Replacement fo CO2 Bulk Tank refrigeration unit

[Josip]

Hi, NH3LVR

If I understand you are thinking of running relief valves back to another part of the system.
This used to be common. I inventoried relief valves in a plant a couple of weeks ago and found some that way.
Vilter piston machines do this internally.
The problem you face is that the relief valve opening pressure becomes the difference between the pressure you are trying to relieve and where you are relieving to. In other words, if you have a relief valve set at 250lbs (17.2 BAR) discharging into a low pressure vessel with a 150lbs (10.3 BAR)relief the worst case conditions would mean a valve opening At 400lbs (27.6BAR).
These would be extreme conditions, such as a fire, but this might be when you need them most.
I also believe this might make the other reliefs undersize in the plant.

About Vilter I do not know, seems good construction but I know some other piston compressors having similar system like protection against liquid stroke.

I was thinking to relief high (condensing) pressure to low pressure vessel working at -20C/-30C/-45C even -10C and then maybe from that vessel relief valve to atmosphere.

Best regards, Josip

[NH3LVR]

About Vilter I do not know, seems good construction but I know some other piston compressors having similar system like protection against liquid stroke.

I was thinking to relief high (condensing) pressure to low pressure vessel working at -20C/-30C/-45C even -10C and then maybe from that vessel relief valve to atmosphere.

Josip:
I apologize as I believe I was unclear.
I only mentioned Vilter as they are a example of internally relieving pressure that is considered acceptable. The function in the Vilter is too prevent high pressure in case the machine is started with the discharge valve closed. It doubt it would be of much use in a liquid slugging situation.
My comments were directed to your post as I understand it.
Again my apologies for being unclear.

[Andy]

Hi
both Sabroe and Grasso recips have this relief fitted

If you are fitting PRV's to vent back to suction they have to be outlet independant, uneffected by the pressure at the outlet side, most common PRV's are not

Kind Regards Andy

[NH3LVR]

If you are fitting PRV's to vent back to suction they have to be outlet independent, unaffected by the pressure at the outlet side, most common PRV's are not

Andy;
Do you have a example of a PRV that is not not outlet dependant? I have never seen one for refrigeration use. We have a job coming up soon (NH3) on which we could save a great amount of time and trouble if we could use them in a couple of places. I assume the other valves would have to be increased in size to accommodate them?

[Andy]

Hi NH3LVR

Herl make some (now owned by Parker) Danfoss has a range, using a pilot and main valve assembly.
I will take a look at the Danfoss site and see if I can get a link.

Kind Regards Andy

[Andy]

Hi NH3LVR

Please use the following linkhttp://www.danfoss.com/Products/Cate...972d837cf1a%7d

Some link

POV valve is the one

Kind Regards Andy