CONTROL VALVE APPLICATIONS FLOW DIVERTING • Using 3-Way Control Valve
PURPOSE:
For separating a single fluid stream into 2 streams for the purpose of either splitting it or diverting excess flow.
OPERATION:
The 3-Way Control Valve in this system is used to divert excess flow from the coil when demand is not required. If the coil is being used for heating air, the RTD sensor will sense the air temperature and modulate so the A port opens to direct maximum hot water through the coil to raise the air temperature. As the coil nears set temperature the valve will modulate to reduce the amount of flow to the coil. Once the air temperature is at set point, the valve will close the A port and open the B port to divert excess hot water into a bypass line. Diverting flow through the B port is for recirculation to protect pumps from overheating if demand decreases. This arrangement would be representative of both heating and cooling coils.
INSTALLATION GUIDELINES:
(see Figure 21)
• Outlet pressures must be close to equal to provide consistent pressure differential on both fluid streams when partial flows must be maintained. • For optimum operation and service life, maintain recommended minimum piping straight runs before and after the control valve. Inlet and outlet piping should be sized to maintain appropriate velocities for the feedwater. • When the valve actuator is electric, plan the installation location of the valve so that ambient conditions do not exceed the limits of the actuator. Insulation blankets may also be used for protection. • Make certain there is at least one pipeline strainer installed on the supply lines to protect the valve from pipeline scale and debris.
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www.watsonmcdaniel.com •• Pottstown PA • USA • Tel: 610-495-5131
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