Expansion Valve mushrooms

[braveheart51]

Hello Techs,

Have a refrigeration loop that cools water/methonal to help bring testing room temp to operating conditions.

We are working with 507R and have adjusted this to around 10 PSI superheat.
This EV is ahead of a DX coil with a solenoid valve in front of it.
Feeler bulb is on suction line after evap with a stepper valve after it. Inlet pressure is about 180 to 190 PSI. suction around 110-120 PSI.

Problem....the top on my expansion valve is mushrooming after a few months of operation. Just changed it out! Looking for a solution to keep the pressure from damageing the valve during off cycle or start up.

Any thoughts.....

[Six]

The power head is inflating to the point where its no longer operational ?

The power head is essentially a diaphragm with R507 trapped inside as a sensing reference.

Is the bulb insulated ? Is it exposed to excessive ambient on the off cycle ?

[isuredo]

is a balance port txv available?

[braveheart51]

Hey Guys,

This valve is in a cabinet along with compressor and the temp can reach 90+ in off cycle. Not necessary to be insulated as its opeperating temp is with 180 to 190 discharge pressure. Do have an equallizing line between suction and supply. I think this electronic stepping valve may close on the off cycle....checking into that....
I replaced this valve two months ago as it was not performing and was really mushroomed after 2 years of operation. Present is starting to mushroom.

[braveheart51]

System gave me some trouble last week, but is operating OK now with 8 degree superheat. and hold temp rock steady. I just know that I will need to replace again, and want a perminet fix this next time.

Thanks for looking....

[beenthere]

Inlet pressure is about 180 to 190 PSI. suction around 110-120 PSI?

10 PSI SH?

[beenthere]

Moved to Tech to Tech.

[braveheart51]

Hey Guys,
Just an update on the problem I had with the expansion valve being dis-formed.
Turned out this was happening on the off cycle. Stepper valve after the dx-coil was closing at times locking the refrigerant in this loop. Pressure would climb upward to 300 psi and this pushing against the diaphragm.
Fix....put a n/o solenoid over the stepper valve to prevent pressure from building.
Braveheart....