RTD- sheath construction and specification details information needed.

[arun1990]

hi,
i want to know all practical aspects about sheath of RTD.
1.how sheath is attached to RTDs.? what are the various ways? welded or joined or any other means.?
2. what is meant by seamless sheath in RTDs. ? what is the opposite of that.? RTD with seam?
3. how is sheath attached to the tip, to the body of RTD wire , to the connection head, and to termination.?

4. give details about how to install RTDs? when we remove RTDs , which part/parts are removed.??

5. and what is connection head, how it is attached to RTD.?

thanks a lot all of u in advance..!!

[carl_e]

Given the way an RTD works - a constant DC current is generated by the analog input and pumped through the resistance of the RTD to develop a voltage drop which the AI 'sees' and interprets as a temperature - you'd better hope that the construction of an RTD isolates the RTD element from the sheath, otherwise ground loops will develop and the ground loop current running through the RTD element will give false IR drops which in turn will give false temperature values.

An RTD element is typically suspended, insulated and electrically isolated from the sheath by mineral insulation, typically MgO.

The RTD element's wires exit the sheath at the "transition" and various manufacturers do transitions in various methods.

For answers to your other questions, Google is your friend.

[arun1990]

Given the way an RTD works - a constant DC current is generated by the analog input and pumped through the resistance of the RTD to develop a voltage drop which the AI 'sees' and interprets as a temperature - you'd better hope that the construction of an RTD isolates the RTD element from the sheath, otherwise ground loops will develop and the ground loop current running through the RTD element will give false IR drops which in turn will give false temperature values.

An RTD element is typically suspended, insulated and electrically isolated from the sheath by mineral insulation, typically MgO.

The RTD element's wires exit the sheath at the "transition" and various manufacturers do transitions in various methods.

For answers to your other questions, Google is your friend.

thank you..!! can you please tell me how exactly the RTD element is connected to the sheath.? you said it does not touch the sheath. then how is it attached,?
and also i want t know how th RTD element, sheath, thermowell and the process pipe are all connected to each other.? i mean by welding/flange or any other means.?
thanks..!!

[Uthiel]

I love that we do this question:

It seems unimportant but there are many aspects to consider, WIKA is an expert in performing mechanical sheaths for RTD's, both standard jobs to work cyclic fatigue in aggressive media, both corrosion and abrasion as speeds high fluid derived from a medium nearby stirring. Down here I leave the relevant links. But there are alternative designs and to stop a train. If you need more information you should be more specific in the application. (Application type, or nature of the fluid medium, such loads shall be subject to, temperature ranges ...).

Sheaths

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RTD's

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Good Luck...