4 thoughts on “Attack Line Flows

    • if you are wanting 180gpm from a 1 3/4 handline, what pressure are you flowing and what nozzle are you using. This can be a difficult pressure to be aggresive with.

  1. A few years ago, while I was working in the Training Division, we flow tested all our nozzles and engines. Many in the department were surprised at what we found. I wasn’t, though. Generally, we found many of our constant pressure (automatic) nozzles were 35-50 gpm off from the expected gpm for a the manufacture’s recommended engine pressure for the particular nozzle and required flow. Additionally, we found many of our engine discharges were off by 10-20 psi. This was found to be that the pressure gauge on the pump panel read the pressure coming off the manifold near the pump, there was friction loss – significant in some cases – in the plumbing getting to the actual discharge port. Since this test, we now spec all engines with the discharge pressure / flow meter shall be within 36″ of the discharge port. Engine problem solved.

    As for our nozzles…we reconfigured our entire department’s inventory from automatic and constant / select gallonage nozzles to constant gallonage and smoothbore. We also went with low-pressure constant gallonage (175@50…250@50) nozzles to match the approximate flow of the 15/16′ and 1-1/8″ smoothbores. To offset issues with kinking and too closely match the smoothbores tips we went with a tip pressure of 60 psi. Lastly, we added to our arsenal the rapid attack monitor for some more punch.

    Flow rates:
    1-3/4″ lines are flowing 200 gpm from 15/16′ smoothbore or our low-pressure high-rise combo tip.
    2-1/2″ lines are flowing 270 gpm from a 1-1/8″ smoothbore or 350 gpm off the 1-1/4″ slug tip in the nozzle when you remove the 1-1/8″ tip.

    The minimum flow for an interior attack should be relative to the amount of fire you are going to fight. However, we made 150 gpm for 1-3/4″ lines and 250 gpm for 2-1/2″ lines are minimums. As you can see above, we are exceeding our minimum requirements.

    Great post !!

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