1. What is a Water Flow Calculator (PSI)?

Definition: This calculator estimates the flow rate of water through a valve or orifice based on the flow coefficient, pressure drop, and specific gravity.

Purpose: It helps engineers, plumbers, and technicians determine water flow rates in piping systems for proper system design and analysis.

2. How Does the Calculator Work?

The calculator uses the formula:

Where:

• \( Q \) — Flow rate (gallons per minute, gpm)
• \( C_v \) — Flow coefficient (dimensionless)
• \( \Delta P \) — Pressure drop (pounds per square inch, psi)
• \( SG \) — Specific gravity of fluid (dimensionless, 1.0 for water)

Explanation: The flow rate is proportional to the square root of the pressure drop divided by specific gravity, scaled by the valve's flow coefficient.

3. Importance of Flow Rate Calculation

Details: Accurate flow rate estimation ensures proper system performance, prevents pipe damage from excessive flow, and helps select correctly sized valves.

4. Using the Calculator

Tips: Enter the flow coefficient (C_v), pressure drop (ΔP in psi), and specific gravity (default 1.0 for water). All values must be > 0.

5. Frequently Asked Questions (FAQ)

Q1: What is the flow coefficient (C_v)?
A: C_v is a valve's capacity to pass fluid, defined as flow in gpm of 60°F water with 1 psi pressure drop.

Q2: How do I find the C_v for my valve?
A: Check manufacturer specifications - typical values range from 1-10 for small valves to over 1000 for large valves.

Q3: What if my fluid isn't water?
A: Adjust the specific gravity (SG) - for example, use 0.79 for gasoline or 1.03 for seawater.

Q4: Does this work for gases?
A: No, this formula is for incompressible fluids like water. Gas flow requires different calculations.

Q5: What's a typical pressure drop in systems?
A: Residential systems often have 20-80 psi, with 10-30 psi drops across valves depending on design.