Calculate Flow Rate From Pressure

Flow Rate Equation:

\[ Q = C_v \sqrt{\frac{\Delta P}{SG}} \]

Valve Coefficient (C_v):

dimensionless

Pressure Difference (ΔP):

psi

Specific Gravity (SG):

dimensionless

Flow Rate (Q):

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1. What is the Flow Rate Equation?

The flow rate equation \( Q = C_v \sqrt{\frac{\Delta P}{SG}} \) relates the flow rate through a valve to the pressure difference across it, the valve's flow coefficient, and the fluid's specific gravity. This is commonly used in fluid dynamics and engineering applications.

2. How Does the Calculator Work?

The calculator uses the flow rate equation:

\[ Q = C_v \sqrt{\frac{\Delta P}{SG}} \]

Where:

\( Q \) — Flow rate (gallons per minute, gpm)
\( C_v \) — Valve coefficient (dimensionless)
\( \Delta P \) — Pressure difference across the valve (psi)
\( SG \) — Specific gravity of the fluid (dimensionless)

Explanation: The equation shows that flow rate is proportional to the valve coefficient and the square root of the pressure difference divided by specific gravity.

3. Importance of Flow Rate Calculation

Details: Accurate flow rate calculation is crucial for system design, valve sizing, process control, and ensuring proper operation of fluid systems.

4. Using the Calculator

Tips: Enter the valve coefficient (C_v), pressure difference (ΔP) in psi, and specific gravity (SG) of the fluid. All values must be positive numbers.

5. Frequently Asked Questions (FAQ)

Q1: What is the valve coefficient (C_v)?
A: The valve coefficient is a measure of a valve's flow capacity, defined as the flow rate in gpm of water at 60°F that will produce a 1 psi pressure drop across the valve.

Q2: What is specific gravity (SG)?
A: Specific gravity is the ratio of the density of a fluid to the density of water at standard conditions (typically water at 4°C or 60°F).

Q3: What are typical C_v values?
A: C_v values vary widely depending on valve size and type, ranging from less than 1 for small valves to over 1000 for large valves.

Q4: Does this equation work for all fluids?
A: The equation works for Newtonian fluids (like water, oil, etc.) but may need adjustment for non-Newtonian fluids or compressible gases.

Q5: What if my pressure difference is very small?
A: At very small pressure differences (typically below 1 psi), other factors like laminar flow effects may become significant and this equation may be less accurate.