Select the best answer for the question.
What's needed to calculate the CFM required to provide a given number of air changes in a building?
A. Floor area, ceiling height, and fan horsepower
B. The floor area, ceiling height, and an enthalpy chart
C. The floor area and ceiling height
D. A psychrometric chart and an enthalpy chart
Answer (2)
CFM (Cubic Feet per Minute) is needed for air changes in a building.
Volume of the building is calculated using floor area and ceiling height.
CFM is calculated by multiplying the volume by the desired air changes per minute.
Therefore, floor area and ceiling height are needed to calculate CFM: C
Explanation
Understanding the Basics To determine the CFM (cubic feet per minute) required for a given number of air changes in a building, we need to understand the relationship between CFM, the volume of the space, and the air change rate. The volume of the space is determined by its floor area and ceiling height.
The Formula The formula to calculate CFM is: CFM = V o l u m e × A i r C han g es p er M in u t e Where:
Volume is calculated as Floor Area × Ceiling Height
Air Changes per Minute is the desired rate of air change.
Identifying Required Parameters Therefore, to calculate the CFM, we need the floor area and the ceiling height to determine the volume of the space. Other factors like fan horsepower, enthalpy charts, and psychrometric charts are not directly required for this basic CFM calculation.
Selecting the Correct Answer Based on the analysis, the correct answer is: O C. The floor area and ceiling height
Examples
Imagine you're designing a ventilation system for a classroom. To ensure the air is refreshed adequately, you need to calculate the CFM required. Knowing the classroom's floor area and ceiling height allows you to determine its volume. Multiplying this volume by the desired air changes per minute gives you the necessary CFM for the ventilation system. This ensures a healthy and comfortable learning environment for the students.
To calculate the CFM required for a specific number of air changes in a building, you need the floor area and ceiling height to determine the volume of the space. You then multiply this volume by the desired air changes per minute. The correct answer is C: The floor area and ceiling height.
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