Oil in external equalization tube

[referguy123]

Can anyone provide any experienced input on wether or not oil in an external equalization tube will affect expansion valve performance?

It seems that even if there was a bit of oil in here the pressure on the underside of the bellow would still increase or decrease with the suction pressure.

Any shared experiences are greatly appreciated.

[johndief]

I have not seen oil collect in a equalizer line to the point it would cause the valve to malfuction. I got too much soder in an equalizer line one time and the valve flooded like crazy. It is always good practice to position the valve so that the oil can drain from the equizer line back to the suction line.

[powell]

Can anyone provide any experienced input on wether or not oil in an external equalization tube will affect expansion valve performance?

It seems that even if there was a bit of oil in here the pressure on the underside of the bellow would still increase or decrease with the suction pressure.

Any shared experiences are greatly appreciated.

Interesting question. I've never ran into this or heard of any experiences about oil in the equalizer line. Being that there is not a lot of pressure drop between the outlet and inlet of the evap I would think that enough oil would create a restriction or maybe some sort of vapor lock which would effect the operation of the valve. This would cause flooding as johndief suggested.

It makes sense to mount the 1/4" line equalizer on top of the suction line to prevent oil trapping. And, if this a freezer, having a minimum of 4 defrost cycles scheduled to remove any oil trapped in the evap.

[smilies]

Even if you had 1 gallon of oil trapped in there, there is still full pressure pushing on that from the suction line.

[Bones74]

Shorten the line and get the trap out of it, The oil is probably been there since the compressor last overheated and pushed the oil out of the crankcase. Anything that messes with a TXV's operation in my mind will affect the performance. Just a thought. What do I know anyway.

[fuzzyj]

The equalizer line is there to smooth the operation of the valve, oil in the line will slow the response time thus causing erratic operation.

[powell]

The equalizer line is there to smooth the operation of the valve, oil in the line will slow the response time thus causing erratic operation.

We had a Parker TXV class today. Here is what Parker/Sporlan says which supports fuzzyj's post.

External Equalizer Use Tips
• Use external equalized valves for evaporator/distributor pressure drops over three (3) psi
• The external equalizer line can be mounted upstream or downstream of the thermal bulb for Parker valves
due to balanced port construction.
• Keep the external equalizer connection toward the top of the suction line to prevent oil draining into the valve.