1. What is the Flow Rate to Psi Equation?

The pressure drop equation calculates the pressure difference (ΔP) across a valve or restriction based on flow rate (Q), flow coefficient (Cv), and fluid specific gravity (SG). This is commonly used in fluid dynamics and engineering applications.

2. How Does the Calculator Work?

The calculator uses the pressure drop equation:

Where:

• \( \Delta P \) — Pressure drop (psi)
• \( Q \) — Flow rate (gallons per minute)
• \( Cv \) — Flow coefficient (dimensionless)
• \( SG \) — Specific gravity of fluid (dimensionless)

Explanation: The equation shows that pressure drop increases with the square of flow rate and linearly with specific gravity, while being inversely proportional to the square of the flow coefficient.

3. Importance of Pressure Drop Calculation

Details: Calculating pressure drop is essential for designing piping systems, selecting appropriate valves, ensuring proper pump sizing, and maintaining efficient system operation.

4. Using the Calculator

Tips: Enter flow rate in gpm, flow coefficient (Cv) value, and specific gravity (1.0 for water). All values must be positive numbers.

5. Frequently Asked Questions (FAQ)

Q1: What is the flow coefficient (Cv)?
A: Cv is a valve's flow capacity - the number of gallons per minute of water that will flow through the valve with a 1 psi pressure drop.

Q2: What's typical Cv value range?
A: Cv values vary widely from <1 for small valves to >1000 for large valves. Check manufacturer specifications.

Q3: Does this equation work for gases?
A: No, this simplified equation is for incompressible fluids. Gas flow requires more complex calculations.

Q4: What affects specific gravity?
A: SG depends on fluid density - water is 1.0, seawater ~1.03, oils range 0.8-0.9, acids can be 1.2-1.8.

Q5: How accurate is this calculation?
A: It provides a good estimate for turbulent flow conditions. For precise calculations, consider additional factors like viscosity and temperature.