The U.S. Type 1118 three-way valve is available in either 3/4 in. (19.1 mm) or 1 in. (25.4 mm) sizes for modulating control of liquids,
gases, or steam in either mixing or diverting applications. The unit features one common port and two non-common ports. When used
in a diverting application, the common port is piped as the valve inlet with flow proportionally controlled through the two outlet ports. When used in a mixing application, the common port is piped as the outlet with incoming fluid entering the two non-common ports. In this application, the inlet pressure to the two inlets should be the same. Each inner valve within the unit is connected by a common stem and is stroked simultaneously by the actuator. This action causes one orifice to open as the other is closing. The Cv of each inner valve can be the same or of different value, depending on the requirements of the application.
The Type 1118 three-way valve is used in mixing applications such as temperature control. By varying the position of the inner valve,
the percentage of fluid passing through each port can be controlled as it exits the common port. The same concept can be applied to the blending of various chemicals, dyes, additives, and other fluids or gases that must be proportionally mixed. The Type 1118 valve is also well suited to diverting applications such as flow or pressure control in hydraulic systems. In a hydraulic system, the fluid enters the common port of the valve with one of the non-common ports controlling the flow to a cylinder or a vessel. The unused fluid is re-circulated back to the sump through the other non-common port.