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aygul
24-08-2003, 09:25 AM
Hello everybody,

In our cooling units we are using 20 tons electronic expansion valve, but i want to use 30tons expansion valve instead of 20 tons in our system ( reason stock problem) . We are using these units not only for summer application but also for proses cooling (winter and summer).

What kind of problems does it cause if we use "oversizing step motor electronic expansion valves (EXVs)" ?

Thanks for your comments…

Regards

Jasper
24-08-2003, 10:45 AM
Aygul

I would imagine that restricting refrigerant flow will be a major problem due to the larger oriface size in the 30ton eev

cooltrain
24-08-2003, 11:19 AM
Hi Aygul,

EEV or EXV could be oversized to a certain extent but unfortunately I don't know the figures.

Malfunctions on oversize EEV's could be some delayed responses.

I mean wider gate takes more time to close.

However, if the controller is program properly with regards to the superheat, minimun start-up opening, proportional band and integral time then no much hassle to expect.

More importantly is to calibrate the EEV as per manufacturers instructions and always use a compatible controller (same manufacturer matching).

aygul
24-08-2003, 11:33 AM
In our system we are controling exv acording to the superheat . According to that i thought we can use 30tons exv instead of 20tons.

Could you please tell me Is it correct or not?
Regards

Prof Sporlan
24-08-2003, 03:13 PM
aygul, in general, one should not run into any problems using a 30 ton step motor EEV on a 20 ton load. This assumes your controller is effective in controlling the EEV for the type of equipment it is applied.

shooter
20-11-2003, 01:00 PM
it should be no problem at all, just be sure it is closed when needed. the steps will have to be a little faster as flooding could be a problem, never saw it however as control even in freezing is good. If your car is able to drive 30 miles it also can run 20 miles without problems you will see it will hunt a little more. but hey it is driving and or cooling.