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Tools for air conditioning ducts
Four calculators to size, measure and plan the inspection of your ducts. No sign up.
These tools calculate the size of a duct from the airflow, the relationship between airflow and air changes per hour, the air velocity in a section and the level of attention your system needs. They are reference calculations: they do not replace an engineer’s design or a camera inspection.
Calculator 1
Duct size: from CFM to dimensions
Calculates the section and diameter of a duct from the airflow and the velocity you want to keep.
Usual reference values. The right value is set by the project.
How it is calculated. Section (in²) = CFM ÷ velocity (FPM) × 144. Diameter = √(4 × section ÷ π). Equivalent diameter of a rectangular duct = 1.3 × (a × b)0.625 ÷ (a + b)0.25.
Calculator 2
CFM and ACH: airflow and air changes
Converts airflow into air changes per hour, or the other way around, based on room volume.
How it is calculated. ACH = CFM × 60 ÷ volume (ft³). CFM = ACH × volume (ft³) ÷ 60. One cubic meter equals 35.31 ft³. One CFM equals 1.699 m³/h or 0.472 L/s.
Calculator 3
Air velocity in the duct
Calculates how fast air moves through a duct, from the airflow and the section.
How it is calculated. Velocity (FPM) = CFM ÷ section (ft²). One FPM equals 0.00508 m/s.
Planner
Duct inspection based on use
Estimates the level of attention your system needs based on how it is used and which signs it shows. It does not give a frequency in months, because there is no universal number.
How it works. Adds points for the type of space, the hours of use, the condition of filters and drain, and the signs marked. The decision to clean is made by a camera inspection, not a fixed calendar.
Terms
The basics of the calculators
What is CFM?
CFM stands for cubic feet per minute. It measures the airflow a system moves. One CFM equals 1.699 cubic meters per hour.
What are ACH?
ACH stands for air changes per hour. It shows how many times per hour a volume of air equal to the room volume is moved.
What is FPM?
FPM stands for feet per minute. It measures air velocity inside the duct. One FPM equals 0.00508 meters per second.
Do these calculators replace a design?
No. They are reference calculations. The system design is defined by an engineer with the project conditions, and the real condition of the ducts is only confirmed by a camera inspection.
Request an inspection
Before cleaning, it pays to look
The numbers guide you, but only a camera inspection shows the real condition of your ducts. Message us and we will confirm availability.
- +507 6388-2083
- info@climatizapanama.com
- Calle Gervasio García, 8, Panama City