Gas Fitter Practice Test

If the air supply had fixed louvers reducing the air supply opening by 20%, how many square inches more are needed for air supply opening?

1. 261.25 sq in

2. 83.5 sq in

3. 61.2 sq in

4. 41.8 sq in

The correct answer is: 61.2 sq in

To determine how much additional air supply opening is needed when fixed louvers reduce the air supply opening by 20%, we must first understand that the original air supply area is decreased by a fixed percentage. When an opening is reduced by 20%, only 80% of the original area is effectively available for air supply. To calculate the additional area needed to compensate for this reduction, we can use the formula that describes the new required area to maintain the required airflow. If we set the original area as "X" square inches, the remaining effective area after reduction becomes 0.8X. To achieve the original airflow requirements, we need to establish how much additional area is necessary to bring the effective area back up to the original area value. The calculation is as follows: 1. Calculate the reduction: 20% of X is 0.2X. 2. To find the square inches needed to restore the original area, we need to compute the difference: \[ \text{X} - 0.8\text{X} = 0.2\text{X}. \] Thus, you need an additional area equal to the 20% reduction of the original area to meet the