Oil Differential Check Valve SPORLAN OCV

[georgedvf]

Hello.
I've been reading about the use of OIL DIFFERENTIAL CHECK VALVE from Sporlan model OCV. The manual says that it is for use in Industrial systems working Low Pressures to assure correct oil flow from reservoir.

But I didn't understand very well how it works and when to use it and why.

Right now I'm working on a R-404A - 17psig suction pressure Parallel Compressor Rack and there's no Oil Differential Valve on it, should I have one of this on the Oil control system?

Does anyone know how it works and why/when do you have to use it?

Thank you.

[Tesla]

Hi georgedvf
This little valve is usually on the top of the oil resivour, which collects oil from a high side float. The valve helps to maintain pressure in the resivour to something like for an old R22 system with two Vilter open drive compressors 20 psi above suction pressure. The valve out let is connected to the suction line where excees pressure is vented. This helps remove some remaining refrigerant in the oil resivour and allows the oil to flow into a common oil return line which feeds to another oil float on the side of each compressor with a 20 psi differential. Other wise the returning oil could increase the crank case pressure too much effecting compressor lubrication and some unloaders operation.
There are many ways to return oil to the compressor so the best way is to do a line drawing of the oil return system to understand better how it works. You could call sporlin - they have helped me to understand in the past. It also is dependant on the type of refrigerant as to weather the oil floats on refrigerant or the refrigerant floats on the oil.

[georgedvf]

Thanks Tesla.
I have a coalescent Temprite 930R separator-reservoir built in model at discharge of compressors, there's no valve at the top, at bottom there's the common oil return line through a OF-303 filter and then to the compressors, wich have Trax-Oil level control each.

Discharge is about 250psig and suction 17psig on R-404A.

Do you think I can have troubles on crankcase pressures on this system as it is? Shoul I get a OCV valve? How can you tell the oil returning pressure to the crankcase?

[Tesla]

Depppends on the type and size of your compressors, smaller systems use much simpler control with a seperator which is also the resivoir and a compressor oil level control. I have only seen these OCV valves on industrial sized systems. I should imagine the system should have been designed correctly. If you have oil level or return problems this could help or if you have compressor problems. Do you have any system problems?

[georgedvf]

I have a broken compressor, you can see the "Compressor Liquid Return R-404A washing Oil " post, but I'm trying to figure why protections didn't actuate.

We found the low pressure switch didn't cut off when defrost, but I'm not sure what happened then, one theory is that there was no oil return, but I have the Temprite coalescent separator wich is supposed to separate 98% and return it to the compressors, also why the oil level control didn't shut off the compressor.
Another theory is that with no refrigerant going through the compressor there's no cooling, so the oil temperature goes up and loses the viscocity, but we did an oil test and found it clean.

[joe-ice]

you have a normal high pressure oil system,is very common no need for a check valve,however i have come across problems with this type of system overfilling certain types of splash lubricated compressors .

[D.D.KORANNE]

In the absesnce of the ocv , the oil temp is about 1ok lower than dis line temp . In low temp applications example sst at minus 20 deg c , the dis of temp is high and as a result oil temp inti comp crank-case could reach application limits which could result in serious lubrication issues for comp.

Ocv could mitigate oil temp issue........and as mentioned above in replies it maintains about 10 to 20 psi pressure higher sothat oil could enter crank-case ...

[georgedvf]

Does electronic control TRAX-OIL makes any difference on this???

[sterl]

What you have is the high pressure version of the Trax Oil system.

What you don't have is the Oil Reservoir which represents the Low Pressure version of this system....On the low pressure version you definitely need something to keep the oil reservoir pressure above the crankcase pressure. Note that any refrigerant that was accompanying the oil from the separator is going to tend to percolate to the suction line with the reservoir plus OCV arrangement. But on standby that same oil reservoir can receive liquid refrigerant from a cold oil separator and duly pass it on to the suction header on the rack. And if the last operating compressor pumps down deep: the oil reservoir is the lowest pressure point on the high side of the system; it will tend to make the separator pressure drop pretty quickly when the machine shuts off. There would need to be a solenoid valve on oil line from DOS to reservoir to prevent standby migration of refrigerant or depending on the nature of the rest of the head pressure control arrangement you could deliver refrigerant to the compressor crankcases during standby....

The indicator would be a frothy crankcase on the first machine to re-start after the standby.