The expansion valve holds back the refrigerant and maintains the high pressure from the condenser. Inside the expansion valve, a small orifice enables a limited degree of refrigerant to carry on to circulation. Because it flows by means of this restriction it reaches the lower stress facet of your valve. https://www.penmann.co.uk/penmann-delivers-permanent-glycol-chiller-solution-for-ambrosia-creamery-in-lifton/