How many GPMs

[HotTrotter]

I am trying to find out how many GOM will flow through a hose at a certain pressure. For instance, I have 1 3/4" inch hose with a pressure of 125psi. How many GPMs will I get. I understand that the nozzle will change this number. I am looking for the best case scenario. Also assume that the pump is large enough to supply the necessary water. Obviously, if the hose is capable of suppling 200 gpm and the pump only delivers 100gpm, then the output will be 100.

[truckmonkey42]

Register with FH.com and get a profile or post your e-mail address and I can e-mail you a pump chart we have with all that info. For your scenario 125 will get 155gpm with the fog tip and will get 185 if you detach the fog and use the smooth bore. That is a 200' stick of 1 3/4".We use Elkhart Break apart nozzles with a 15/16" SB tip. For a Task Force fog nozzle, that same 125 will only get you 120gpm.
This will vary per every maunfacturer though depending on pump piping. So not every chart should be the same. For each engine you should actually go out and figure out your pump pressures and make you own charts. But generically speaking the numbers should be close.

[MG3610]

hose advice from a truck monkey......this cant be good :eek: :D

[hwoods]

Couple of Points: 1. As Truckmonkey said, we need a way to trade info without clogging the forums. If you have already registered, and got no response, there is a place in the Forums to use to communicate with the WT. Ask them what's up. 2. Go to www.MFRI.org That is the Maryland Fire and Rescue Institute's website, and they have downloadable training stuff, FREE.:)

[HotTrotter]

Yea, I registered, don't know what is going on. But thanks for the info, gave me exactly what I needed. And now I am off to a new web site Thanks Chief Woods. :)

[chattfiremike]

Ok Trotter i'm gonna try to help you from the pump operator IFSTA manual.
Ok the equation to figure what you want out also includes the friction loss its CQ2L Step 1. Obtain the friction loss coefficient for the hose being used (15.5) 1 3/4 hose.
Step 2. Determine the number of hundreds of gallons of water per min flowing Through the hose by using the equation Q=GPM

Step 3. Determine the number of hundreds of feet of hose by using the equation L = feet

Step 4. Plug the numbers from steps 1,2, and 3 into equation A to determine the total friction loss.

C=15.5 Q= GPM/100 L= hose length/100 FL=CQ2L.

Well trotter I leave it in your hands this is how you do it the rest is up to you brother. Hope this helps.

[truckmonkey42]

hose advice from a truck monkey......this cant be good :eek: :D

Did you see why I gave an example from a pump chart instead of actually using the formula like chattfiremike suggested.

Grunt grunt oo oo you want me open roof oo oo.

I do have a question though. If truckies are "truck slugs" and engine guys are "hose jockeys" or "water weenies" then what are you if you are assigned to a quint?

[LVFD301]

I do have a question though. If truckies are "truck slugs" and engine guys are "hose jockeys" or "water weenies" then what are you if you are assigned to a quint?

CONFUSED!

You don't know which way to lean

[Dalmatian190]

It may seem like a simple question.

In reality, it's pretty complex and this is where firefighting takes on the "craft" of understanding the various options and techniques (the art) and how it interacts with the engineering (the science).

The "simple" answer sometimes becomes 150gpm with a list of caveats longer than the fine print in a used car ad.

I am trying to find out how many GOM will flow through a hose at a certain pressure. For instance, I have 1 3/4" inch hose with a pressure of 125psi.

First, all calculations like this need at a minimum to have a length specified, since friction loss is a critical.

I'm also assuming the 125psi is the Pump Discharge Pressure and not the nozzle pressure

Let's chose 150' as the length of hose.

The nozzle is critical. Are we using a smoothbore? A low or standard pressure automatic nozzle? A constant gallonage nozzle?

150', 1.75" hose, 15/16" smoothbore tip will provide 180gpm.

How many GPMs will I get. I understand that the nozzle will change this number. I am looking for the best case scenario.

Best case for what? That's a pretty potent line for most structural attacks.

