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fessy
06-01-2015, 10:08 PM
Hi guys

This is my first post just starting to get involved with refrigeration plant. just after some advice.

what should the suction and discharge pressures be for a -18C deep freeze room running on R417a water cooled condenser?

fes

RANGER1
06-01-2015, 10:41 PM
fes,
Can depend on how it was designed, but with maximumwater temp in at 29 deg C I would suggest between 9 to 12 bar or 30 to 40 deg saturated discharge temperature.
Normally set at a desired pressure to cover summer conditions & pressure difference across TX valve so it performs as per design.
What do you have at the moment & how is it controlled.

Glenn Moore
06-01-2015, 11:28 PM
Hi fes
Has Ranger says discharge pressure around the 10 to 12 Bar should be OK and the suction around 0.5 Bar.
But what type of expansion valve is on the job. If its a 404A , R22, or similar the suction will be lower as I don't know any manufacturer who makes an R417A expansion valve, and therefore the valve will not calibrate with the systems refrigerant pressure/temperature, normally resulting will a low suction guage and high superheats .
If you have an electronic valve fitted it should run the suction around the 0.5 Bar mark

fessy
07-01-2015, 08:11 PM
Cheers guys

the inlet to the condenser is 25C and outlet is 36C

TX Danfoss R22 -40/+10C PS34bar

I seam to have stabled the discharge pressure at 14.5bar and suction is 0.6 bar.

is there a formula for working out pressures for suction discharges? i.e to establish the amount of refrigerant to put into a system?

Thanks in advance
Fes

RANGER1
07-01-2015, 11:44 PM
Cheers guys

the inlet to the condenser is 25C and outlet is 36C

TX Danfoss R22 -40/+10C PS34bar

I seam to have stabled the discharge pressure at 14.5bar and suction is 0.6 bar.

is there a formula for working out pressures for suction discharges? i.e to establish the amount of refrigerant to put into a system?

Thanks in advance
Fes

Maybe liquid line subcooling.
Suction pressure several degrees below water out temp.
Water in/out seems to much difference,
Have you checked it & pump/strainer.
Does the condenser have a pressure operated water control valve or something similar?