What is the minimum inlet pressure required for a 150 ft of 2 1/2 in. hose with an 1 1/8 in. smooth bore nozzle?

• A. 50 psi
• B. 100 psi
• C. 75 psi
• D. 125 psi

Answer: (C)

When a handline is used, the supply pressure needed at the engine or pump side must cover two things: the pressure the nozzle needs to produce the stream, and the friction loss along the hose due to the water flowing through it. For a smooth bore nozzle of 1 1/8 inch, the standard nozzle pressure is 50 psi. The 150 feet of 2 1/2 inch hose carrying the flow from that nozzle produces about 25 psi of friction loss according to NFPA 14 hose friction charts for this flow. Add them together and you get 50 psi + 25 psi = 75 psi. So the minimum inlet pressure is about 75 psi.

The other options would either neglect friction loss (50 psi) or imply more pressure than is required for this setup (100 or 125 psi), which doesn’t align with the typical friction loss for this length and hose size at that nozzle flow.