But let's say the situation is a leaking (and on fire) gas line and you want to use a fog line to approach and push the fire back so you can reach a shutoff.

You put on a standard 100psi constant pressure ("Automatic") fog nozzle. You're now only flowing a smidge over 100gpm unless the pump operator gets the pressure up. The nozzle itself maybe rated to flow 185gpm, but without sufficient volume and pressure behind it, it won't do it. It'll adjust the flow down until it achieves the 100psi nozzle pressure.

If you're using a constant gallonage nozzle and have it dialed down to the 35gpm setting that's handy for brush fires and overhauls...all you're gonna get in this scenario is...just about 35gpm best or worst case.

[FyredUp]

Actually unless you borrow or buy a flow meter or a pitot gauge you will NEVER know how much water is really coming out of the end of the hose at any given pressure.

Why? Because all of the formulas are basically questimates of how much water is flowing. Same with the manufacturers numbers. They are under ideal conditions with brand new hose. Also some manufacturers are marketing 1 3/4 inch hose that is closer to 2 inch than 1 3/4.

My advice...speak to your local equipment dealer and ask to borrow a flow meter for some serious hose flow testing. OR contact the manufacturer of your nozzles and ask them if they will lend you a flow meter. I have never had any difficulty borrowing a flow meter for testing.

We found that our pump pressures for our 2 inch preconnects were MUCH lower for the flows we wanted than the formulas said they should be. The flow meter proved that over the flows that we wanted.

Good luck and congratulations for being one of the few in this business that wants proof of what you are flowing instead of "well we always pumped that line at 120 psi so it must be right."

FyredUp

[CaptainGonzo]

Did you see why I gave an example from a pump chart instead of actually using the formula like chattfiremike suggested.

Grunt grunt oo oo you want me open roof oo oo.

I do have a question though. If truckies are "truck slugs" and engine guys are "hose jockeys" or "water weenies" then what are you if you are assigned to a quint?


Bi-trucksual!

[chattfiremike]

It kills me that people have the nerve to say anyone can be a firemen or you don't need a degree to do that. These posts proof that not anyone can be a firemen and it does take some smarts. Great work on all the info guys and gals.

[oscarb96]

hi...i dont know if you can send me that chart of pressures and flows you offer.in this post...i would be really thankful...my email is oscarperu@hotmail.com.... i am a volunteer firefighter in Peru en south america...thanks...

[Firespecialist]

Did you see why I gave an example from a pump chart instead of actually using the formula like chattfiremike suggested.

Grunt grunt oo oo you want me open roof oo oo.

I do have a question though. If truckies are "truck slugs" and engine guys are "hose jockeys" or "water weenies" then what are you if you are assigned to a quint?



A mutt..........(stupid 10 character thing.)

[Bones42]

Like FyredUp says above, get a flow meter if you want the actual numbers. Different manufacturer's hose will give you different flows. Calculations based on theories?

Keep It Simple, Stupid. Get a meter. I've never met a hose vendor that was unwilling to let a company borrow one. Flow water through the hose, with NO nozzle attached and that will give the GPM of the hose at different psi. Then start adding in your various nozzles and see what a difference the nozzles actually make, not what a saleman or theory says.

[the1141man]

Grunt grunt oo oo you want me open roof oo oo.


http://i6.photobucket.com/albums/y232/SDF_Soldier/geicofire.jpg

Truck work--so easy, even a caveman can do it!

;) :D

[CaptainGonzo]

http://i6.photobucket.com/albums/y232/SDF_Soldier/geicofire.jpg

Truck work--so easy, even a caveman can do it!

;) :D

:D Damn.. I nearly sprayed my monitor with coffee when I saw that! :D

[HotTrotter]

WOW!!! This got deep quick, I was just looking for a quick and dirty ball park figure. The origianl intent was to answer the question - If I have 1000 gallons of water and I am running 2 ea 1 3/4" attack lines how long befor I run out of water. The 150 gpm number works best here as that would give me about 6 minutes. Of course this also assumes that both attack lines are started at the same time. So my worst case answer is 6 minutes, but it reality it will probably be much longer, say 10 minutes.

