How long must a ventilator rated for 450 ft³/min run to assure 3 air changes in a confined space of 10' by 24' with an 8' ceiling?

To determine how long a ventilator rated for 450 cubic feet per minute (CFM) must run to achieve 3 air changes in a defined volume, it's essential to first calculate the total volume of the confined space and then establish the requirement for air changes.

The volume of the space can be calculated using the formula for the volume of a rectangular prism: length × width × height. In this case, the dimensions are 10 feet (width) by 24 feet (length) by 8 feet (height).

Calculating the volume: Volume = 10 ft × 24 ft × 8 ft = 1920 cubic feet.

To achieve 3 air changes, the total volume of air needed to be moved is 3 times the volume of the room: Total air to be changed = 3 × 1920 ft³ = 5760 ft³.

Now, with the ventilator rated at 450 CFM, we can calculate the time required to move the 5760 cubic feet of air. The time can be determined using the formula: Time (in minutes) = Total air volume to be moved / Airflow rate.

Substituting the values gives: Time = 5760 ft³ / 450