parallel connected EPR valves question

[friocold2008]

As part of an expansion project, I had to replace the existing parallel connected epr valves in a rack system circuit with larger eprs, since the new evaporators are bigger than those originally installed.
After start up, while trying to adjust the epr valve settings to the appropiate level, I have noticed that one of the eprs gets much more colder than the other, even thought the pressure setting look the same in both.
I am curious about this difference in temperature, since I believe that the temperature of both valves should be about the same.

[lowcool]

you better run back and close the tev a bit,or go back when comp trips oil fail or is scattered around plant room

[Silhouette]

Parallel EPR's are very difficult to set up at the exact same operating pressure. There will be a tendancy for one of the valves to open sooner than the other, due to machining inaccuracies and possibly differing spring tensions, under low load conditions, it will possibly be the only valve to open! As long as the operating condition is being maintained and you have no flood back I wouldn't be too worried.

[Brian_UK]

I'm sure that you have the information but some of Sporlans documentation on EPRs may be of use/interest to you...

http://sporlan.jandrewschoen.com/prvs.shtm

[750 Valve]

If they are suction stop EPR's (like a SORIT or PM valve) just shut one off and set each one as best you can, if they are not (like ORIT or KVP style) then set as best you can - as mentioned above its very hard to get exactly the same setting on each one, I honestly wouldn't be too worried about one being colder than the other (its obviously opening a little earlier) provided they can maintain required SST at max and min load scenarios

[friocold2008]

Thank you very much for your interest and kind advice.
As you mentioned, these valves are Sporlan SORIT type valves, and yes, I´ve been reading the available Sporlan literature on these EPRs.
I have some catalogs from hvac suppliers which include the internal parts for these valves. Does anyone has had some experience in servicing these devices? I just want to make sure that the difference in temperature is due to normal conditions and not to an internal problem within the throttling mechanism.
Best regards.

[lowcool]

wondering what are the temperatures and differences

[Gary]

An EPR sets a minimum upstream pressure, thus a minimum saturation temp in the evaporator.

But the suction line back at the EPR is not at saturation temp, it is superheated.

Some suction lines are more superheated than others, especially very long suction lines.

[lowcool]

gday gary would it be harder to achieve same temps if evap superheats are different

[lowcool]

gday frio probably didnt expand enough on that question for gary,its that i have come across many a epr being reasonably cold only due to superheat being to narrow across coil or reversed and appears that refrigerant takes on another effect again after pressure change,shut the tx valve down,balance the system and then set the eprs.have you taken any temps?

[friocold2008]

Tomorrow I´ll be working on that same rack. I am going to get some actual temp and pressure readings in order to provide you with more info on my problem.
Regards

[Gary]

gday gary would it be harder to achieve same temps if evap superheats are different

No... CPR settings and TXV superheats are two separate issues.

[lowcool]

sorry gary but i thought we were talking about epr valves

[Gary]

Oops... I meant to say EPR, not CPR.

[lowcool]

if the evaporator superheat is not correct whats to stop liquid backing up before the epr outlet

[Gary]

if the evaporator superheat is not correct whats to stop liquid backing up before the epr outlet

Nothing...

[lowcool]

gday frio,if the evaporator uses a heat exchanger before tev and evap outlet this may also have split etc internally,allowing liquid to bypass evap and go straight to suction line.closing the tev down will be a quick indication if its at fault.
be good to know your epr temps as to how cold is much colder from your first post

[Gary]

As part of an expansion project, I had to replace the existing parallel connected epr valves in a rack system circuit with larger eprs, since the new evaporators are bigger than those originally installed.
After start up, while trying to adjust the epr valve settings to the appropiate level, I have noticed that one of the eprs gets much more colder than the other, even thought the pressure setting look the same in both.
I am curious about this difference in temperature, since I believe that the temperature of both valves should be about the same.

Some EPR's colder than others doesn't necessarily mean anything. There may or may not be a problem with superheat.

[lowcool]

frio are we talking two valves per evap?