Cfm To Pressure Calculator Conversion

Velocity Pressure Equation:

\[ VP = \left( \frac{CFM}{4005 \times A} \right)^2 \]

Velocity Pressure (VP):

Unit Converter ▲

Unit Converter ▼

From:	To:

1. What is Velocity Pressure?

Velocity Pressure (VP) is the pressure required to accelerate air from zero velocity to some velocity (V) and is proportional to the kinetic energy of the air stream. It's a key measurement in HVAC systems and airflow calculations.

2. How Does the Calculator Work?

The calculator uses the Velocity Pressure equation:

\[ VP = \left( \frac{CFM}{4005 \times A} \right)^2 \]

Where:

\( VP \) — Velocity Pressure (in wg)
\( CFM \) — Cubic Feet per Minute (ft³/min)
\( A \) — Cross-sectional Area (ft²)
4005 — Constant for standard air conditions

Explanation: The equation calculates the pressure required to move a specific volume of air (CFM) through a given cross-sectional area.

3. Importance of Velocity Pressure Calculation

Details: Accurate velocity pressure calculation is crucial for designing HVAC systems, determining fan requirements, calculating energy consumption, and ensuring proper air distribution in ventilation systems.

4. Using the Calculator

Tips: Enter CFM in ft³/min and area in ft². All values must be valid (CFM > 0, area > 0). The calculator will compute velocity pressure in inches of water gauge (in wg).

5. Frequently Asked Questions (FAQ)

Q1: What is the significance of the constant 4005?
A: The constant 4005 is derived from the density of standard air (0.075 lb/ft³) and accounts for unit conversions in the velocity pressure calculation.

Q2: How does area affect velocity pressure?
A: For a given CFM, a smaller area results in higher velocity and higher velocity pressure, while a larger area results in lower velocity and lower pressure.

Q3: What are typical velocity pressure values in HVAC systems?
A: Typical values range from 0.1 to 1.0 in wg for most commercial HVAC applications, though specific values depend on system design requirements.

Q4: Can this formula be used for non-standard air conditions?
A: The formula uses the constant 4005 which is specific to standard air conditions (70°F, 29.92 in Hg, 50% RH). For non-standard conditions, density corrections are needed.

Q5: How is velocity pressure related to total pressure and static pressure?
A: Total pressure equals static pressure plus velocity pressure (TP = SP + VP). This relationship is fundamental to fan selection and system balancing.