pressure transmitter capillary lines use CTFE as filling material

[navycaptain]

Normally, silocon use as filling material for capillary line, but HF service pressure, silocon can reacte with HF if there is some leak from the diagram, and it can form explosive mixture, one of my plants have occured such accident, then i checked API751, it mentioned that CTFE can be used as filling material, but i find that CTFE is an explosive material, so my quesiton is: can CTFE used as filling material? are there any other specific material can be an altenative? thank you!

Youth is not a time of life, it's a state of mind.

 

[moltenmetal]

Fluorocarbon liquids which neither burn nor "explode" (the wrong term- you mean deflagrate- none of these materials is 'explosive') are available as fill fluids. CTFE is the acronym of a polymer (Kel F being one tradename). Many fluorocarbon liquids exist with various tradenames. Fluorinert (a 3M tradename) is a fave of mine, and there are many "weights" (vapour pressure, viscosity) available.

 

[danw2]

Major transmitter vendors list their standard fill fluids. If the mfg does not want to do custom fills, most distributors will find a service shop (if not their own) to do a custom fill if need be, if something other than a standard fill fluid is needed.

ABB's standard fill fluids:

Honeywell's standard fill fluids:

Rosemount's standard fill fluids:

Wika's standard fill fluids:

Yokogawa's standard fill fluids:

Rosemount's 1199 spec (doc 00840-2100-4016) is a comprehensive spec on fill fluids.

Another consideration is 'all-welded' capillary/seal construction, which eliminates the leak path from theaded capillary/head or capillary seal connections. It does limit rebuildability of the seals though.