Expansion valve testing

[archibaldtuttle]

OK, so I got the new 7.5 ton replacements on the way for the divinely inspired system trouble I spoke of earlier.

I should be able to readily determine whether the expansion valve is blocked, one suspicion I had on one circuit (btw it is thermostatic with a capillary running to a sensor affixed to the suction line at the exit from the evaporator to adjust superheat) by blowing a little nitrogen through the high side after I remove the old drier. But I'm wondering if there is a procedure to test the general operation of the valve. I suppose I could apply some ice to the probe and see if the same nitrogen delivery pressure gets a different result, but just wondering if there is any simple test, and/or if I should just replace the things since they are 15 years old.

Thanks,

[I'm] Brian [and so's me wife]

[BESC5240]

Hi,
there is a simple way to see if the charge is still in the thermostatic element. If you have your valve in your hand (so no longer build in the system) you should be able to blow through it. This is because the pressure is at 0 bar (gauge pressure) and the bulb temperature is at ambient temperature : this means big superheat ... the valve should be fully open.
If you can not blow though it:
- the charge is gone (leaky capillary ?...) or,
- if it's a MOP (limited) charge, it could be the charge has migrated from the buld to the thermostatic head due to a temperature difference (during standstill); in this case you should heat up the thermostatic head of the valve slightly (no direct flame !!!, but hot water or air dryer ...) to insure the charge migrates back to the bulb.

[chemi-cool]

I fully agree with BESC5240 [how on earth do you pronounce your nick in Belgian??]

This is the oldest and best way.

On this page, in one of the brochures, there is another expanation.
http://www.parker.com/portal/site/PA...vision#results

[Peter_1]

Chemi, you can say Bescie and 5240 is his pincode for his bankaccount.
Bescie.... blowing through a TEV, all that moisture

Had ik nog nooit aan gedacht en een goeie tip.
Translated: can you test it also with sucking on it? ....

[chemi-cool]

Sucking TEV?

No..........all the oil and gas residues inside.....

I will pass...

[icecube51]

when you mount a new valve,should you not mount a schreader point just after the valve,so if needed there can be manifolds mounted there.???


Ice

[Pooh]

Icecube
even more Shraeder valves fitted think of the leaks!!

Ian

[icecube51]

a good welder have no leaks
and its not the leaks where talking about, its the actual testing of valves.

Ice