Low pressure atomatic nozzle or Break apart with a 15/16 built in tip

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Permalink Reply by Michael Dombroski on October 9, 2011 at 1:21am

Hi Greg

We have used the auto nozzles down in our part of the world in the past, only to revert back to constant flow (apart from booster lines and aerial/deck nozzles).  The reason for this is that the nozzle man has no control over the flow rate with the auto nozzles.  A hose line can be flowing the maximum output of the nozzle one minute, and the minimum the next, without the MPO or nozzle operator knowing.  The flow rate on those things can vary immensly and they take all available water at their operating pressure.  When a second line is opened some of the 1st line's flow is diverted into that.  When a 3rd is opened the same happens etc.  This can mean a nozzle operator, who may be dealing with a large developing fire, may suddenly have a reduced flow at his nozzle due to another opening up, without any noticeable change in the pump or hose line pressure to enable the MPO to compensate.

A way of overcoming these issues to have flow gauges on the hose line outlets so the MPO can regulate flow with the pump speed.  We don't have these so we went back to constant flow nozzles for hose lines so an increased flow demand creates a pressure drop that can be compensated and nozzle operators have a constant flow to work with.

Hope this helps.  I'd be interested to hear more about break apart if you have any info on it (pressures / flows etc).

Mike D

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Permalink Reply by Shareef Abdu Nur on October 13, 2011 at 12:39pm

I prefer smooth bore nozzles over "automatic" nozzles any day of the week for interior attack due to simplicity, reliability, low operating pressures, and gpm delivery.  We all know that in order to combat BTU's we need GPM's and not PSI's.  The automatic nozzles are not constant in regards to flow.  The nozzle can go from optimum to minumum flow in seconds with no warning to the attack team.  Fire flow is simple math it is not rocket science.  Nozzle salesmen want to keep complicating this for us in order to sell nozzles. The smoothbore nozzle is the oldest nozzle in the fire service for a reason...It works!

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