• W = Steam flow, pound per hour (lb. hr)
• K = 1 + (0.0007 x F superheat)
for steam • T = Flowing air or gas temperature (F)
• P = Pressure drop (PP) at maximum flow, psi
• P =
Inlet pressure at maximum flow, psia (abs)
• P = Outlet pressure at maximum flow, psia (abs)
CONTROL VALVE SIZING – SIMPLIFIED EXAMPLE Define the system Water is pumped from one tank to another through a piping system with a total pressure drop of 150 psi. A control valve is provided in the piping loop to modulate the flow rates. Assume
the following key variables • Fluid temperature - F
• Design (maximum) flow rate - 150 gpm
• Operating flow rate - 110 gpm
• Minimum flow rate - 25 gpm
• Pipe diameter - 3 inches
• Specific gravity – 1.0
• Valve characteristic –
Globe valve, equal percentage
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