Barber Colman (Schneider Electric) VB-8303-0-5-13 Flanged 3-Way Diverting Valve Cast Iron 3" 85Cv

Description:

VB-8303 series three-way valves control hot or chilled water in heating or air conditioning systems. These valves may be piped as mixing valves with 2 inlets ("A" and "B") and one outlet ("AB") or as diverting valves with one inlet ("AB") and two outlets ("A" and "B"). They are used for two-position or proportional control applications. Valve assemblies require an electric/electronic or pneumatic actuator and valve linkage that may be purchased separately or as part of a complete factory valve assembly. These valves will also operate satisfactorily as two-way angle valves if either end (side) port is closed off. Features • Valve sizes 2-1/2" to 6". • Excellent close-off capability up to 35 psi. • Meets ANSI III seat leakage specifications. • 125 psig pressure rating per ANSI Standards (B16.1–1993) for flanged cast iron bodies. • Self-adjusting spring-loaded TFE/EPDM packing. • Expanded operating temperatures 20° to 281°F Valve Sizing and Selection Water Flow Coefficient (Cv) Sizing a valve requires selecting a flow coefficient (Cv), which is defined as the flow rate in gallons per minute (gpm) of 60°F water that will pass through the fully open valve with a 1 psi pressure drop (Δp). It is calculated according to the formulas shown in “Cv Equation for Water”. Since the flow rate through the heat exchanger is usually specified, the only variable normally available in sizing a valve is the pressure drop. The following information can be used to determine what pressure drop to use in calculating a valve Cv. Using the calculated Cv, consult Table-4 or Table-5 to select the valve body with the nearest available Cv. Two-position Two-position control valves are normally selected “line size” to keep pressure drop at a minimum. If it is desirable to reduce the valve below line size, then 10% of “available pressure” (that is, the pump pressure differential available between supply and return mains with design flow at the valve location) is normally used to select the valve. Proportional to Bypass Flow Proportional mixing valves used to bypass flow (Figure-6) are piped on the outlet side of the load to throttle the water flow through the load and therefore control heat output of the load. These valves are usually selected to take a pressure drop equal to at least 50% of the “available pressure.” As “available pressure” is often difficult to calculate, the normal procedure is to select the valve using a pressure drop at least equal to the drop in the coil or other load being controlled (except where small booster pumps are used) with a minimum recommended pressure drop of 5 psi (34 kPa). When the design temperature drop is less than 60°F (33°C) for conventional heating systems, higher pressure drops across the valve are needed for good results