I have gotten a slight bit of TMI here. :eek: Although it is good info.

I would like to thank everyone for their help and keep those comments coming :)

[Catch22]

WOW!!! This got deep quick, I was just looking for a quick and dirty ball park figure. The origianl intent was to answer the question - If I have 1000 gallons of water and I am running 2 ea 1 3/4" attack lines how long befor I run out of water. The 150 gpm number works best here as that would give me about 6 minutes. Of course this also assumes that both attack lines are started at the same time. So my worst case answer is 6 minutes, but it reality it will probably be much longer, say 10 minutes.

I have gotten a slight bit of TMI here. :eek: Although it is good info.

I would like to thank everyone for their help and keep those comments coming :)

In that case, you're going to be dependant on a lot of factors. Again, the flowmeter is a good idea.

However, if you want a pretty close estimate it may depend on your nozzles and what you pre-set them at. We have adjustable flow fogs pre-set at 125, so we'll get almost 4 minutes if we're flowing two on a 1,000 gallon tank (on your figure of running 2x 1 3/4" lines you'll actually get just over 3 minutes, not 6 ;) ). If you pre-set them at anything else, use that figure. If you pump them at anything different than the rated nozzle pressure, you'll have some math to do or use the flowmeter. At the same time, we figure our stacked tips at 50 psi nozzle pressure, so we're looking at 210 gpm with the smallest tip.

If you've got automatic nozzles, you're in a different situation altogether and you'll almost have to have a flowmeter and know what pressure you typically flow them at.

[snowball]

you could always fall back on the

GPM= 29.7 X (D2) X v- P (X .9 for open butt) ;)

L.A. City hydraulics...works for me!:D

[BGreve607]

Havent really been following in on this conversation, but are department just got new hose and we went from 1 3/4 to 1 1/2 and I was put in charge of making friction loss papers for this hose. Can you help me out

[DFW333]

http://www.akronbrass.com/pages/products/theoreticalfriction.htm


Hope this helps

[allineedisu]

I am trying to find out how many GOM will flow through a hose at a certain pressure. For instance, I have 1 3/4" inch hose with a pressure of 125psi. How many GPMs will I get. I understand that the nozzle will change this number. I am looking for the best case scenario. Also assume that the pump is large enough to supply the necessary water. Obviously, if the hose is capable of suppling 200 gpm and the pump only delivers 100gpm, then the output will be 100.



Are you a Firefighter?????

Are you a Motor Pump Operator?

Have you been through the course for Pump Operator?

If you have been through the training you should know this or even have been through basic firefigher training you should have been thaught thiese things.

From the questions you have asked in these forums, I seem to think that you aren't! Maybe a want-to-be or something.

We teach all the basic's during the first month of basic firefighter training.

Just my opinion.

[BGreve607]

Well I am a level 2 and do strictly volunteer right now, I start on my operators class in about a month, so theres your answer

[CaptainGonzo]

Havent really been following in on this conversation, but are department just got new hose and we went from 1 3/4 to 1 1/2 and I was put in charge of making friction loss papers for this hose. Can you help me out

Why would anyone take a step backwards when it comes to delivering the wet stuff to the red stuff?

[E229Lt]

If I have 1000 gallons of water and I am running 2 ea 1 3/4" attack lines how long befor I run out of water. The 150 gpm number works best here as that would give me about 6 minutes. Of course this also assumes that both attack lines are started at the same time. So my worst case answer is 6 minutes, but it reality it will probably be much longer, say 10 minutes.


I'm not too sure about how you figured this out, but given the above, I'd make these corrections:

Your flow from each line is about 180 gpm.
You have a 1000 gallon supply.
You are using 360 gallons per minute.
Your supply will last about 00:02:45.

[DocVBFDE14]

I'm not too sure about how you figured this out, but given the above, I'd make these corrections:

Your flow from each line is about 180 gpm.
You have a 1000 gallon supply.
You are using 360 gallons per minute.
Your supply will last about 00:02:45.

