Firefighter Practice Exam

What would be the result if 100 feet of 1 ½ inch hose experiences a friction loss of 25 psi when the length is increased to 300 feet?

1. 50 psi

2. 75 psi

3. 100 psi

4. 150 psi

The correct answer is: 75 psi

To understand the result of increasing the length of the hose from 100 feet to 300 feet, we can apply the concept of friction loss in firefighting hoses. Friction loss typically increases linearly with the length of the hose. In this case, at 100 feet, the friction loss is measured at 25 psi. When the length of the hose is tripled to 300 feet, we can expect the friction loss to also triple. This is because friction loss is directly proportional to the length of the hose. Calculating it mathematically: if 100 feet results in 25 psi, then 300 feet can be calculated as follows: Friction Loss = (25 psi / 100 feet) × 300 feet = 75 psi. This means that with 300 feet of the same size hose, the friction loss would be 75 psi. Therefore, the correct answer reflects the linear relationship between hose length and friction loss, confirming that the result for 300 feet of 1 ½ inch hose would result in a friction loss of 75 psi.