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I intend to select diaphragm seal for pressure transmitter and i have found that there is special seal type called pancake type diaphragm seal. Now I am interested to know about it and it's application and discrepancies with other diaphragm seals.

also our pressure transmitter located on pipe. and i dont know whether it is practical to use pancake diaphragm seal or not?

Hello Sir,
I would not really call a Pancake seal "special". This is a standard seal offering from Emerson/Rosemount. This may or may not be a good fit for your application depending on connection size/type etc...but if the PFW type seal is not a good fit, they will have others that will be good fit for your application. The PFW or "pancake" seal gets mounted between the process flange and a blind flange. It can be purchased with or without the blind flange. You may also choose to have an integrated flush port(s) in the seal as well.

Hope this helps!

Cheers :)

thanks for your reply. it was usefull, but would you explain what do you mean by PFW?

Sure....PFW is the model code for this type of seal from Rosemount/Emerson. Hope this helps!

Cheers :)

You do know the rule for diaphragm seals:
Don't use 'em unless they solve more problems than they create.

By pancake seal, I assume you mean a seal with a 'radial' capillary coming out the side, rather than an 'axial' capillary coming out of the center of the seal housing..

Why do you need the seal?

Do you have means to mount a pancake seal? Existing flanges?

I know one plant where they love the pancake seal with its radial capillary because it eliminates the failures due to using the extended horizontal capillary as a 'step' when the seal is mounted vertically.

Carl

Sure I know the applications, the process is corrosive in our plant. Actually these PTs were located on the fired heater inlet and its pilot. The plant is new so with no existing flanges.

As the application engineering department for a manufacturer of pressure transmitters we ALWAYS try to eliminate using a remote seal. A remote seal does two things for you as my customer: It INCREASES the cost and DECREASES the performance and neither of these situations should you like.

My first question is "Why do you want a remote seal??" Do you have particulate or process material that will clog or solidify in the pressure tap into the side of the pipe?

Let's talk about the application
1-You said you had a pipe with the pressure transmitter mounted on it. You also correctly questioned whether you could mount a pancake seal or really any type of flanged seal on a pipe. That is very difficult to do and I would not recommend using any type of flanged seal pancake or otherwise.

We need a bit more detail about your problem to fully answer your question. You may contact me by email--louis. dinapoli @ siemens. com