1. #1
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    Default Dummies Guide to Hydraulics

    This surely has been poste don here but I can't find it.

    Is there an easy to understand hydraulics guide somewhere?

    Keep in mind:

    1) I suck at math

    2) Everything I've read on here makes my head hurt after 5 minutes
    I am a highly trained professional and can find my :: expletive deleted:: with either hand in various light conditions.

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    Practice practice practice. I had the same problem at first but i would sit at the fire station and have one of the older jakes make up problems for me to figure out.
    Hello. Fire dept.. You light'em, We fight'em!

    "hard working, gear jamming, nail driving, "jake". "

    IACOJ
    4-16-2010 "On the approach"

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    Flash cards with all of the different friction losses, gpm's, tips sizes and hose sizes worked for me. Repitition and doing problems on a board and then on the pump panel.

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    although not 100% accurate for the "hydraulics" junkies. I was first taught how to pump a truck like this.

    Fog Nozzle 100psi
    Master Stream 80 psi
    smooth handline 50psi

    add 10 psi for every 100ft of handline
    add 5psi for everyfloor above the first
    pump a standpipe at 150psi
    never send more than 100psi to any truck if relay pumping

    i think thats about it. practice running multiple lines at multiple pressures without alot of pressure jumps is what makes you proficient. Pay attn to your guys. they will let you know how the line feels

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    What we had done is ran lines off at 200 ft with the various tip, nozzles, and appliances. We then pitot'ed them and used flow meters. Found out FL then in 100 ft incriments. We then made liminated "cheat sheets" and pinstriped the preconnects for the lengths appropriate to the x-lays.

    PM me and i'll send what I have.

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    10psi per 100 is way too low, maybe if it was a line heading downhill. more like 15-20 for 1.75 inch line.

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    Thumbs up

    The flash card idea worked for me too. I also hate math but the more I studied hydraulics the more it made sense. Too bad I didn't have any firefighters for math teachers in high school. Study Hard, FOREVER!

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    Quote Originally Posted by DonSmithnotTMD View Post
    This surely has been poste don here but I can't find it.

    Is there an easy to understand hydraulics guide somewhere?

    Keep in mind:

    1) I suck at math

    2) Everything I've read on here makes my head hurt after 5 minutes
    The Three Rules of the Fire Service--

    1) Pump at 150

    2) Cook at 325

    3) Beg for forgiveness,don't ask for permission.




    ------------or------------------


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    Quote Originally Posted by jonnyirons2 View Post
    10psi per 100 is way too low, maybe if it was a line heading downhill. more like 15-20 for 1.75 inch line.
    it does become exponentially inaccurate the longer the stretch gets over 300ft. for depts using preconnected 200ft 1 3/4 handlines it should be ballpark flowing 95-125gpm. and is more than generous for 2.5in hose.

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    thumb up means more pressure
    thumb down means less pressure
    The Box. You opened it. We Came...

    "You'll take my life but I'll take your's too. You'll fire musket but I'll run you through. So when your waiting for the next attack, you'll better understand there's no turn back."

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    Thumbs up

    Quote Originally Posted by JHR1985 View Post
    thumb up means more pressure
    thumb down means less pressure
    The problem with the thumbs up, thumbs down is that it doesn't account for the problem you may be having. KINKS could be cause the pressure drop.

    Perhaps you should invest sometime in becoming familiar with the GPM rating of your equipment. I would suggest that you determine what target flow you are trying to achieve at a fire, with a given size line. Once you have figured that out get a smooth bore nozzle, they come in various sizes which governs the GPM rating, and put it on the end of 100' of the hose you are using. Take the pressure up to fifty pounds of nozzle pressure, measured while flowing with a pitot gauge. As an example: A 15/16" tip, we have learned, loses 30 psi in 100' of 1.75" hose. We learn this by flowing water and using a pitot gauge to study it. If we wanted to achieve the same flow with an automatic nozzle, since it operates or is designed to, at 100 psi, we would take the starting figure, 50 or 100, and add 30 to it for every 100', or 15 to it for every 50' of line. The operating figures can all be pre-determined with lines of a known length.


