1 ° Determine the low pressure value, the lowest pressure value at which the compressor should operate, ie the value that the compressor should shut down if it is reached;
2 ° Determine the pressure value for the compressor (reset), ie the pressure value that the compressor relays;
3 ° With the previous data, you must subtract the pressure value that the compressor shuts off from the pressure value that the machine turns on, this value is called Differential Pressure.
P. differential = P. on - P. off
Example: For a cold room whose suction pressure cannot be less than 10PSIG and the back pressure should not be less than 40PSIG, we will have:
PDIFERENTIAL = 40 PSIG - 10 PSIG
PDIFERENTIAL = 30 PSIG
4 ° The value that the compressor turns on in the first pressure strip, “CUT IN” on the pressure switch, is adjusted. In general, this ruler is for orientation. For a more precise adjustment, the machine pressure value must be followed. , through a manifold assembly installed as close as possible to the pressure tap location for the pressure switch.
5 ° In the second ruler, “DIFF”, the differential pressure value found must be adjusted following the machine stop at the desired pressure.
Tip: To roughly identify the value a machine stops at low pressure without having to install the manifold assembly, simply check the values set on the low pressure switch “CUT IN” and “DIFF” strips and subtract the value from the “ DIFF ”value of the“ CUT IN ”ruler.
