Manual Expansion Valves

These are hand operated needle valves. The amount of refrigerant that passes through the valve orifice depends on the valve opening that is manually adjustable. Its biggest advantage is its simplicity and low price and its biggest disadvantage is its inflexibility. It is used in large systems, as a bypass valve, in parallel to the automatic valves, to ensure the functioning of the system in case of failure, or during repairs. Some flooded evaporator control systems also use manual valves to charge the system and to control the liquid level. In this case, there is a float switch and a solenoid valve as the preferred command control.