View Full Version : High Pressure on relief valve

20-04-2014, 10:22 AM
Hello and good Easter to everyone!

I recently built a refrigeration unit with 3x10hp compressors which supports 6 chambers (@ -18 degrees celsius) with one evaporator each. All the chambers are supplied in parallel from the unit and each one of them is controlled by a thermostat and a solenoid valve. My problem is that every time a solenoid valve opens (which means a chamber started working), there is alot of tube vibration which results to tube leakages. For the supply line (of the evaporators) i used 18mm copper tube (that's the failing tube). Do you have any ideas on how to avoid that vibration?

install monkey
20-04-2014, 10:25 AM

20-04-2014, 07:43 PM

thank you for the quick response! :)

To be honest, i dont think this will solve the problem because the vibration doesn't come from the compressor but from the liquid inside the tube, when the solenoid valve is open and the liquid hits the relief valve. Any other possible solutions ??

install monkey
20-04-2014, 07:44 PM
any threaded holes under the valve body- then you can secure it to the frame

20-04-2014, 08:24 PM
I have already done that :) . I am thinking to change the whole supply tube from 18mm to 1/2 inch so that the volume of the liquid to be smaller when it comes to the relief valve. What do you think about that ?

install monkey
20-04-2014, 08:28 PM
do the 3 compressors have unloaders on them? with 6 evaps .each with solonoids on em how are you controlling the demand

20-04-2014, 08:46 PM
yeap, the compressors have unloaders.About the chambers, each chamber has an ON/OFF switch. When the switch is ON and if the temperature is below the thermostat set, the evaporation fans start and the solenoid valve opens. If the low pressure rises below a limit then a compressor starts (maybe some other of the three compressors already working, depanding on how many chambers are ON). In other words, thedemand is controlled by low pressure switches. (Sorry for my poor english :) )

install monkey
20-04-2014, 08:57 PM
normally if pipes are clamped using hydrazorb clips then that can hold pipes rigid without allowing for expansion/contraction, are the solonoid coils flared or brazed?

20-04-2014, 11:27 PM
Chris, do you by any chance have a picture of the set up. This may help with ideas.

21-04-2014, 06:26 PM
Put some length of vertical pipe capped at top, just before relief valve. That will make some pocket for gases which will eventually act as damping for liquid hammers.

22-04-2014, 05:39 PM
What kind of expansion valves are you using, and how far from the expansion valves are the solenoid valves?

Just a wild guess, but it sounds like the distance from the solenoids to the TEV's might be too long and once the thermostat closes the solenoid the whole pipeline is pumped dry, and once it opens again the liquid has a long way to travel before it hits the TEV, causing vibration.

some more info would be nice :)

Jeff Winsor
22-04-2014, 06:15 PM
Have in the past brazed in a 1/4 copper bypass line around main solenoid and then opened 1/4 solenoid to allow pressure across gently before opening main valve after a delay.