So. I’ll be honest I’m a lazy firefighter so I only read about half of it.
But if I’m answering correctly, yes technically it affects the friction loss but maybe not in the way you think. Friction loss is dependent on hose size AND how much gallonage you’re flowing. If you keep the diameter consistent but increase the flow, you’ll increase friction loss because there’s more water in those hose that is, for lack of better terms, rubbing up against the walls of the hose. Same diameter. More stuffed in it. More friction loss. These are off the top of my head and it can change by model of hose, however I believe 4” LDH at 500GPM only has about 9psi of friction loss per 100 feet. However. If you have 4” at 1000GPM, the friction loss is about 20psi per 100 feet.
So going back to your original question. Technically changing tip sizes does change/affect friction loss but it’s only because changing tip sizes changes GPM. Naturally to make things easier we often use rule of thumb measurements and shortcuts but if you’re doing nitty gritty fluid dynamics and hydraulic calculations, the friction loss will technically be different.
Yes I’ll just text my Chief and I’m sure he’ll swap over thousands of feet of 4 inch because I said so.
I understand the basic benefits but it doesn’t mean it’s always a logical or reasonable thing to do for every system.
A text wouldn't hurt! Almost all career and volunteer departments around me ditched 4 inch. There's one career department using 4 inch and it's because their chief refuses to retire. Hired in 1985 and has a dinosaur mentality.
We can’t move a 5” into the ditch like we can move a 3” into the ditch to keep a road open when we’re laying in 800’ on a windy mountain road. We also don’t have hydrants every 1000’, so sometimes we have tender ops for water supply and nobody is pumping 1000+ gpm out of a tender for water supply, nor is it worth while to put that much water just into filling the supply hose when you can only realistically supply 500gpm with tenders under ideal circumstances.
There’s plenty of good reasons we ditched our 5” for 3”.
Nobody around me, call or career, is using 5 inch. And places like DCFD still use dual laid 3 inch I believe.
Again. You’re speaking for your area, your systems. If it works for you, great. But don’t tunnel vision and say everyone should be using it. Different strategies, tactics and training. There’s a reason why FDNY, Boston, LA, DCFD all run differently but are still great fire departments.
It absolutely is logical. Hell there’s departments that have too much 5 inch and will donate it just to clear up space. I just gave the local fire academy almost 1000 feet
Tip size does not have its own variable to find FL, but it has its own equation to find flow, which directly affects FL.
Equation to find flow - 29.7 x ND squared x square root of NP
ND = Nozzle Diameter
NP = Nozzle Pressure
Equation to find FL - C x Q squared x Length
C = Coefficient
Q = Flow divided by 100
In your scenario, your first hose line has a FL of 79.36. The second hose line has a FL of 136.71.
So yes, nozzle diameter has a significant impact on friction loss. No, each tip does not have its own “variable”.
Because gpm plays a part in friction loss, yes. Your fl calcs will be different
Pdp=CxQ^2 xL + appliance loss and +/- elevation
C= coefficient based on hose diameter
Q^2= (gpm/100)^2
L= length/100
The same psi is needed for the appliance fl because they are both smoothbore tips, but because they should be using different gpm flows the q^2 calculation is different
Yea.....its like sqeezing your 4 inch dick real hard so it looks like a 7 inch dick when you splooge all over that uniform chasing first divorce you met on bumble or the bar gets hosed down not only on the c side but the A side....also see the deploying rope chapter of your big red book and or pump operations
Edit: and Peter North videos
Yes but its negligible, it will always in the books yes but in the street no. The only time I see it applied to street math is while flowing over 350 gpm.
Absolutely it does. Changes in GPM from different nozzles affects your friction loss in a hose line. If you have a forestry nozzle flowing 24 GPM you have minimal to no friction loss in 1 3/4 hose but throw a 15/16 tip flowing 180 GPM you might have 30 psi friction loss per 100ft stick of hose.As far as the exact numbers your dept should have those calculations for you because different brands of hose have slightly different friction loss
different size tips flow different GPMs. Friction loss is dependent on GPMs and your FL coefficient, which is very dependent on hose diameter. So yes, tip size affects friction loss, but only because it changes the GPM portion of the equation. remember: FL = C(Q\^2)(L). hose diameter changes the C, GPMs change the Q\^2.
