What is the total friction loss in 500 feet of 3" hose with 2-1/2" couplings and 300 gpm flowing?

To calculate the total friction loss in a fire hose, various factors must be considered, including the length of the hose, the diameter of the hose, the type of fittings, and the flow rate. In this scenario, we are looking at 500 feet of 3-inch hose with 2-1/2-inch couplings and a flow rate of 300 gallons per minute (GPM).

For a fire apparatus operator, it is essential to understand that friction loss can be estimated using specific formulas or tables that account for both the diameter of the hose and the flow rate. A common practice is to use the friction loss per 100 feet of hose, which for a 3-inch hose flowing 300 GPM is generally around 3 psi per 100 feet.

To find the friction loss for 500 feet of hose, you would take the friction loss per 100 feet and multiply it by the length of the hose in hundreds of feet. Thus, the calculation is:

Friction loss = (Friction loss per 100 feet) x (Length in hundreds of feet)

In this case:

Friction loss = 3 psi x (500 / 100) = 3 psi x 5 = 15 psi

However