Friction Loss Explained

[@aronharper7001]

Thanks for this great refresher, I look like a damn genius to these young rookies

[@Jefftank61]

Sorry, if I confused you lol but you answered it perfectly. I appreciate your time & effort. I'm very big into learning & even re-learning! Thank you sir. I look forward to more videos.

[@Boxalarmtraining]

Thank you, glad you enjoyed it.

[@rogerwesthoff2492]

I thought it was very clear and concise. We have been having problems with manufacturers changing hose construction and altering the coefficients.

[@Boxalarmtraining]

For the 300' 2.5" line, if you are still using a 15/16" tip it will still flow 185 gpm. Your friction loss will be different though. It would be 7psi/per 100', so 21psi of friction loss. Your total Pump discharge pressure would be 71psi for that line.

[@Boxalarmtraining]

I will try to update this video soon to go into much more detail about these theoretical calculations. I will also try to add a fireground calculations video, which is much more usefull. It is just good to know where these numbers come from.

[@Boxalarmtraining]

I just used 95gpm to have a different problem. Just to change the scenario up. You can input whichever gpm you use to figure the correct Pump Discharge Pressure.

[@danielflores-xk2iy]

Cuál es la investigación científica que certifica esta fórmula

[@Boxalarmtraining]

I am unfamiliar with the task force & vari fog... Do you mean it is a Task Force Tips nozzle that is just an adjustable fog? You need to know the operating pressure and gpm of the Nozzle. It should be stamped on the nozzle or the gpms should be on the ring if it is adjustable galonage.

[@Jefftank61]

What do you suggest for a task force & vari fog & solid bore 1" 3/4 for the optimal gpms that you think is right? I'm getting 125 from my instructors but some people told me 150gpm? I''m a 13year mpo & I'm humbly trying to q/a our techniques & everyones #'s are contradictory to each other. We use 200' smooth bore (15/16") tip for our main attack speedlay & a back up 200' vari-fog 1 3/4" speedlay. We also use 2 1/2" 300' smooth bore or vari-fog attack for commercial. PLEASE HELP ME!

[@Boxalarmtraining]

I'm not sure I'm following you completely. The common operating pressure of a smoothbore handline is 50psi. A 15/16" tip at 50psi will deliver 185gpm. Then friction loss would be determined by 185gpm through 200' of 1 3/4" hose. Which would give you a friction loss of 53psi/per 100' which is 106 total friction loss for the 200' hose, you would have a Pump Discharge Pressure of 156psi. That is for your 200' smoothbore speedlay.

[@RyanBanman]

So I'm studying for firefighter now. I go in November for my hands on training. I am physically fit, I currently drive semi trucks like nobodies business, and I do desire the opportunity to serve as a ff.... ..but I am horrible at math. So to my surprise as I'm studying this stuff comes up!! Seriously, does this stuff really matter when your out on scene? Other than for maybe the people who design pumps and hoses, do you guys actually sit and figure this stuff while a fire is raging in front of you? Or do you just turn the pumps on, and give it more or less as needed? Can you tell me, as far as my exam is concerned in a if I flub the math portions of the exam, can I still pass the exam? I'm trying to watch some videos to help me get through it, but like I said, math and I don't get along.

[@Boxalarmtraining]

It is all dependent on your coefficient of friction. Some hose lines have different coefficients. Hale pump friction loss cards are probably not the same as a High Combat hose chart or any other brand. They are all slightly different but close.

[@Jefftank61]

why did you use 95 gpm for the last equation rather than 150 gpm?

[@Nootherlove1]

I appreciate you demonstrating these calculations, however, the Hale pump friction loss card says 150 GPM through an 1 3/4 hose yields 22.5 PSI per 100 ft. If you don't square the Q part of your formula it comes out exactly at 23.25. In addition I have pumped this at 150 at the pump with a fog nozzle and arrived with 150 gallons in a barrel in 1 minute. In other words your formula is too high for friction loss. I know you did not write it, but it miscalculates FL.

[@skymedic48]

I believe the hale pump cards, are under ideal "testing" situations. We learned this same formula, as the video, in fire school. When we test our hose, annually, we use these calcs to know exactly what each line on each pumper, will flow. The problem with the hale cards, is that as pumpers and pumps age, they don't account for decreased pump performance. That's why it's important to test your pumper, how you would actually flow at a fire. When we do flow tests, we can make up for whatever decrease there is.

[@chriswyse6703]

you're making it way harder than it has to be, charge the line and step on it

[@skymedic48]

You're not doing this on the fire ground, at least, you shouldn't be. Do this , BEFORE you get on the fire ground, then you have an idea where your pump should be, and adjust according to fire conditions, and what the nozzleman is telling you.

[@Boxalarmtraining]

I apologize. I will add “charge the line and step on it” to my delivery.