1. What is a Parshall Flume Flow Rate Calculator?

Definition: This calculator estimates the flow rate through a Parshall flume based on the measured head 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 (m³/s)
• \( k \) — Flume constant (dimensionless)
• \( H \) — Head (m)
• \( n \) — Exponent (dimensionless)

Explanation: The head measurement is raised to the power of n and multiplied by the flume constant to determine flow rate.

3. Importance of Parshall Flume Measurements

Details: Parshall flumes provide accurate flow measurements in open channels with minimal head loss, making them ideal for irrigation, wastewater, and stormwater systems.

4. Using the Calculator

Tips: Enter the head measurement in meters, flume constant (default 0.69), and exponent (default 1.55). All values must be > 0.

5. Frequently Asked Questions (FAQ)

Q1: How do I measure head in a Parshall flume?
A: Measure the water surface elevation at the specific point in the flume (usually 2/3 of the converging section length).

Q2: Where do I find k and n values for my flume?
A: These are typically provided by the flume manufacturer or can be determined through calibration.

Q3: What's the typical range for k and n?
A: k usually ranges from 0.38 to 3.07, while n ranges from 1.52 to 1.78 depending on flume size.

Q4: Can this be used for submerged flow conditions?
A: No, this calculator is for free-flow conditions only. Submerged flow requires different calculations.

Q5: How accurate are Parshall flume measurements?
A: Properly installed flumes can achieve ±2-5% accuracy under free-flow conditions.