Hand Method for Calculating Friction Loss for Firefighters

[@Brian-hx9wy]

Currently going through pump ops now! I been driving and pumping for 8 years, now they want us to have the class 😑 I’m halfway through and these videos have helped me understand a little better. A good resource to recap the days teaching! Thank you from Florida!

[@richardkeilig8743]

Excellent class! I watch your videos often so I do not forget the main objectives and learning points.

[@Boxalarmtraining]

Thank you!

[@cbartoniv]

Explained very well! Thanks for posting! I watched/listened to all 7.

[@Boxalarmtraining]

clark barton IV Thank you very much. We are looking at producing more video series and hope to start them soon. We also have a nozzle series which goes fairly well with pump operations if you haven't seen it.

[@reviewgallery570]

Why do we need to close the(discharge) isolation valve of a centrifugal pump during startup⁉️ #pumpsolutions #pump #discharge #startup #energy #oilandgas #hazard #saftey #gas #renewableenergy techproces.com/centrifugal-pump/

[@FireForLunch]

So do you have a link for the video for the Subtract 10 method for 2.5?

[@cm12068]

I think the 12 multiplier is too much on the 1 3/4.

[@Kotten0429-Mason]

Will this work on a po practical.... also any difference in 2 inch hose

[@nick3572]

is there a hand method for 3 inch hose

[@jackbombajr7972]

Hello, I'm a firefighter in Brazil, in the city of São Paulo, I found this hand rule interesting, as it would be in our reality, do we use a one 30 meters 2.5 'hose, a derivative and a one 30 meters 1.5' hose more spray gun type?

[@benturner3320]

Great video!

[@Boxalarmtraining]

Ben Turner Thanks, I appreciate it!

[@reviewgallery570]

Why do we need to close the(discharge) isolation valve of a centrifugal pump during startup⁉️ #pumpsolutions #pump #discharge #startup #energy #oilandgas #hazard #saftey #gas #renewableenergy techproces.com/centrifugal-pump/

[@broscup]

Are these the current IFSTA methods? I know the older edition for 1 3/4" showed 9 for 125gpm and above and 12 for 100gpm. Looking around the nets I'm finding multiple versions.

[@Boxalarmtraining]

That is a very good question and I completely understand where you are seeing these. I am not sure why some texts have decided to change the 12 to a 9 on the hand method but my math puts the "9"" way under what the pressure should be. Ultimately, we have to get out a flow each of our own systems to see what the discrepancies are but here is an example: The actual FL for 200 GPM through 100' of 1.75" is 62 psi. Using the "12" hand method will get you 60 psi (pretty freakin close). Using the "9" hand method will get you 45 psi... This is pretty drastically lower than what it should be. Increase that to a very common 200' attack line using the "9" and you are 35 psi beneath the required nozzle pressure. We actually use a text book at our academy that shows both the "12" and "9" in different printings of the same text. I was told this was a typo but also saw it in a brand new text I was reviewing for a publisher. I'm not sure if I am helping at all but this is what I know... haha

[@broscup]

Thanks Matt. I was just reviewing and noticed the older book I had showed 9, but I also did the formula and noted that 12 is much closer all around to the formula. Thanks for the reply! You're definitely helping, keep up the good work!

[@MichaelGreenham]

Matt Hinkle I think the MFGS have started to change with the new High Combat technology that is giving more water w/ less friction loss. While I understand some people saying figure this out in the station and I agree. This type of "rough math" is helpful when you have to extend the hose load 100' on the fly. A fairly common occurrence when using a courtyard lay. In our 1st due. we have big houses on long driveways, with no hydrants (Tankers and drop tanks) At almost any instant your pre-connects get CHANGED to accommodate a need. These shortcuts help a lot.

[@Boxalarmtraining]

Yea, I have read other text books that show using the number 9 in the palm instead of the number 12. That will drop your friction loss down to something more like the High Combat or the Ponn Conquest. If you use a lower coefficient hose I would go with "9" if not I would stick with "12". Best thing to do is flow test your current setup to get a good baseline that way you know where to go from there.

[@apedrego1]

@@Boxalarmtraining The old method is a 9 multiplier, the new method is 12.

[@davidhopkins7998]

when I learned the hand method the multiplier for the 2.5" Hose began with 3 as the thumb number?

[@johnshobe1089]

I learned this way as well

[@johnshobe1089]

Other methods, like the drop 10 method, support started with 3.

[@nelsongomez164]

So you x 100x1 but when you use the 150 you x the # on 150 x the c(12) 36. Why you didn’t x 150x3x12. Confusing to me.

[@CKColovich91]

Not quite. The 100-200 is just the GPM from whatever nozzle you are using. Once you know what your GPM is, you then use the corresponding muliplier and multiply by “12”. Hope that helps. That will give you the FL per 100’.

[@nelsongomez164]

When you explain using the 246810 you were x the ist digit x the number in you hands. Here you did not use the coefficient. Confused, or maybe I am just stupid♑️♎️♐️🈚️

[@2010dlewis]

where's the other method you were talking about something 10 method

[@JT-pj4wv]

Dale Lewis did you ever figure out the drop 10 method? It’s good to know. It works for 2.5” hose. For example: an 1 1/8 smooth bore flows 265 gpms. So you would first drop the 5. Then subtract 10 from 26 which leaves 16. That’s it. Your fl is 16 psi per 100’ of 2.5” hose.

[@stevehutchinson119]

What is the multiplier if you are running 1.5" hose? thanks.

[@willdaniel3221]

Steve Hutchinson use the same method, should get you close to the adequate gpm required.

[@alexsheldrake6189]

It seems like that multiplier is a bit off. Generally speaking, at 125 GPM you can add 12 PSI per 50 ft of 1.75" to get your friction loss. And if my math is correct, you should get roughly 18 PSI of friction loss per 50 ft or 1.75" section at 150 GPM. It's just a quick and easy method to get roughly the correct pressure per section per GPM. I know it isn't super precise but I feel like the hand method you were using would put you way over your desired pressure. Or maybe I am overlooking something. Does anyone else agree or am I pumping incorrectly?

[@Boxalarmtraining]

This hand method uses coefficients provided from a text book when this video was produced. The coefficients vary greatly depending on the hose construction and actual internal diameter. There is a significant different in coefficients between a 1.75” and a 1.88” internal diameter but both of those hoses are called an 1 3/4”. The only way to actual determine your PDP is to test your own hose lines and attack packages. Even a 50’ hose line is not actually 50’. If you open the box on several sections of new hose that are labeled 50’ they will almost never actually be the same length. I’ve seen hoses differ by more than 5’ but both called 50’.

[@TheMajestikm00se]

I'm sorry, but even this is just too complicated for use on the fireground. As stated in the beginning, it doesn't account for elevation, or other factors. So what's the point? I know I want 140 psi on the panel when I pull 200' of 1 3/4" with a 100 gpm fog nozzle (standard crosslay on my engines). If I need more or less pressure I ask for it. Sit down, in quarters, and figure this out without clever shortcuts for typical configurations, and make an easy to read chart. That is your starting point, then listen to the guy on the nozzle.

[@Boxalarmtraining]

That's perfectly fine for your operations and I prefer charts exactly like you are saying. I made this video to explain this method because many get confused and have to learn it for tests or promotional exams. Some actually like this method but my experiences generally lead to finding the method(s) you prefer and sticking to them. If you like pre-planning and making charts then I couldn't agree more. Glad to hear you all are taking the time to do that.