Questions and Answers

Issue 11 and Volume 112.

Questions and Answers DEPARTMENTS Quick Pressure Calculations To the Editor: There is a good explanation of “Quick Pressure Calculations” on page 149 of “Fire Service Hydraulics.” Can you supply the factors for three 2 1/2-inch lines into a deluge set using 1 1/4-inch, 1 1/2inch, 1 3/4-inch and 2-inch tips? R. B. Answer: The factors would be respectively: 1 1/4-inch tip—-1/12 nozzle pressure; 1 1/2-inch tip—1/8 nozzle pressure; 1 3/4-inch tip—1/5 nozzle pressure; 2-inch tip—1/3 nozzle pressure. The above should give approximate friction loss value with deluge sets operating at 80 psi, and reasonable values at any pressure between 60 and 100 psi. Vertical Lift To the Editor: What is the actual height a pumper lifts water? Is it to the center of the pump, the center of the intake or is it to the center of the gauge? B. R. Answer: The vertical lift of a pump is actually…

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