BY KARL STAGGS
When it comes to supply-ing hoselines on the fireground, we all can handle the standard configurations. Most of us have pumped preconnects often enough or have standard operating guidelines that address our pump discharge pressures. When it comes to supplying nonstandard hoseline configurations, most of us rely on rules of thumb or have "cheat sheets" to determine our initial pressures until we have time to figure out actual friction loss (FL) for the setup.
One night when preparing to teach a hydraulics class at the local fire academy, I was reviewing a pump operator's handbook and came across the hand method for 21/2-inch lines and later found a hand method for 13/4-inch lines in a different book. I could not find a similar method for three-inch lines. So I started to play with numbers and count fingers. I think my 10-year-old daughter thought that I had lost my mind, sitting at the kitchen table muttering about coefficients, Q-squared, and doing something similar to Itsy Bitsy Spider.
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