Valve flow rate for a liquid is the volumetric quantity of liquid that passes through a valve in a given amount of time under specified operating conditions. It describes the liquid flow capacity of the valve. The actual flow rate through a valve depends on the pressure difference across the valve, the valve opening position, the liquid properties, and the valve's internal geometry. When a valve is opened, it creates a flow path that allows liquid to move from a region of higher pressure to a region of lower pressure. The greater the pressure drop across the valve, the greater the potential flow rate, provided other system limitations do not restrict the flow.
Valve Flow Rate for Liquid Formulas |
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\( Q = C_v \cdot \sqrt{ \dfrac{ \Delta p}{SG } }\) (US units) \( Q = K_v \cdot \sqrt{ \dfrac{ \Delta p}{SG } }\) (SI units) |
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| Symbol | English | Metric |
| \( Q \) = Valve Flow Rate | \(ft^3\;/\;sec\) | \(m^3\;/\;s\) |
| \( C_v \) = Valve Flow Coefficient (US units) | \( dimensionless \) | \( dimensionless \) |
| \( K_v \) = Valve Flow Coefficient (SI units) | \( dimensionless \) | \( dimensionless \) |
| \( \Delta P \) = Valve Pressure Differential | \(lbf\;/\;in^2\) | \(Pa\) |
| \( SG \) = Liquid Specific Gravity (Water at 60°F = 1.0000) | \( dimensionless \) | \( dimensionless \) |
