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thermal expansion valve p&id symbol?

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Spindel

Electrical
Joined
May 28, 2017
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4_2.png


I've scrached my head for several hours trying to draw this valve in a P&ID drawing, this valve has external equalizer line for the diagram, and the diagram is controlled with a bulb filled with refrigerant.

psMMp83.png

hekzl0A.png
 
The line from the "thermowell" to the expansion valve / TCV actuator is usually drawn as a capillary impulse line - see standard ISA instrumentation symbology for this.
Suspect the other equalising line you speak of may be connected to port 6 on the valve ? The second diagram appears to have the field location for the other end of this equalising line as somewhere just downstream of the TCV sensing line. But this wouldnt make sense, since the temperature here is a moving variable. What does the TCV manufacturer or the system OEM have to say about this location?; and what fluid should be used for this impulse line( most likely the same refrigerant, so capillary line for PID symbology also).
In the plant I used to work in, where we had a similar expansion TCV, there was no equalising line.
 
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