap in it. That would probably also intriduce several inches of zero error in the signal.