control group setpoints

[stanthonycold]

Hey Guys,

Sabroe 125 hp screw setpoints: control is set at 4"hg with cut-in setpoint of 0.0 psig ...is this correct ?

[NoNickName]

for what refrigerant, appliance and application?

[stanthonycold]

for what refrigerant, appliance and application?

Hey,

R17,Cold Storage for frozen fish/shrimp,3 evaps

[Grizzly]

Hey,

R17,Cold Storage for frozen fish/shrimp,3 evaps

Surely you mean R717 (Ammonia )
In which case you are running way to low.
Running in a vacuum can cause all sort of issues.
Grizzly

[stanthonycold]

Surely you mean R717 (Ammonia )
In which case you are running way to low.
Running in a vacuum can cause all sort of issues.
Grizzly

Yea sorry we do use ammonia.im new at this job but im pretty sure that we need to run a vacuum..Why would you not need a vacuum .Without suction will cause problems to wouldnt it ???We dont have a air curtain and 1 evap is directly above the door going into the cold storage.when the door opens up and lot of cold air rushes out causes fog in the loading bay ands water on floors.Im thinking we are wasting energy.

[NoNickName]

Hey Guys,

Sabroe 125 hp screw setpoints: control is set at 4"hg with cut-in setpoint of 0.0 psig ...is this correct ?

No, it's not. What do you mean by 4"hg? 4 inches of mercury?

[stanthonycold]

yes 4 inches of mercury.what would be the proper setting in your mind?

[NoNickName]

4inHG are 0.14 barg and correspond to -30°C evaporating temperature. Is this a low stage of a cascade system? What is the condensing temperature?

[stanthonycold]

4inHG are 0.14 barg and correspond to -30°C evaporating temperature. Is this a low stage of a cascade system? What is the condensing temperature?

suction is -34f/4.7"hg, 3 rotary screw ,6 flooded evaps

[NoNickName]

That doesn't answer my question.
What is the condensing temperature or pressure?

[stanthonycold]

That doesn't answer my question.
What is the condensing temperature or pressure?

130 psi .........

[NoNickName]

I don't think you can do it that way. 8 barg high side, 0.15 barg low side would cause a discharge temperature of 160-170°C.
I think you need to go back to the drawing board.

[stanthonycold]

I don't think you can do it that way. 8 barg high side, 0.15 barg low side would cause a discharge temperature of 160-170°C.
I think you need to go back to the drawing board.

yea sorry my bad discharge temp is 88 degrees C,discharge pressure is 120 psi,,operating pressure is 70 psi,compressor slide valve is 100% 1.3 inches of mercury,, ST is -29.0 degrees C.This compressor is not working properly.

The compressor that we have that is the same model and is working correctly has a discharge temp of 69 C ,discharge pressure 120 psi,operating pressure of 120 psi,3-4 inches mercury ST is -29.0 C.

Im new to this profession and appreciate all help and advice.

[NoNickName]

The first compressor is starving, as I see it. Maybe, somebody with more insight on ammonia can help you more.