Cooler SetPoint

[jaysephus]

personal stuff sorry

[US Iceman]

Where does the liquid come from?

[RANGER1]

The liquid supply line pressure has to higher than suction obviously .

But if you have a back pressure regulator in suction line , thats when you have to be concerned with liquid pump pressure always being above its pressure set point so you get flow .

Ideally it could be piped as a dual duty room for plantroom efficiency .

Is there going to be anything running at freezer duty ?
If not do you have any dual duty compressors ?
What type of liquid makeup do you have on freezer accumulator ie high or low pressure .

[jaysephus]

personal stuff sorry

[RANGER1]

jaysephus , do you have a swing compressor ?

( A compressor that can run high or low stage with necassary changeover valves on suction and discharge ) .

If you do you can common up suctions low and hi temp . High levels etc would still have to protect compressors though .

If you change any transducer with different range PLC programe will have to have a scaling mod anyway .

Note . Question asked about high pressure liquid used to makeup low + high accumulators .
Some plants use makeup to LT accumulator with liquid from HT accumulator , so pressure difference would then be necassary . This would prevent commoning up suctions .

[mad fridgie]

If you are going to use these pressures at the evap, you will end up sucking the moisture out of the air and the product, your fresh veg will end up looking like dried veg. So you will need to rehydrate the air, or introduce a back pressure regulator.
By telling the money manager that this will F**K his product, he should give you the cash to upgrade, well at least a couple of valves and a hour or so for you PLC guy.
As ranger says your PLC guy can change the range on your transducer, you loose a little acurracy, but this is not going to matter on a system like this.

[jaysephus]

personal stuff sorry

[RANGER1]

If you change transducer with one of a different scale the PLC needs to be rescaled as well as limits on your setpoints .
Crepaco sound good to do what you want . You could even inhibit its loading on a few banks to limit its capacity .
All coolstores etc are the same these days , as some knob has a university degree in accounting or something else we never heard of .
They then attempt to pretend they know whats going on .

You only want to do the right thing and someone else will get credit for it .
Then the safety officer says you cant do it that way its to dangerous .
They keep writing up new procedures but won't spend any money on keeping system safe , as thats an overhead like you and me .

P.S I woke up grumpy .... again .
We have to follw suit with eveything from the US as thats where all the insurance companies come from .

Take a week off , turn your phone off and relax .
The world will keep turning .

[jaysephus]

sorry people i deleted all my posts

[RANGER1]

I know nothing about Crepaco but with the pressures your running you may not need it .

Other brands like Vilter don't have water cooling on low side heads , only high side heads .

If you go this way it might be worth a try to run it without water and monitor discharge temps , see what happens .

[charlie n]

If these are belt driven compressors, you would get a moore steady performance by changing the motor pulley and slowing them down. Also, a pressure switch in line with the 50% solenoid would unload the machine when suction pressure goes down. This will also smooth out the operation a little. Two stage compressors shouldn't run with suction pressure higher than 25 psig so you'r going to have a high TD at the cooler evaporators. When the room is full of product, the temoperature swings won't be too bad as the plant cycles on and off.

[jaysephus]

sorry but i want to delete all my posts

[CHIEF DELPAC]

JAY. For about 3 months of the year we use 4 blast freezers as cool rooms. The blast freezer /chill rooms are kept between 0 & 2 C. by a 4B MYCOM comp. We changed the suction piping and added a back pressure regulating valve. WE run the evaporaters which are liq. overfeed with only one fan on. The hand expansion valves are cut back to one quarter of a turn.The evaps. have thermostats which are set to keep the temp. above freezing by opening and closing the main liquid sol. valve to each evap.The rooms capacity for freezing is around 25000 pounds. The comp. runs about 50% of the time. The comp. starts at 35 psi and stops at 15 psi. The back press. reg. is set to 50 psi. C.D.

[jaysephus]

sorry but i want to delete all my posts