CONTROL VALVE APPLICATIONS FLOW MIXING APPLICATION • Using 3-Way Control Valve
PURPOSE:
For combining 2 separate fluid streams typically for the purpose of improved temperature control by mixing or blending.
OPERATION:
The 3-Way Control Valve in this system is used to blend the heated water and loop return water to produce precise temperature for the hot water loop. At lower temperature sensed by the RTD, the 3-way valve will modulate to fully open the A port and close the B port. This will allow maximum heated water from the heat exchanger to flow through the valve and supply hot water to the rest of the system. As the temperature of the loop return water rises, the 3-way valve will modulate to use less of the water from the heat exchanger and more from the loop return, thereby reducing the steam load to the heat exchanger.
INSTALLATION GUIDELINES:
(see Figure 20)
• The inlet pressure of the (2) flow streams must be equal. •
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 feed water. • 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 each of 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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