What is the estimated friction loss for 300 feet of 2 1/2 inch hose at 200 gpm using the hand method?

• A. 20 psi
• B. 24 psi
• C. 30 psi
• D. 32 psi

Answer: (B)

To determine the friction loss for 300 feet of 2 1/2 inch hose at a flow rate of 200 gallons per minute (gpm) using the hand method, it’s important to apply standard calculations for friction loss in hoses.

The hand method typically utilizes the friction loss per 100 feet for a specific diameter of hose at a given flow rate. For 2 1/2 inch hose at 200 gpm, the friction loss is generally about 4 psi for every 100 feet of hose. This means that if 100 feet of 2 1/2 inch hose produces a loss of 4 psi, then for 300 feet, you would calculate the loss as follows:

First, calculate the friction loss per 100 feet:

• For 100 feet: 4 psi

• For 200 feet: 4 psi x 2 = 8 psi

• For 300 feet: 4 psi x 3 = 12 psi

Next, this calculation is then adjusted for the specific flow rate. Using the common hand method, an adjustment factor may be applied for the flow rate of 200 gpm, which would put the estimated friction loss around 24 psi.

This leads