    It can also be determined with a reverse stretch. If the working length is known, as an example 100' of 1.75" line filled out with 2.5", simply start adding 50' of line and taking a reading each time after making the throttle increases. Record the numbers. Mark the hose in some fashion, so that the hose numbers are on each end of the hose, and perhaps each side. When the hose is packed into the Engine record each number onto a sheet in it's position. A chart can be made that shows the hose number, the length it is from the nozzle, and the known loss for this distance. Ex: after a stretch the driver looks at the coupling they are attaching to the pumper. On the end of it is a number, they look at the chart taped on the inside of the cabinet door. It shows that hose # 6534 is 250' behind the 100' working length. The pressure should be X. It is as simple as looking of the sheet and throttling the engine up to that pressure. We have had situations where nozzle peolple were screaming for more pressure and have had drivers with the confidence to be able to say, " my pressure is right you have a problem elsewhere." Low and behold, over in the high grass, that was growing around a vacant building, the hose is discovered to have three kinks in it. Standpipes require a guage to be connected to it at the discharging valve, show the valve can be opened to the known operating pressure, and last if you are relaying water, simply ask the driver you are supplying water to what the residual pressure is on the forward unit. Keep it at 20 psi.

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    Quote Originally Posted by CALFFBOU View Post
    yep - I have a couple on order for when I get back and I downloaded an instructional thing.


    Thanks for the help guys
    I am a highly trained professional and can find my :: expletive deleted:: with either hand in various light conditions.

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    10 psi is too low for an 1 3/4 it should be 22-34 psi. the old standard in Illinois was 22 psi per 100' now it is even higher at 34psi.

    All you really need to know to run a pump is common sense and the ability to stay calmn under pressure. If you can get it in the ball park you will be fine. After that it is thumb up thumb down. Even if u know all the fancy formulas on a real fireground it still boils down to experience and getting it close. The main concern is being able to get water and maintain water. Know your apparatus and what can go wrong and how to fix it.

    The best thing I used to do is to laminate a cheat card that had friction losses on it and diff things like that. so when i did have to figure out a stretch I could reference that and get it close enough. If you use preconnects you should determine what to pump it at and know that.

    It is nice to know the science and formulas behind pumping, but you dont really need it on the street.

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    Before you can figure what the FL per 100 is you first have to know what your flow is. It is concievale that FL in 100 feet of 1 3/4 could be as low as 10-20 psi provded that the flow is 100-125 gpm range. at the same time it could be 35 psi (170 gpm) up to 50 psi (200 gpm) depending on tip size or flow rate.

    The following is true for 200 foot lays of 1 3/4 inch line with a 100 psi automatic fog nozzle. For flows of 150 gpm, 160 gpm and 170 gpm, your flow equals your PDP. In other words, what you pump (pressure) is what you get (flow)

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    Ya, that is one of the classes i', taking nowin fire science. Hydraulics for Firefighting edition2.....

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    If you use Task Force nozzles, they make a handy dandy slide chart that has it all for you.


    For a TFT 100psi automatic nozzle attached to 200' 1 3/4'' flowing 95 GPM the pump pressure needed to achieve 100psi nozzle pressure is 128psi.

    Flowing 125 GPM the pump pressure is 148psi to achieve 100psi nozzle pressure.


    They use the formula:

    PDP = NP + FL

    NP = nozzle pressure
    FL = friction loss
    FL = CQ2L (where the 2 is Q square)
    C = friction loss coefficient
    C for 1.5'' = 24
    C for 1.75'' = 15.5
    C for 2.5'' = 2
    Q = flow rate in hundreds of GPM
    L = length of hose in hundreds of feet

    You can easily determine how much water you are flowing and at what friction loss with this formula.

    I'll use our crosslays for example but I know this setup is VERY common. You can plug in any flow number (divide it by 100 per the formula along with the length of hose.) I'm going to use 115 GPM.

    200' 1.75'' with 100psi TFT nozzles

    NP = 100, C = 15.5, Q2 = 1.3225, L = 2

    PDP = (100psi) + (15.5 x 1.3225 x 2)

    PDP = 100psi + 40.9975

    PDP = 141 PSI to achieve 115 GPM through 200' of 1.75'' with TFT 100psi nozzle.


    So you can also conclude that the friction loss for this setup is 20.5psi per 100'

    Pretty easy.
    Last edited by Ha11igan; 02-05-2008 at 01:24 AM.

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    Here's an ancient formula,taught to me years ago.Small line FL 30# per hundred.Big hose 15#per hundred. 100Np fog 80Np Master stream 50Np straight bore.Now the hose FL's are high for modern hose but you'll always have plenty of water and it's easy to remember at O'dark thirty.No sliderule or firecalc required. T.C.

