The CFM to FPS calculator helps determine the airflow velocity (measured in feet per second, FPS) from the volumetric flow rate (CFM) in ducts or pipes. This conversion is essential in various fields, such as HVAC (Heating, Ventilation, and Air Conditioning) systems, industrial processes, and environmental engineering. Understanding the relationship between CFM and FPS is important for optimizing air circulation, ensuring proper ventilation, and meeting system design specifications.
By using this calculator, engineers, designers, and technicians can easily convert the flow rate to velocity, ensuring that airflow meets operational standards. For example, knowing the FPS helps in choosing the right duct size and assessing system efficiency.
Formula of CFM to FPS Calculator
The formula for calculating FPS from CFM is as follows:
Where:
- FPS is the airflow velocity in feet per second.
- CFM is the volumetric flow rate in cubic feet per minute.
- Area is the cross-sectional area of the duct or pipe in square feet (ft²).
Steps for Calculating FPS from CFM
- Determine the Cross-Sectional Area (A):
- For a circular duct with diameter D (in feet), the area A is: A = π * (D/2)²
- For a rectangular duct with width W and height H (in feet), the area A is: A = W * H
- Convert CFM to FPS: Once the cross-sectional area is calculated in square feet, use the formula above to determine FPS.
- Adjust for Units if Necessary: Ensure that the area is in square feet (ft²) to match the CFM, which is in cubic feet per minute.
General Terms for Quick Reference
To help you with frequent conversions and prevent repetitive calculations, here’s a table of general terms and their corresponding values for various duct sizes. These can be useful for quick reference when working on airflow calculations.
| Duct Diameter (ft) | Area (ft²) for Circular Duct | Flow Rate (CFM) | FPS (Feet Per Second) |
|---|---|---|---|
| 1 | 0.7854 | 1000 | 1273.2 |
| 2 | 3.1416 | 2000 | 637.6 |
| 3 | 7.0686 | 3000 | 425.1 |
| 4 | 12.5664 | 4000 | 318.9 |
| 5 | 19.6349 | 5000 | 254.9 |
This table can assist in quickly estimating airflow velocity without the need for additional calculations.
Example of CFM to FPS Calculator
Let’s consider a rectangular duct with a width of 2 feet and height of 3 feet, carrying an airflow of 1200 CFM. We can calculate the FPS as follows:
- Calculate the Area (A): A = W * H = 2 ft * 3 ft = 6 ft²
- Apply the Formula: FPS = CFM / Area = 1200 CFM / 6 ft² = 200 feet per second
Thus, the airflow velocity is 200 feet per second.
Most Common FAQs
To calculate FPS for a circular duct, first determine the area using the formula A = π * (D/2)², where D is the diameter of the duct. Then, divide the CFM by the area to find the FPS.
Yes, the CFM to FPS calculator can be used for both types of ducts. For circular ducts, calculate the area using the formula for a circle (A = π * (D/2)²). For rectangular ducts, use A = W * H.
The results from the CFM to FPS calculator are accurate as long as the values for CFM and the duct’s cross-sectional area are correctly measured. Always ensure the units are consistent (feet and square feet) for precise results.