I just found out that we were awarded a grant for $24,000 to replace all the hose and nozzles on both engines. Right know we have 2 - 1 3/4" cross lays and 1- 2 1/2" cross lay. When i applied for this grant we thought we would go to 2" attack lines.
I keep hearing we won't like the 2" lines. I would guess some of you are using 2" hose so; Whats the good,bad and ugly of 2" hose?
Uhh... what are you talking about? First off, that wasn't DC. It was a volunteer department outside of DC. Second,
I'd question your numbers.
Your first sentence mentions your FD, DCFEMS, and your use of 1 1/2 inch hose. So THAT is what I am talking about. Secondly, I would hardly compare PGFD Company 33 of Kentland to a small rural FD. First of all, we don't have career firefighters from DC, the FDNY, and the rest of DC Metro area staffing our volunteer companies. We also don't staff our houses 24 hours a day.
Finally, sure they put the fire out with their 1 1/2 inch lines. But with the manpower they had there they EASILY vould have pulled a 2 1/2 and broke the back of that fire in less than half the time. Frankly, I don't care if you guys want to pull your low flow, small handlines and work your asses off for a longer period of time. We prefer a high flow, mobile line, that breaks the back of the fire sooner because most of our guys don't have all day, they have to go back to work.
We do what we do because it has a proven track record of working for us. You do what you do for whatever reason you choose to. I won't tell you to change, don't tell us we are wrong for not doing what you do.
I would tell you that is absolute nonsense.
Using the standard friction loss formula your friction loss would be almost 172 psi add 50 to that and your engine pressue would be 222 psi. Want to try again?
For 2 inch hose using the standard friction loss formula the friction loss would be 88 psi add 50 psi for the nozzle and the engine pressure would be 138.
Let's say you have the new miracle low friction loss 1 3/4 inch hose that is actually around 1.88 inch inside diameter. about halfway between 1 3/4 and 2 inch hose. So lets split the difference for engine pressure, it would still be somewhere arounf 180 psi.
Even figuring in some percentage of error becuase of hose design you are expecting us to believe you hose operates at almost 80 psi less than the formula would show. Sorry not buying it.
Odds are you are flowing 135 gpm at 50 psi, which gives you a pump discharge of around 105 psi give or take.
How long attack line do you need? we use extensively 1 "High pressure hoses (we define high pressure of 20 bar = approx. 290 PSI)
The hose is placed our pump on a "reel" and mounted directly to the pump containing about 2000 liters of water (530 U.S. gallons). it is a reinforced rubber hose. We can adjust the amount of water from 25 to 200 liters per minute. (About 6.5 to 53 U.S. gallons)
We have 2 High pressure hoses, one on each side of the pump and is between 60 to 90 meters. if we need more hose, we can extend them with each other.
We extinguis approx. 80% of our fires with this HP hose, car, container, houses, etc.. is it a fully developed house fire, we use standard 2" hose.
We can moneret a pipe on the nozzles so that we can make foam.
And I'm telling you that your tests, your gauges, or the salesman that ran the tests, are FLAWED. There is no way you flowed 235 gpm through 200 feet of 1 3/4 inch hose, and if it is Ponn Conquest it is actually 1.88 or greater, at 105 psi engine pressure. I could believe that flow at 100 feet, but not 200 feet.
By the way I know the formulas are flawed because of new hose construction and the fact that most 1 3/4 inch hose is actually bigger than that today.
I'm not sure why but about every other post I try to make here this damn site screws up and only posts half of it.
I don't need to make a trip to your FD to know your numbers are wrong.
The other problem with your numbers is that a one inch tip flows 209 at 50 psi. What nozzle pressure are you flowing 235 at? Because it isn't 50 at the tip unless you are injecting a friction reducing agent like RAPID WATER into the line. You can't beat the Laws of Physics that say a specific orifice flowed at a specific pressure flows a specific gpm, no matter what hose is attached to it.