Firefighter Practice Exam

How many psi of friction loss would correspond to 300 feet of 1 ½ inch hose if the loss at 100 feet is known to be 25 psi?

1. 50 psi

2. 75 psi

3. 100 psi

4. 150 psi

The correct answer is: 100 psi

To determine the friction loss in the hose, it's important to understand how friction loss is calculated based on the length of the hose. The relationship given states that for every 100 feet of 1 ½ inch hose, there is a friction loss of 25 psi. If we know the loss at 100 feet is 25 psi, then to find the loss at 300 feet, we can apply a proportional relationship. Since 300 feet is three times the length of 100 feet, we can multiply the friction loss for 100 feet by three to get the total friction loss over 300 feet. Calculating this gives: 25 psi (loss per 100 feet) × 3 = 75 psi. Therefore, the friction loss corresponding to 300 feet of 1 ½ inch hose is indeed 75 psi. The value of 100 psi would imply an increase that is not consistent with the proportionate increase in friction loss for the length of hose used; thus it does not accurately reflect the calculations based on the provided data.