1. What is a Parshall Flume Flow Rate Calculator?

Definition: This calculator estimates the flow rate through a Parshall flume in gallons per minute (gpm) based on head measurement and flume characteristics.

Purpose: It helps hydraulic engineers and water management professionals measure open channel flow rates accurately.

2. How Does the Calculator Work?

The calculator uses the formula:

Where:

• \( Q \) — Flow rate (gpm)
• \( k \) — Flume constant (dimensionless)
• \( H \) — Head (m)
• \( n \) — Exponent (dimensionless)
• 448.831 — Conversion factor (gpm/(m³/s))

Explanation: The head measurement is raised to the power of n, multiplied by the flume constant, then converted to gpm.

3. Importance of Flow Rate Measurement

Details: Accurate flow measurement is critical for irrigation systems, wastewater treatment, and environmental monitoring.

4. Using the Calculator

Tips: Enter the head measurement in meters, flume constant (default 4.0), and exponent (default 1.55). All values must be > 0.

5. Frequently Asked Questions (FAQ)

Q1: What is a Parshall flume?
A: It's a fixed hydraulic structure used to measure flow in open channels with minimal head loss.

Q2: How do I measure head (H)?
A: Measure the water level at the specified point upstream of the flume throat, typically 2/3 of the converging section length.

Q3: Where do I find k and n values?
A: These are determined by flume size - consult manufacturer specifications or hydraulic engineering references.

Q4: Why the conversion factor?
A: The formula typically gives m³/s, so we multiply by 448.831 to convert to gallons per minute.

Q5: What's the accuracy of this calculation?
A: Properly installed Parshall flumes typically have ±2-5% accuracy when using correct k and n values.