Determining Engine Pressures Doesn’t Have to Be a Problem

Issue 7 and Volume 123.

etermining Engine Pressures Doesn’t Have to Be a Problem Associate Editor The pump operator encounters a multitude of hose layout problems on the fireground, but despite their almost infinite variety, he has to come up with an answer to only one question: What is the proper engine pressure? With one formula, a handful of rules and a few friction loss figures in his head, a pump operator can come up with his engine pressure answer. The only formula worth remembering, as far as a pump operator is concerned, is the one for friction loss in 211-inch hose, commonly written as: FL = 2Q2 + Q With this as a starter, a man can go far. What’s the friction loss in 211inch hose with 600 gpm flowing? Q is the number of hundreds of gallons a minute flowing, or gpm -4100. In this example, 600 -4100 = 6. So substituting in…

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