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Master Stream Operations: Bringing In the Big Guns

TFT’s automatic nozzle flowing 1250 GPM.

For obvious reasons, reach and/or penetration could enter into a defensive operation. The automatic nozzle is limited to a specific velocity and reach based upon the fact that the nozzle pressure is limited to one basic pressure range. This is not to say that the automatic nozzle pressure is not capable of delivering a good quality stream when reach and penetration is required. The smooth bore tips, selectable gallonage and fixed gallonage nozzles, on the other hand have a little bit more flexibility.

This is where this book will stray from the information that is published in today’s most common fire stream books. Remember, the books say that the above mentioned nozzles are rated to achieve their flows based on a specific nozzle pressure. The reason being, pressures higher than this will produce a broken stream. This is where this book disagrees. For maximum reach and penetration, high velocity/high pressure streams can be produced with extremely positive results as high as 150 to 200 PSI nozzle pressure depending on the specific nozzle and flow requirements.

The following smooth bore tip sizes with their corresponding nozzle pressure and flows have successfully produced high velocity/high flow streams:

1-1/2" tip @ 150 PSI NP  = 

817 GPM

1-3/4" tip @ 120 PSI NP


996 GPM

1-3/4" tip @ 150 PSI NP


1114 GPM

2" tip @ 100 PSI NP


1189 GPM

2" tip @ 110 PSI NP


1250 GPM

2" tip @ 120 PSI NP


1303 GPM

2" tip @ 140 PSI NP


1407 GPM

2" tip @ 160 PSI NP


1500 GPM

It should be noted that the 2"tip at 160 PSI NP produced a stream with a footprint reaching 360 feet.

The same high pressure operations can be applied to selectable gallonage and fixed gallonage nozzles. For the selectable gallonage nozzle, simply place the GPM dial on a lower flow setting and throttle up. For the fixed gallonage nozzle, all that is needed is to throttle up past the nozzle’s rated flow.

The following chart shows the selectable gallonage nozzle high pressure operation capabilities. A fixed gallonage nozzle has the same internal design as the selectable, the only difference being that the orifice cannot be changed. Therefore the numbers listed below will be the same for the fixed gallonage nozzle.

Selectable Gallonage

500 GPM Setting 750 GPM Setting
80 PSI NP 447 GPM 80 PSI NP 671 GPM
90 PSI NP 475 GPM 90 PSI NP 714 GPM
100 PSI NP 500 GPM 100 PSI NP 750 GPM
110 PSI NP 527 GPM 110 PSI NP 786 GPM
120 PSI NP 550 GPM 120 PSI NP 819 GPM

It should be noted that all nozzle pressures in these flow tests produced good working streams. Remember the reason for high nozzle pressure operations is to deliver hard hitting streams. If a higher GPM is needed, adjust the nozzle to the highest GPM setting.

The only requirements for safety with an operation like this are to not go over the maximum allowed inlet pressure of the appliance as well as to not exceed the required flow or nozzle reaction for the appliance, unless authorized by the manufacturer. Again follow all safety procedures for the actual operation of the gun as well as the continued maintenance inspections of the appliance and related plumbing.

The 2000 GPM fixed master stream appliance is very versatile. It is capable of the above mentioned high pressure streams as well as flows up to 2000 GPM not to mention the low flow operations in the 500 GPM range. The one drawback is that these large appliances are not capable of being adapted to the portable mode.

They are permanently attached to the discharge plumbing in the fixed mode. Developing the water supply for a 2000 GPM stream will be the challenge. As mentioned in Section 11, dual supply lines and/or a relay pump operation may have to be implemented to accomplish the 2000 GPM goal, even with LDH.

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