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Our annubar, which is installed in cooling water line, was broken. Line fluid is cooling water, 52" size & 2000Ton/h. I should calculate proper thickness of annubar prob.

Does anybody have the same experience?

You have an inserted hollow stick, with holes in it, in a 52" diameter pipe, flowing 2000 T/h. Did it bend flat in the direction of flow? Or did it break off? Either way, I bet you have been a victim of "water hammer." Water is incompressible, and closing a valve too quickly can send a "hammer" pressure wave down the pipe. Water hammer can be 5 to 10 times the static pressure in the pipe... and can burst pipes and damage inserted components like multi-port pitot tube flow meters and thermowells, etc.

Some of us may be old enough to remember seeing the old Johns-Manville training film on avoidance of water hammer. It certainly made a believer out
of me.

Walt Boyes
Editor in Chief
Control and Controlglobal.com
www.controlglobal.com
Mailto:wboyes@putman.net
Read my blog SoundOFF!! At www.controlglobal.com/soundoff

Can't get the flow to fit with the pipe id. The given flow seems very low. Can you check that it's correct?

Anyway you can study water hammer on YouTube:
http://www.youtube.com/watch?v=zAG45ILN7Kk

/Ulf

Hello sir. The Annubar is manufactured by Dieterich Standard, a division of Rosemount. I am an applications engineer with the company, and would like to inquire if you have spoken to anyone within Rosemount. If not and you would like to discuss the broken sensor further, please contact me at derek. ott at emerson. com

Thank you,
Derek

There could be various reason for breaking of the ANNUBAR in the process line. A detailed study is required before commenting on the reason. Consult the supplier or the manufacturer. Most of the time the failure of sensor is not due to the construction or manufacturing issue but it is related to installation or process conditions.