01-20-2001, 01:36 AM #26firelieut14Firehouse.com Guest
Most of our crosslays have TFT automatic nozzles (100 psi). Each engine has a 2 1/2" Blitz line off the rear which uses a smooth bore nozzle. Our high-rise packs (1 3/4") utilize smooth bore nozzles because they can operate at lower pressures than most automatic nozzles. If you loose a little pressure due to friction loss/gravity/poor pump pressure/etc...you still can operate the smooth bores at pressures around 50 psi...
01-20-2001, 07:32 PM #27Firefighter_RobFirehouse.com Guest
I'd like to mention something I heard awhile ago:
Imagine water coming from an automatic nozzle as millions of tiny droplets in either a tight formation, straight stream, or loose formation, fog pattern. No matter what the position, they are always going to be tiny droplets because the nozzle breaks the stream. Now imagine water coming from a smooth bore nozzle. It is not broken at all within the nozzle, so a true SOLID stream of water is flowing. Now that you have these two comparisons, through millions of droplets of water on a room and contents fire. The droplets of water are so close to droplets of steam, you get almost instanteous steam. However with the straight bore you get less steam because the fire has to heat a larger amount of water. I don't know if this is 100% true, but straight bores have been used since the creation of nozzles, why fix something that isn't broken?
"Interior to Command, send in another nozzle, this ones meltin'"
01-20-2001, 10:02 PM #28benford1Firehouse.com Guest
In our department, we use the Elkhart SM-20 for our 1 3/4 attack lines and we have both an SM-30 and a smooth-bore stack tip nozzle for our 3" lines. I have trained in some classes with the smooth bore 1 3/4 line and believe each one has an application. My advice to each of you is to have BOTH on hand and train with both, then you will know when to use which nozzle. One post mentioned the steam conversion with fog nozzles, which is perfect for a poorly ventilated structure. But if the fire has vented through the roof, then the steam goes right out the roof with all the heat and does not do the job.
The low pressure fog nozzles are a great tool to have. The line crew can handle the hose easier with less work, with a nozzle pressure of around 75 psi and a flow of 150 gpm. Once again, before you rely on these completely, add them to your tool box and train with them, then you will know when to use them.
No one nozzle does it all. It is best to have an assortment on the truck so you will have all your bases covered.
Train hard and fight hard. Be safe!
*****The opinions expressed are mine and do not necessarily reflect those of my department********
01-20-2001, 10:34 PM #29Capt. ZadaFirehouse.com Guest
I believe that the SM-20 & SM-30 are combination nozzles, but not automatics.
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