Fire Service Pump Operator State Practice Test 2025 – Your All-in-One Guide to Exam Success!

To determine the correct percentage of friction loss in a 3-inch hose, it's essential to consider the standard calculations used in fire service hydraulics. The friction loss in hoses is calculated based on the diameter of the hose and the flow rate of water through it.

For a 3-inch diameter hose, the friction loss typically follows the guideline of approximately 2.5 times the square of the flow rate (in hundreds of gallons per minute (GPM)). As flow increases, the friction loss increases significantly due to the physics of fluid movement through a larger diameter.

In standard practice, friction loss percentage can vary depending on various factors such as the specific type of hose, length, fittings, and flow rates. However, in many training scenarios and practical applications, a figure of around 40% for friction loss associated with a 3-inch hose is commonly accepted. This reflects the understanding that larger hoses have a lower percentage of friction loss compared to smaller hoses due to reduced resistance.

Therefore, choosing 40% as the percentage for the friction loss in a 3-inch hose aligns with established fire service hydraulics principles.