All valid points, except for one thing. Low pressure combo nozzles, particularly the 250gpm at 50psi will do everything your smooth bore will and still give a fog pattern if needed.
Having said that, I like the smooth bore attack also. Even with our combos we use a straight stream attack at the base of the fire.
Ok, help me out here. There is a combination nozzle manufactured today that operates efficiently at 50 psi? I have practiced "underpumping" a combination nozzle (not automatic) to achieve a desired flow. (i.e pumping a 2.5 combo nozzle at 75 psi to acheive 185 gpm, thereby flowing at a lower pump discharge pressure and decreasing nozzle reaction.) Example: 300' of 2.5 inch hose flowing 185 gpm = a friction loss of 24 psi, add 75 for the nozzle pressure (flat terrain with no FL) = 99 psi for pump discharge pressure with a nozzle reaction of 70 psi. Not bad for a fog nozzle.
However, maybe I need to do more research and study if there is a combination nozzle on the market today that operates at maximum GPM at a lower psi.(less than 100 psi).
I guess I should have prefaced my first post by saying that I was one of those firefighters that used to grab a line and run in without doing the math. Unfourtunately, no one in the department (not my current department) was doing the math either. We were simply using the standard 5 & 10 method for determining friction loss and starting the PDP at 100 psi.(Automatic nozzles) The result was brought in clear focus one day when an outside instructor arrived to do an hydraulics class. We were flowing 47 gpm (established by a flow meter at the nozzle) on a 300', 1.75 preconnect. How were we doing?
This same instructor turned me onto
solid bore nozzles and doing the math. The result was a much better understanding of hydraulics and "bombings" of subsequent structure fires. We were making huge stops and extinguishing the fire. Go figure.
As I said before, fog nozzles certainly have their place in the service, but give me a solid bore nozzle and a competent AO and we will certainly go take care of business.
Yes there are low pressure combination nozzles. We use them. The ones we use are 200gpm at 75psi and 250gpm at 50psi.
If you want more info e-mail me, I am happy to share what I know with you.
Yea, first you should know more about pumping a truck before making stupid comments like the one above. Yes you can pump different lengths and diameters and size smooth bore tips from your truck at the same time, if you are a real driver. It's called knowing your job, truck and the simple thing called gating back. Go learn your truck!
Originally Posted by K A
Now this is some funny schidt! A guy joins and his first post is to go back 13 years to try and start a fight with a guy no longer here?
BWAHAHAHAHAHAHAHAHAHAHAHAHAHAH AHAHAHAHAHAHAHAHAHAHAHAHAHAHAH AHAHAHAHAHAHAHA!
Nice try but sorry no points will be awarded!
First post: Check.
13yo Thread: Check
Picking fight: Check
That calls for a TRIPLE FACEPALM!Attachment 22240
A classic, but appropriate here.
Haha way to go... you sure told him Jgough!