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2" attack line
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?
Replies to This Discussion
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Permalink Reply by NOVAFireman on
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Please take a minute and read this article by Battalion Chief Stone of Fort Walton Beach FD in Florida. http://countyfiretactics.com/2013/11/18/1-¾-for-commercial-attackwhy-not-2/
There is also a YouTube video attached to the article showing their test.
Is their test flawed too?
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Permalink Reply by Don Catenacci on
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How about YOU answer the question of what YOUR nozzle pressure is instead of deflecting every question asked to someone else's tests. I am asking YOU, not the Clay Township Indian Fire Department, or Battalion Chief Stone of Fort Walton Beach Florida, or even a YouTube video. It seems like a simple question...What is the nozzle pressure you are flowing to get 235 out of a 1 inch tip? Because you absolutely are not doing it at 50 psi at the tip.
The test you posted uses a 1 1/8 inch tip at 50 psi, with 140 psi of engine pressure, giving 45 psi per 100 feet of friction loss. With Ponn Conquest I can believe that is true. But the uncontrollable whipping he talks about is also absolutely true if you try to use nozzle handling techniques of the hose well in front of you. This is the main reason I am no fan of Ponn Conquest hose. We have never experienced that problem with our Key nitrile rubber hose, no matter what flow or pressure.
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Permalink Reply by Derek J Sinesi on
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This is a good article. But i fail to see anyplace in this article were we should take and throw the 2 or 2.5 hose out and run just 1 3/4". We have flowed big water from 1 3/4 hose. But you need 3 to 4 guys on it and that's a problem in today's volunteer fire service. Even though we have the man power to do so. The goal is to be able to cool things down, put more fire out faster with out using more man power to do so.
Second you can only beat the laws of physics for a while before it catches up to you and bites you in the rear.
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Permalink Reply by captnjak on
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Why is a 2 1/2 hose flowing 265 GPM so easily kinking? Is that typical for this hose? If so, why even carry it?
To the naked eye it didn't appear in the video as if they were flowing 260 GPM. I know it's not scientific, just my impression.
Aren't we still waiting for the explanation of how to do this at 105 PSI engine pressure?
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Mr. Catenacci,
There was no attempt to deflect questions, I was on 24 hour shift yesterday and replying from the back of the engine.
Our tests were conducted using 4 different engines, 2 separate in-line pressure gauges from different manufacturers, and one digital flow meter. Every gauge was in good working order and calibrated. The flow meter (also calibrated) was connected following the manufacturers instructions.
A series of initial flow tests were done using our old attack lines to ensure the accuracy. Those tests proved accurate.
Having proved the accuracy, we moved on to test the 1" integrated smoothbore with and without various Elkhart Chief tips. Those tips were 185@75, 200@75, and 200@50.
Out of the 1" we determined the following;
200ft, PDP=105psi, Flow=235gpm, NP=just under 40psi
Not questioning your experience levels, but we followed testing instructions as provided by the flow meter's manufacturer. I have also attended classes from various manufacturers on how to conduct hose and nozzle testing and those procedures were the exactly the same as we followed.
I personally emailed our data to Elkhart Brass and All-American Hose Company to ensure the data was correct, and to double check coefficient numbers for friction loss calculations. Both companies agreed with the information at hand, and provided coefficient numbers that did not match any past or current fire service hydraulics manual I can find. These new numbers are much lower than those in the manuals.
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Elkharts own smoothbore flow chart shows a flow of 210 gpm from a 1 inch tip at 50 psi, 188 gpm at 40 psi, 230 gpm at 60 psi. The flow from a 1 1/8 inch tip at 40 psi is 238 gpm.
Maybe you need to check the size tip you are using...The facts are the size of hose has absolutely NOTHING to do with the flow out of a smoothbore tip. No matter what size hose you use as long as the nozzle pressure is equal with all sizes of hose the flow has to be equal. That is a law of physics and hose size doesn't change that.
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Captnjak,
Even if it does kink why aren't they chasing kinks like I know your guys do and mine too. It sounds to me like someone may not be doing their job.
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Permalink Reply by Russ on
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Don stole my thunder. I used 2" for about 10 years when the chief phased it out. I personally like it for the low PSI/high GPM you can get from a straight tip. I also like the configuration of having it as one of three in a crosslay of 150' 1-3/4 with fog..200' 1/3/4 with a fog and 2" with a 200GPM straight tip
just my opinion
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We run water tonight through 2" line and our 1 3/4" both with TFT nozzles. Pump pressure set at 125psi. All that run the hand lines all decided they would grab the 2"line first. What we did notice was we were getting farther reach with the 1 3/4" by about 3'. I am believing this is due because of the age of our nozzles and they don't function the way they should.
Know we will have to decide what brand to go with. I personally have no preference.
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Permalink Reply by Bruce Lawrence on
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Seeing all the discussion on the flow calcs I contacted an old prof. of mine (PHD in Mathematics) and asked him to go over it with me. Will post his results once the scanner stops fighting with me, but bottom line was that the book charts are off by quite a bit...go figure...He thinks the reason is they are trying to build in a safety margin for firefighters so they have more than they think to help keep them non-toasty. The coefficient is where they made the adjustment according to his calculations.
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Bruce,
The biggest problem with any friction loss calculations today is that rarelyhave they been modernized to take into account new materials tht hose are made out of such as nitrile rubber hose, or hose where the liner is impregnated into the inner jacket of the hose. Add to that the fact that there are many hoses listed as a specific size, like 1 3/4, that are actually now somewhere between 1.88 and 1.95 inside diameter. It is obvious that if you are using coefficients that are for old style hose, that is actualy 1.75 inside diameter your calculations will be massively wrong.
To be brutally honest I don't believe what the manufacturers say about their hose size or friction loss figures. This is why both of my FDs have gone to using inline gauges and flow meters to get proper flows and pressures for our hoselines. One benefit of doing that is we found on our first out engine is that at 150 gpm we have roughly 50 psi friction loss in our crosslay pre-connect piping. That is simply outrageous, and by today's standards, completely unacceptable.
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