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Training >> Browse Articles >> Water Flow Technology by Paul Shapiro

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Master Stream Operations: Bringing In the Big Guns



It is extremely important to have the capability of producing the best possible stream with the delivery appliance of choice. This, of course, will have a direct effect on achieving the quickest possible knockdown. Throughout the years most of the attention has been given to the handline. There have been several types of nozzles used with various techniques. All have claimed success with their weapons of choice.

Master streams, on the other hand, seem to have been and continues to be, status quo, no big discussions and no new techniques for operations. The reason there hasn’t been much said about the master stream is because of its infrequent use as compared with the more common and debatable handline evolutions. Master stream operations are more commonly used in a defensive surround and drown operation where the goal is to dump a lot of water onto a fire that has probably burned through to the outside of the building. It’s pretty basic.

Here is a common definition of a master stream: A master stream is a heavy caliber stream delivered through a master stream water delivery appliance. A master stream is used when flows surpass 350 GPM becoming to difficult to be delivered from a handline operation due to nozzle reaction. The stream that a master stream operation produces is high in flow and usually in the form of a straight stream using a smooth bore tip or some type of combination nozzle.

There are three types of master stream operations, the fixed master stream, the portable master stream and the elevated master stream. There are two types of master stream nozzles, the smooth bore tips and the combination nozzles. The following information about master stream nozzles can be found in most fire stream management books in circulation today. It’s information that needs to be understood to establish a base to operate from.

The most common set of smooth bore tips that come with a master stream is what is known as the stacked tips. The stacked tips get its name because it consists of four tips connected into one stack, which is then attached to the master stream appliance. The tip sizes and the corresponding flows are based on a 80 PSI NP:

1-3/8"

 – 

502 GPM

1-1/2"

 – 

598 GPM

1-3/4"

 – 

814 GPM

2"

 – 

1063 GPM

For master stream appliances capable of flows higher than 1000 GPM flows the following tip sizes with 80 PSI nozzle pressures will apply. Again these are the most common:

2-1/4"

 – 

1345 GPM

2-1/2"

 – 

1661 GPM

2-3/4"

 – 

2010 GPM

It should be noted that the standard rule on smooth bore tip nozzle pressures used with master stream operations is to use a nozzle pressure of 80 PSI. Nozzle pressures higher than this will create a broken and insufficient stream, according to most fire stream books. In the fixed and elevated master stream portion of this section smooth bore tips will be taken to a much higher level producing high pressure streams that were never thought possible.

The combination master stream nozzle family has three types that are in service today. They are selectable gallonage, fixed gallonage, and automatics. The selectable gallonage nozzle has several flow settings that are manually set from some type of adjustment mechanism by the firefighter. All of the settings are based on a specific nozzle pressure (usually 80-100 PSI) for the nozzle.

The fixed gallonage has one specific flow designed into the nozzle based on the nozzle pressure. Again 80-100 PSI is the most common. With the selectable gallonage and the fixed gallonage nozzles, flows higher and lower than the nozzles rated flow are possible. The nozzle pressure will either be lower or higher than the rated nozzle pressure, depending on the flow.

The automatic nozzle maintains a near constant nozzle pressure throughout the entire flow range of the nozzle itself. This allows the stream quality to be adequate throughout the flow range. 80-100 PSI is also the most common nozzle pressure. It should be noted that the automatic nozzle is the most common of the combination nozzles in service today.

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