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Formula of Calculation

Liquid Flow Coefficient Cv Calculation

1. Variable Definitions

\(C_v\) Flow coefficient
\(Q\) Flow (gpm)
\(SG\) Liquid specific gravity (water=1.0)
\(P_1\) Inlet Pressure (psia)
\(P_2\) Outlet Pressure (psia)
\(\Delta P\) Pressure drop (P₁-P₂)

2. Basic Calculation Formula

\[ C_v = Q\sqrt{\frac{SG}{\Delta P}} \]
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Note:Applicable for incompressible liquids under non-cavitation and non-blocking conditions.

Gas Flow Coefficient Cv Calculation

1. Variable Definitions

\(C_v\) Flow coefficient
\(Q_g\) Gas Flow (SCFM)
\(SG_g\) Gas specific gravity (air=1.0)
\(P_1\) Inlet pressure (psia)
\(P_2\) Outlet pressure (psia)
\(\Delta P\) Pressure drop (\(P_1-P_2\))
\(T\) Absolute Upstream Temperature (Kelvin K= °C + 273)

2. Calculation Formulas by Operating Conditions

\[ C_v = \begin{cases} \dfrac{Q_g}{125.6} \times \sqrt{\dfrac{SG_g T}{\Delta P \times P_2}} & \text{if } P_2 > \dfrac{P_1}{2} \\[2ex] \dfrac{Q_g}{62.8 \times P_1} \times \sqrt{SG_g T} & \text{if } P_2 \leq \dfrac{P_1}{2} \end{cases} \]
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Liquid Kv Correction Calculation

1. Variable Definitions

\(K_v\) Flow coefficient
\(Q\) Liquid Flow (m³/h)
\(SG\) Liquid specific gravity
\(P_1\) Inlet pressure (psia)
\(P_2\) Outlet pressure (psia)
\(P_c\) Liquid critical pressure (bar)
\(P_v\) Vapor critical pressure (bar)
\(\Delta P\) Pressure drop (\(P_1-P_2\))
\(\Delta P_c\) Choked Pressure Drop
\(F_L\) Pressure recovery coefficient

2. Choked Pressure Drop Calculation

\[ \Delta P_c = \begin{cases} F_L^2 (P_1 - P_2) & \text{if } P_v < 0.5P_1 \\ F_L^2 \left[ P_1 - \left(0.96 - 0.28\sqrt{\dfrac{P_1}{P_c}} \right) P_v \right] & \text{if } P_v \ge 0.5P_1 \end{cases} \]
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3. Corrected Kv Calculation

\[ K_v = \begin{cases} Q\sqrt{\dfrac{SG}{\Delta P}} & \text{if } \Delta P < \Delta P_c \text{（General flow）}\\ Q\sqrt{\dfrac{SG}{\Delta P_c}} & \text{if } \Delta P \ge \Delta P_c \text{（Choked flow）} \end{cases} \]
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Conversion Relationship Between Cv and Kv

\[ C_v = 1.156K_v \]
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Note: The conversion factor 1.156 is a theoretical value derived from unit conversion relationships between US gallons and cubic meters, psi and bar.

Gas Kv Correction Calculation

1. Variable Definitions

\(K_v\) Flow coefficient
\(Q_N\) Gas Flow (Nm³/h)
\(SG_N\) Gas specific weight (kg/Nm³)
\(P_1\) Inlet Pressure (bar)
\(P_2\) Outlet Pressure (bar)
\(\Delta P\) Pressure drop (\(P_1-P_2\))
\(T\) Absolute upstream temperature (Kelvin K = °C + 273)
\(F_L\) Pressure recovery coefficient

2. Calculation Formulas by Operating Conditions

\[ K_v = \begin{cases} \dfrac{Q_N}{380} \times \sqrt{\dfrac{SG_NT}{\Delta P(P_1+P_2)}} & \text{if } \dfrac{\Delta P}{P_1} < 0.5F_L^2 \text{（General flow）}\\ \dfrac{Q_N}{330} \times \dfrac{\sqrt{SG_NT}}{P_1} \times \dfrac{1}{F_L} & \text{if } \dfrac{\Delta P}{P_1} \ge 0.5F_L^2 \text{（Choked flow）} \end{cases} \]
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Cv and Kv Conversion Relationship

\[ C_v = 1.156K_v \]
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Note: The conversion factor 1.156 is a theoretical value derived from unit conversion relationships between US gallons and cubic meters, psi and bar.

V. Cv and Kv Conversion Relationship

\[ C_v = 1.156K_v \]
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Note: The conversion factor 1.156 is a theoretical value derived from the unit conversion relationships between US gallons and cubic meters, and between psi and bar.

Data Sheets

Physical Constants of Various-Fluids
Critical Pressure of Common Liquids
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