For a 150 ft run of 2 1/2 in hose with a 1 1/8 in smooth bore nozzle, what is the minimum inlet pressure?

For a 150 ft run of 2 1/2 in hose with a 1 1/8 in smooth bore nozzle, what is the minimum inlet pressure?

• A. 60 psi
• B. 75 psi
• C. 85 psi
• D. 95 psi

Answer: (B)

The main concept here is that the inlet pressure must cover both the nozzle pressure and the friction loss along the hose. For a smooth-bore 1 1/8-inch nozzle, the standard nozzle pressure is 50 psi. The 150-foot run of 2 1/2-inch hose introduces friction loss at the flow produced by that nozzle; for this configuration, that loss is about 25 psi. Add these together (50 psi nozzle pressure + 25 psi friction loss) and you get a minimum inlet pressure of roughly 75 psi. If you supply less than that, the nozzle won’t reach the required 50 psi at the end of the hose; more than that is simply more than necessary for this setup.

The main concept here is that the inlet pressure must cover both the nozzle pressure and the friction loss along the hose. For a smooth-bore 1 1/8-inch nozzle, the standard nozzle pressure is 50 psi. The 150-foot run of 2 1/2-inch hose introduces friction loss at the flow produced by that nozzle; for this configuration, that loss is about 25 psi. Add these together (50 psi nozzle pressure + 25 psi friction loss) and you get a minimum inlet pressure of roughly 75 psi. If you supply less than that, the nozzle won’t reach the required 50 psi at the end of the hose; more than that is simply more than necessary for this setup.