Clyde McMillan, founder of Task Force Tips (TFT) allegedly designed the first automatic nozzle on a napkin in 1968 and constructed it in his basement in 1971. Clyde McMillan was the chief of the Gary (IN) Fire Task Force, a volunteer fire company established to provide professional assistance for the municipal fire department in Gary, Indiana regarding large structure fires.
Large structure fires require large volume water delivery, causing water supply issues that negatively influence the fire stream quality. At that time two basic types of nozzles are used for providing master stream, namely smooth bore nozzles and combination nozzles.
Both types are considered fixed-gallonage nozzles due to a specific nozzle pressure (NP) to produce the flow rate (gallons per minute, aka gpm) they need. This is a difficult goal to achieve at large-flow fires when the flow demands increase while the hydrant system pressures drop.
McMillan had been bothered by this problem for a while and started to find out a solution, which was the automatic nozzle. In terms of reach, this new type of nozzle can provide a quality stream even when water supply is uncertain.
Perhaps now you may be interested in how the automatic nozzle works. The key to maintaining a near constant pressure throughout the nozzle’s flow range is held by a pressure control unit calibrated to the required NP because the NP from the bottom of a nozzle’s flow range is slightly different from that to the top.
According to National Fire Protection Association (NFPA), an automatic nozzle’s NP range can be either plus or minus 15 pounds per square inch (psi) within its flow range. Let’s put it this way, the garden hose is simply an open-butt hose if it is not connected with a nozzle.
You can fill empty containers up with it for sure. If you want to get any reach like watering your lawn or washing your car, you need to create a hose stream at least by putting your thumb over the hose outlet, and let back pressure do its work. The question is that how you can use your thumb to maintain a decent stream to reach a flowerpot 15 feet away from you.
You must depress and retract your thumb like a madman to create a stream good enough to reach the target and get yourself exhausted before long. What you are busy doing with your thumb here in this case is exactly how the automatic nozzle works. The only difference is that the automatic nozzle can do a much better job without getting the operator exhausted.Anyway, the core concept of how the automatic nozzle works lies in how to maintain a near constant NP so that the desired stream can be produced. Basically, there is nothing different between an automatic nozzle and a fixed-gallonage nozzle when delivering water through a handline or master steam.
Adequate water is still needed to produce the required gpm. The friction loss for the required water flow in the hose must be calculated as well. The unique feature, however, of the automatic nozzle is that its stream reach quality can be maintained almost at the desired level once within the flow range of the nozzle, even if the gpm is not as required.
Failure to meet the required nozzle pressure will certainly reduce the stream reach, which can also be caused by the wrong size tip, inadequate water supply, or something wrong with the engine pressure.
When using smooth bore tips at a lower flow rate, firefighters can improve stream quality with smaller nozzle tips but this will cost them an extra time and some guesswork — the luxury firefighters can’t afford at the fire scenes.
Automatic nozzles, adjusting the flow automatically, save the firefighters from delay and guesswork caused by smooth bore nozzles.