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    This site worked great for me.

    http://www.hydraulics4jakes.com/

    You can also find this finger method for 1.75"

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    I know it is extremly short notice..... Does anyone have a hydraulics worksheet that they use for classes? I am doing a class tonight and am looking to not completely recreate the wheel. Just looking for scenarios to give for hydraulic calculation practice. You can email me at jason@jbrescue.com. Thanks.
    Jason Brooks
    IAFF Local 2388
    IACOJ

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    A couple of things that will make it a little easier.

    1. Figure out all of your preconnects and simply commit the needed discharge pressure to memory.

    2. Standardize all preconnects on all apparatus so it will be the same.

    3. Figure out your GPM from your various smoothbore tip sizes and simply commit it to memory.

    If you do those three things, any calculations on a fireground will be very easy. If you figure out the friction loss ahead of time and commit it to memory, then it will cut down on the amount of calculating you have to do on the fireground.

    A cheat sheet on your apparatus (to be used for checking yourself) can be very helpful too and easy to make.

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    Quote Originally Posted by ChiefSquirrel View Post
    A couple of things that will make it a little easier.

    1. Figure out all of your preconnects and simply commit the needed discharge pressure to memory.

    2. Standardize all preconnects on all apparatus so it will be the same.

    3. Figure out your GPM from your various smoothbore tip sizes and simply commit it to memory.

    If you do those three things, any calculations on a fireground will be very easy. If you figure out the friction loss ahead of time and commit it to memory, then it will cut down on the amount of calculating you have to do on the fireground.

    A cheat sheet on your apparatus (to be used for checking yourself) can be very helpful too and easy to make.
    Thanks Chief,
    I have pretty much already done all of this for the class. I also have a cheat card that covers our normal and preconnect situations. I am looking to someones worksheet to force more thinking and confidence should the need arise that the lay changes.
    Jason Brooks
    IAFF Local 2388
    IACOJ

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    Pump operations is one of the things I teach the most. I find that nothing works as well as simply doing it over and over and over.......

    Create some scenarios and work through them - the confidence will come as the repetition builds your skills.

    After any calls you go on, try to put yourself in the pump operator's position and calculate what he had to calculate and then compare notes with him. This is a great way to build your skills, make sure his are sharp and learn based on a real situation.

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    I always go with this method, if the crew chief wants more he will ask if not than the 150psi i am giving him has either been good enough or he is making due with it and not needing anymore

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    Most engines run with preconnected lines which comes with set pressures based on the nozzle type, length of hose and expected gpm. So the solution is memorize those numbers.
    For UDC loads or dead loads where the length varies... know the friction loss per 100 ft and add it to the amount over the number you memorized from the preconnected lengths.
    Friction loss changes based on the gpm you are trying to flow. Know what your fire department wants to flow and base it on that. Not all fire departments use the same flows.
    If you know your nozzles pressures and you know your friction loss number then you can make your own cheat sheet.
    Here is an example: We have 200' x 1.75" with 150gpm fog tip preconnected line, my pump discharge pressure will be 170psi. That gives me 100 psi at the tip and 35 psi friction loss per 100 feet.
    If I were to put a smooth bore on the end I would subtract 50 psi because of the nozzle pressure difference so it would be 125 PDP
    Now you can figure the same for the 2.5 lines or whatever your department runs.

    Not knowing hydraulics is a problem but it only small portion of the problem.
    The biggest route of the problem in the fire service in general is not understanding the pump operators position or engineers position. Trouble shooting the pump has become a lost art with the implementation of pressure governors. Too often people think that the idle button is the answer to every problem without knowing what is happening to cause the problem. This is a very dangerous move for the people on the nozzle that lose pressure in a hostile environment. Another problem is understanding relay pumping. Volume and pressure concepts, pressure loses, hyrant pressures and volumes available need to be understood. You may have a 1250 pump but is the water system where you work going to be deliver that to you? What is it going to take to get that volume? How many gpm's are you going to need to put out the fire you are coming up to? What is your size up as a pump operator? Do you have enough water availlable if not where are you going to get it from? And what method can it be delivered?
    Sorry if I got off on a tangent but I have been seeing too many people becoming engineers that are not ready.
    IACOJ

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