Pressure Transmitter- Temperature Rating

[akh]

I am installing Rosemount 3051S Pressure Transmitter on hot air duct. The air temperature is 400 deg C. I am using 3/8" impulse SS tubing. Pressure Transmitter temp rating is around 100 deg C. I know installing certain length of SS tubing will reduce temp. But how much, I do'nt know. Can anyone help me on this? Some book/white paper reference is appreciated.

 

[danw2]

See this discussion to 'shop' for an answer for temperature drops on dead headed impulse lines:

http://www.control.com/thread/1240831095#1240921577

If you find the white paper, please let me know.

 

[JLSeagull]

A magic solution that seems to last forever could fail if a technician permits the process to flow through the tubing at the manifold valve during service. ;-)

I'm just sayin' ...

 

[danw2]

Hey, that's just the another form of 'manifold cooking' where the more common version is when food is wrapped in aluminum foil and cooked on a car engine's manifold!

The process world's 'manifold cooking' has better heat control through careful adjustment of the equalizing valve :')

Dan

 

[akh]

Thanks Danw2, I checked control.com thread. It is helpful. However, i am still working on my end and also talked to emerson rep., every person I discussed the answer is "Rule of Thumb" 1 foot of tubing drops 100 deg C.

Any tip or link you find let me know. Thanks

 

[JimCasey]

Side note: Slope the tubing downward from the instrument back to the process. Any condensate that forms will then run back to the process and not build up in the instrument line.

If condensate builds up in the line the other way, it will at the minimum introduce a zero error equivalent to the height of the condensate column in the sensing line. If it's pure water, it might freeze in there, and is it has dissolved substances, it could solidify -either way you lose the true reading and get a false reading. Could lead to a hazardous condition.

 

[glowing]

i would contact rosemount. in similar applications i have used necked / standoff manifolds. I was shocked at how much research has been put into temperature rating and management in the past few years when i attended a seminar a few months back.

I have actually installed rosemount transmitters with direct mount kits directly above surface areas that contain well over 400C process. It is a matter of getting the right sized standoff.