Orifice Flow Calculator for Gas

Orifice Flow Equation for Gas:

\[ Q = C A Y \sqrt{\frac{2 \Delta P}{\rho}} \]

Discharge Coefficient (C):

Orifice Area (A):

m²

Expansion Factor (Y):

Pressure Difference (ΔP):

Density (ρ):

kg/m³

Volumetric Flow Rate (Q):

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1. What is the Orifice Flow Equation?

The orifice flow equation calculates the volumetric flow rate of a gas through an orifice plate based on the pressure difference across the orifice, fluid properties, and geometric characteristics of the orifice.

2. How Does the Calculator Work?

The calculator uses the orifice flow equation:

\[ Q = C A Y \sqrt{\frac{2 \Delta P}{\rho}} \]

Where:

\( Q \) — Volumetric flow rate (m³/s)
\( C \) — Discharge coefficient (dimensionless, typically 0.6-0.65 for sharp-edged orifices)
\( A \) — Cross-sectional area of the orifice (m²)
\( Y \) — Expansion factor (accounts for gas compressibility, typically 0.95-1.0)
\( \Delta P \) — Pressure drop across the orifice (Pa)
\( \rho \) — Density of the gas (kg/m³)

Explanation: The equation accounts for the relationship between pressure drop and flow rate through a restriction, with adjustments for energy losses (C) and gas expansion (Y).

3. Importance of Orifice Flow Calculation

Details: Accurate flow measurement is crucial for process control, instrumentation design, and system performance evaluation in gas piping systems.

4. Using the Calculator

Tips: Enter all parameters in consistent SI units. For standard orifice plates, C is typically 0.61. Y is 1.0 for incompressible flow or small pressure drops.

5. Frequently Asked Questions (FAQ)

Q1: What is a typical discharge coefficient value?
A: For sharp-edged orifices, C is typically 0.61. The exact value depends on the orifice geometry and Reynolds number.

Q2: When is the expansion factor important?
A: Y becomes significant when ΔP/P₁ > 0.02 (2% pressure ratio). For small pressure drops, Y ≈ 1.0.

Q3: What are common applications?
A: Orifice plates are widely used in gas flow measurement, HVAC systems, and process industries for flow monitoring and control.

Q4: What are limitations of this equation?
A: It assumes steady, fully developed flow and may need adjustments for very high velocities, non-ideal gases, or two-phase flow.

Q5: How accurate is this calculation?
A: With proper coefficients, accuracy can be ±1-2% of full scale under ideal conditions. Actual accuracy depends on proper installation and calibration.