Using the condensed Q method, what is the friction loss in 500 feet of 3-inch fire hose flowing 300 gpm?

To determine the friction loss in 500 feet of 3-inch fire hose flowing 300 gallons per minute (gpm) using the condensed Q method, it’s essential to understand how the formula is applied. The condensed Q method uses the diameter of the hose, the flow rate, and the length of the hose to calculate the friction loss.

First, for a 3-inch diameter hose, the friction loss can be calculated using a standard coefficient. The general formula for the friction loss in hoses is:

Friction Loss (psi) = C × (Q^2) × (L)

where:

• C is a constant dependent on the diameter of the hose,

• Q is the flow rate in hundreds of gallons per minute, and

• L is the length of the hose in hundreds of feet.

For a 3-inch hose, the friction loss coefficient is typically around 2. If we convert the flow of 300 gpm into hundreds of gallons, that becomes 3. The length in the formula needs to be converted to hundreds of feet as well; 500 feet is 5.

Now substituting these values into the formula:

Friction Loss = 2 × (3^2) × 5

=