The expansion valve holds back the refrigerant and maintains the substantial tension from the condenser. Within the growth valve, a little orifice will allow a restricted level of refrigerant to continue to stream. Mainly because it flows through this restriction it reaches the very low pressure side in the valve. https://www.penmann.co.uk/penmann-delivers-permanent-glycol-chiller-solution-for-ambrosia-creamery-in-lifton/