Presentation on theme: "Discharging CAF Streams In reality anything that will let the stuff out of the end of the hose will work. The early mantra was that a shut off gate and."— Presentation transcript:
Discharging CAF Streams In reality anything that will let the stuff out of the end of the hose will work. The early mantra was that a shut off gate and a smooth bore tip was needed. Since Compressed air foam is essentially a finished product inside the hose, It needs only to be discharged from the end of the hose. At times only a shut off gate is used.
1 1/4” Smooth Bore Tip Larger bore tips (approaching the size of the hose) produce the smoothest, most unbroken stream of foam. The larger bore tips operate at low nozzle pressure which result in the least breakup of the foam discharge and a “dry” foam.
1” Smooth Bore Tip The stream expands at the point of exit from the nozzle tip. The smaller bore tips operate at higher nozzle pressure which result in the partial breakup of the foam discharge. The smaller tips are used to create a high velocity fire stream of “wet” foam suitable for fire attack that behaves as a fog jet. Smaller bore tips produce a more broken stream of foam
The combination stream nozzle will “strip” some of the air out of the foam bubble structure as the stream leaves the tip. The result will be a “wet” type of foam, which is very suitable for fire attack and is often preferred in room & content fires.
Automatic Combination Stream Tip The combination stream nozzle may diminish the stream reach of the line from that of the straight bore tip, but the stream will still have adequate reach for interior attack operations. Often combination nozzles are used when the system pressure makes straight bore nozzles unmanageable
The Water/Air Ratios In The Videos Were Different Than What Is Being Done Today The water/air ratio of the ’80s and early ’90s came from the Wildland/Urban Interface and from “Tribal Knowledge” of the earliest CAF systems. The ratio was 1 to 1 (gpm to cfm). The ratio is now more like 2 or 2 ½ to 1. We want a “wetter” foam. The “wetter” foam does the fast knock down and also has foam solution available to penetrate and finish the cooling process.
So….What should a 1 ¾” line flow? Get the water up at about 80 to 100 gpm The air flow will probably be about 30 to 40 on a 1” straight bore. Don’t sweat the details. If the stream has good reach, it is foamy, looks wet, and has some kick…….Go with it. You have the flow meters to check the details, but get used to just opening the valves to a certain point at a given pump pressure and leaving things alone.
So….What should a 2 ½” line flow? Do it with one of these. Otherwise, you’ll end up somewhere you don’t want to be…..(Back where you came from and upside down) These are 1 3/8” bore. Get the water up to 200 to 250 gpm.
This Is An Even Better Way This is the Akron version. Task Force developed the first one called the Blitzfire These can go to bigger bores such as 1 ½”. Get the water up to 300 or more gpm. The hose is light, so you can move one of these charged. Don’t try moving it while flowing