Please don't confuse him with actual firefighting figures and theories. The books you check out of the public library do not cover this type of information.

[HotTrotter]

Are you a Firefighter?????

Are you a Motor Pump Operator?

Have you been through the course for Pump Operator?

If you have been through the training you should know this or even have been through basic firefigher training you should have been thaught thiese things.

From the questions you have asked in these forums, I seem to think that you aren't! Maybe a want-to-be or something.

We teach all the basic's during the first month of basic firefighter training.

Just my opinion.

Yup, took all of those classes, did the calculations. But we never use it in real life. And if you don't use it , you lose it. What happens around here is we hook up the hoses and run them at 100 to 125 psi (depends who is on the hose), we keep the tank full and the portable pond full. No one really cares how many gpm we are using. :o

[HotTrotter]

I'm not too sure about how you figured this out, but given the above, I'd make these corrections:

Your flow from each line is about 180 gpm.
You have a 1000 gallon supply.
You are using 360 gallons per minute.
Your supply will last about 00:02:45.

I took the answers from the other posters. I'll be honest, I was lazy. I thought rather then spend hours trying to finds the info I would rely on my more intelligent colleagues who would have the answer on the tip of their tongues. :o I wasn't really looking for an exact number, just one that gets me close for an approximation.

[DocVBFDE14]

I took the answers from the other posters. I'll be honest, I was lazy. I thought rather then spend hours trying to finds the info I would rely on my more intelligent colleagues who would have the answer on the tip of their tongues. :o I wasn't really looking for an exact number, just one that gets me close for an approximation.


TRANSLATION: I have absolutely no clue what I am talking about. I want to seem smart but the only truthful part of this entire thread I started is "I was lazy." The only collegaue I have is the mouse in my pocket, and the support truck driver who takes the cool pictures of those firefighters I so want to be like, but alas "I was lazy" and didn't study so I couldn't pass the test.

[BGreve607]

Why would anyone take a step backwards when it comes to delivering the wet stuff to the red stuff?

as far as moving to smaller hose, we run a 3 man engine so you have the officer running the pump and the operator and the other on the hose and we can move 1 1/2 alot quicker than 1 3/4

[ThNozzleman]

as far as moving to smaller hose, we run a 3 man engine so you have the officer running the pump and the operator and the other on the hose and we can move 1 1/2 alot quicker than 1 3/4
Don't let the city administrators hear talk like this...they'll cut ya to one person and give you a garden hose.

[CaptainGonzo]

Why would anyone take a step backwards when it comes to delivering the wet stuff to the red stuff?

as far as moving to smaller hose, we run a 3 man engine so you have the officer running the pump and the operator and the other on the hose and we can move 1 1/2 alot quicker than 1 3/4

That's "bass ackwards."

The Officer should be on the hoseline with the nozzleman (thNozzleman if you are in Jefferson City, TN), not standing at the pump panel tuning and tweaking pressures.


PS: the weight difference between 1 1/2 and 1 3/4 is slight. If you can't handle that, may I suggest going to the gym and working out? I have pulled deuce and half with the same manpower..it's tough, but it can be done and it has been done until you can get more help to the scene.

[jtstoney]

I've been asked this question for 20 years, and the answer is the same.

The hose will will flow exactly what you put into it.

If you pump 100 gpm into it, it comes out 100 gpm.

If you manage to pump 1,000 into it, you would get 1,000 out.

The variance is the discharge pressure. Remember "friction loss" from academy?

What you need to be asking is what flow at what pressure.

JT

[Rescue101]

The difference between 1.5 and 1.75 can be over 50GPM.Why in the world would you go to the "short bus"?1.75 doesn't drag any harder and with the right nozzle delivers a lot more punch.Keep the pencil pushers out of the equasion,get something that works.And for JT,do you get 1000 gpm out of a 1000' of 4"? So much for the "you get out what you put in".Friction loss robs pressure and volume,although not at the same rate.Try it with two flow meters sometime.T.C.