What is the total pressure loss for 800 feet of 3-inch hose flowing 300 gpm according to the Condensed Q Formula?

To understand the total pressure loss for 800 feet of 3-inch hose flowing 300 gallons per minute (gpm) using the Condensed Q Formula, we first need to break down the components of the formula and how they apply to this scenario.

The Condensed Q Formula is used in fire hydraulics to estimate pressure losses in hose lines:

[

\text{FL} = C \times Q^2 \times L

]

Where:

• FL is the friction loss (in psi).

• C is the coefficient from tables based on the size of the hose.

• Q is the flow rate (in hundreds of gpm, so 300 gpm becomes 3).

• L is the length of the hose (in hundreds of feet, so 800 feet becomes 8).

For a 3-inch hose, the coefficient (C) is typically around 2.0, although it can vary slightly depending on the source.

Plugging in the numbers:

• C = 2.0 (for 3-inch hose)

• Q = 3 (300 gpm)

• L = 8 (800 feet)

The calculation becomes:

[

\text{FL} = 2.0 \times (