Gated Wye Operations: Part 2 - Modern Flows (Ep #58)

In Part 2 of 2, Daryl Liggins and Dennis LeGear review gated wye operations with modern flows. A variety of different nozzle types are flow tested and shown are the implications that may arise. In Part 1 they went into detail about the historical evolution of gated wye operations and their use with legacy flows.
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[@nickp76]

What are some possible solutions that are being used to help correct these problems.

[@freefiresims2449]

nickp76 @fireengineering just had an article on this in last months issue. Pretty interesting stuff. The lesson I take away is to not use wyes for any modern fire attack. It worked for legacy, but not for what we face nowadays.

[@mattandersen6738]

@brogan healy A gated wye may be necessary in order to advance leader line and increase the reach of the hose itself, due to setbacks, long drives, etc.

[@mattandersen6738]

I do not believe the instructors in the video stated they were not using the pressure governor at all, which would account for the significant disparities between both the flow rate and the discharge pressures. All things bring equal and the two 1.75" lines are the same length, the friction loss only needs to be calculated for one line. Then, you would figure for the 2.5" truck line to the wye. You would not need to account for any friction loss in the gated wye until you reach 250 GPM, which is considered a master stream. Once you have that, you could establish your initial pump discharge pressure and set the governor to stay at that pressure. Then, when the second line is opened, the apparatus would automatically increase the RPM to compensate for the initial pressure loss when the nozzle is opened. When one nozzle is subsequently closed, the apparatus, still being governed by the pressure, would decrease the RPM and compensate for the brief increase in pressure to the first line. There would still be a momentary increase in the perceived nozzle reaction, but that would dissipate and the company could still function without being set back by significant nozzle reaction. Hope that helps. I've done that a lot and the physics still works.

[@jeffdeetz8472]

@@mattandersen6738In theory what you say is true, but when testing different makes of 2.5" and 3" hose, you will find significant differences in results. The governor may or may not pick up the pressure drop or increase properly. You need to test your specific layout and nozzle combinations.

[@KosukiFire]

Use two seperare lays, most engines have 2 crosslays, use both and avoid wye