Air Knife Airflow & Sizing Calculator
Determine the precise airflow (m³/h) required for your air knife system, or calculate how many air knives your current centrifugal blower can support based on a standard 110 m/s target velocity.
How Airflow Requirements are Calculated
CHANGESO utilizes standard fluid dynamics formulas to determine the precise volume of air required to achieve a high-impact drying curtain. The core formula to find volumetric flow rate (Q) is Flow = Area × Velocity.
- Area Factor: Length (mm) × Gap (mm) gives the exit area of the air knife.
- Target Velocity: For effective industrial water blow-off, CHANGESO standardizes the target air velocity at 110 m/s.
- Constant 0.0036: The unit conversion factor to translate mm² and m/s into the standard industrial unit of cubic meters per hour (m³/h).
- By simplifying this at 110 m/s, our calculator uses the rapid estimation coefficient of 0.396 (110 × 0.0036).
Air Knife Sizing FAQ
Example: What size blower do I need for a 500mm air knife with a 1.0mm gap?
To achieve an effective 110 m/s drying velocity, multiply the length (500) by the gap (1.0) and our velocity constant (0.396). The formula yields 500 × 1.0 × 0.396 = 198 m³/h. You would need a regenerative blower capable of delivering at least 198 m³/h of continuous airflow.
How many 630mm air knives can a 3100 m³/h blower support?
This uses Mode B of our calculator (Reverse Sizing). First, find the airflow required for one knife with a standard 2.0mm gap: 630 × 2.0 × 0.396 = 498.9 m³/h. Divide the total blower capacity by this requirement: 3100 / 498.9 = 6.21. Therefore, the blower can safely support 6 individual air knives.
Why is 110 m/s the standard target velocity?
Extensive testing in food and beverage bottling lines shows that 110 m/s (approx. 22,000 FPM) is the optimal aerodynamic sweet spot. Velocities lower than this may leave residual droplets, while significantly higher velocities waste energy and create excessive noise without adding proportionate drying benefits.