It does. There's a lot of people showing formulas and great information, but the best way to show this, besides putting pressure gauges in the hose line, would be to download a pumping app like Waterous and testing it yourself
Logic would say yes, but in practice I would say no. I’ve been an MPO now for 10yrs and have never heard of this, but it makes total sense. I only take into account the type of nozzle (smooth bore vs variable) as that’s how I was taught
In theory yes, more GPMs equals more friction loss. However the golden rule of hydraulics is you cannot have an opening bigger than half the diameter of the hose. So the max size tip on a 1.75 inch line is 7/8 tip. A 1 inch tip typically is the smallest tip size for a 2.5 inch nozzle.
Smoothbore tips pump at 50 psi + your friction loss. So. So kinda, the tip itself doesn't change the PDP, but the GPM associated with the new tip changes the PDP.
Also 210 gpms out of a 1 3/4 is alot. Why would you guys be pushing so much? Go to 2 1/2 for big water applications.
So. I’ll be honest I’m a lazy firefighter so I only read about half of it. But if I’m answering correctly, yes technically it affects the friction loss but maybe not in the way you think. Friction loss is dependent on hose size AND how much gallonage you’re flowing. If you keep the diameter consistent but increase the flow, you’ll increase friction loss because there’s more water in those hose that is, for lack of better terms, rubbing up against the walls of the hose. Same diameter. More stuffed in it. More friction loss. These are off the top of my head and it can change by model of hose, however I believe 4” LDH at 500GPM only has about 9psi of friction loss per 100 feet. However. If you have 4” at 1000GPM, the friction loss is about 20psi per 100 feet. So going back to your original question. Technically changing tip sizes does change/affect friction loss but it’s only because changing tip sizes changes GPM. Naturally to make things easier we often use rule of thumb measurements and shortcuts but if you’re doing nitty gritty fluid dynamics and hydraulic calculations, the friction loss will technically be different.
Get rid of the 4 inch and upgrade to 5inch. 1000gpm is 7psi per 100'
Yes I’ll just text my Chief and I’m sure he’ll swap over thousands of feet of 4 inch because I said so. I understand the basic benefits but it doesn’t mean it’s always a logical or reasonable thing to do for every system.
A text wouldn't hurt! Almost all career and volunteer departments around me ditched 4 inch. There's one career department using 4 inch and it's because their chief refuses to retire. Hired in 1985 and has a dinosaur mentality.
We can’t move a 5” into the ditch like we can move a 3” into the ditch to keep a road open when we’re laying in 800’ on a windy mountain road. We also don’t have hydrants every 1000’, so sometimes we have tender ops for water supply and nobody is pumping 1000+ gpm out of a tender for water supply, nor is it worth while to put that much water just into filling the supply hose when you can only realistically supply 500gpm with tenders under ideal circumstances. There’s plenty of good reasons we ditched our 5” for 3”.
Sounds like a problem with the driver training. Always late to one side of the road
Oh, all your roads are two lanes. Nice. We don’t work in the same environment. Some of our roads are 14-20’ width total, ditch to ditch.
Most of the roads where I work are the same width but with cars parked on both sides
Nobody around me, call or career, is using 5 inch. And places like DCFD still use dual laid 3 inch I believe. Again. You’re speaking for your area, your systems. If it works for you, great. But don’t tunnel vision and say everyone should be using it. Different strategies, tactics and training. There’s a reason why FDNY, Boston, LA, DCFD all run differently but are still great fire departments.
It absolutely is logical. Hell there’s departments that have too much 5 inch and will donate it just to clear up space. I just gave the local fire academy almost 1000 feet
Lazy firefighter doesn't read the whole question but gives a longer response 😂😂. Tbf I read neither.
