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Relay Pump Operations: Who Says It's Just for the Long Lay?

Paul Shapiro

Flow Test #2

Flow Test #2 This flow test also involved the use of 5” LDH SUPPLY HOSE with a maximum pressure of 185psi. This time the line was 300 feet long. The hydrant system was considered to be poor in volume and pressure. The first test from hydrant pressure was only able to produce a flow of 485 GPM. It should be noted that the initial static pressure on this hydrant was only 50 psi.

Even 5” hose was not able to produce the big numbers. And now for the relay pump operation. You’ve heard the old saying you can’t squeeze blood out of a turnip, well it’s hard to get big water from a hydrant that doesn’t have it. This is the case with this hydrant system. They had all the big water tools but the waterjust wasn’t in the ground. Setting up the relay was only able to produce 670 GPM, only 185 GPM more than the hydrant only evolution.

If this was the real thing and more water was needed, the IC would have to start looking for a hydrant that has the water to supplement the operations. Hydrants on a different main would be the best choice. Keep in mind that there is a good chance of that hydrant being several hundred feet away, thus requiring a relay pump operation for maximum flow.

Even 5” hose did not make a difference here due to a poor hydrant system.