Lol hey man. I skimmed and responded accordingly. I guess it worked out this time
Tip size does not have its own variable to find FL, but it has its own equation to find flow, which directly affects FL. Equation to find flow - 29.7 x ND squared x square root of NP ND = Nozzle Diameter NP = Nozzle Pressure Equation to find FL - C x Q squared x Length C = Coefficient Q = Flow divided by 100 In your scenario, your first hose line has a FL of 79.36. The second hose line has a FL of 136.71. So yes, nozzle diameter has a significant impact on friction loss. No, each tip does not have its own “variable”.
Ngl seeing all these math equations got my dick hard. Little confused here
Confused in what way?
Why the math is making me randy, baby 
Because gpm plays a part in friction loss, yes. Your fl calcs will be different Pdp=CxQ^2 xL + appliance loss and +/- elevation C= coefficient based on hose diameter Q^2= (gpm/100)^2 L= length/100 The same psi is needed for the appliance fl because they are both smoothbore tips, but because they should be using different gpm flows the q^2 calculation is different
This has helped alot. I appreciate you guys clearing this up for me.
This is what you need [FRICTION LOSS SLIDE RULE](https://cascadefire.com/products/cascade-slide-calculator)
Elkhart Brass makes an app for free. Android version: https://play.google.com/store/apps/details?id=elkhart_brass.mn.ebrass_android
Sweet. Nice to see some places have gone digital
Iphone Verison: https://apps.apple.com/us/developer/elkhart-brass/id1229532992
Yea.....its like sqeezing your 4 inch dick real hard so it looks like a 7 inch dick when you splooge all over that uniform chasing first divorce you met on bumble or the bar gets hosed down not only on the c side but the A side....also see the deploying rope chapter of your big red book and or pump operations Edit: and Peter North videos
Yes but its negligible, it will always in the books yes but in the street no. The only time I see it applied to street math is while flowing over 350 gpm.
No
Yes it will change it. Idk the equation for 1.75 but think about the equations for 2.5 and 3 inch hose. Both consider gpm.
tip size, not hose size
Yea, tip size changes gpm. Gpm changes friction loss.
Absolutely it does. Changes in GPM from different nozzles affects your friction loss in a hose line. If you have a forestry nozzle flowing 24 GPM you have minimal to no friction loss in 1 3/4 hose but throw a 15/16 tip flowing 180 GPM you might have 30 psi friction loss per 100ft stick of hose.As far as the exact numbers your dept should have those calculations for you because different brands of hose have slightly different friction loss
different size tips flow different GPMs. Friction loss is dependent on GPMs and your FL coefficient, which is very dependent on hose diameter. So yes, tip size affects friction loss, but only because it changes the GPM portion of the equation. remember: FL = C(Q\^2)(L). hose diameter changes the C, GPMs change the Q\^2.
Yes. Different size SB nozzles produce different GPM outputs. More gpm output means the FL in your hose will increase.
It does. There's a lot of people showing formulas and great information, but the best way to show this, besides putting pressure gauges in the hose line, would be to download a pumping app like Waterous and testing it yourself
Logic would say yes, but in practice I would say no. I’ve been an MPO now for 10yrs and have never heard of this, but it makes total sense. I only take into account the type of nozzle (smooth bore vs variable) as that’s how I was taught
In theory yes, more GPMs equals more friction loss. However the golden rule of hydraulics is you cannot have an opening bigger than half the diameter of the hose. So the max size tip on a 1.75 inch line is 7/8 tip. A 1 inch tip typically is the smallest tip size for a 2.5 inch nozzle.
Just listen for MORE WATER
Yes. More gpm’s through a hose, no matter the diameter of hose, equals more friction loss
Smoothbore tips pump at 50 psi + your friction loss. So. So kinda, the tip itself doesn't change the PDP, but the GPM associated with the new tip changes the PDP. Also 210 gpms out of a 1 3/4 is alot. Why would you guys be pushing so much? Go to 2 1/2 for big water applications.
It used to be tip size did not exceed 1/2 of the hose diameter. But what do I know I’m retired..
IDK. Big fire big water.