Thread: friction loss

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    Default friction loss

    Can anyone tell me the friction loss of different size hoses. The batallion chief at our VFD told us numbers a few of us thought were off. We didn't argue because he is our BC, but I would like to know so I do it right.
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    I could, but it would be in metric terms and might confuse you...
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    Although there is a calculation to give an estimate to friction loss, each hose will be slightly different due to imperfections, wear, damage, manufacturer, etc. Your battalion chief is likely quoting the standard accepted for your department for use on the fireground. You should accept the numbers as such but you should ask him to clarify this.

    We use the following:

    1" - 60 psi per 100'
    1.75" - 35
    2.5" - 15
    4" - 10
    5" - 10

    Are these exact? Of course not. These are simply what we use on the fireground. Only testing each individual hose will give you the exact amount.

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    20 psi per length of 1.75 (50 ft)
    5 psi for 2.5

    5 psi for each floor above grade
    90 psi for a fog nozzle and 50 for a 15/16 smooth bore and 40 for an 1 1/8.

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    Quote Originally Posted by tnff320 View Post
    Can anyone tell me the friction loss of different size hoses. The batallion chief at our VFD told us numbers a few of us thought were off. We didn't argue because he is our BC, but I would like to know so I do it right.
    I can't tell you the individual amount of friction loss for your hoselays because I don't know how long they are or what amount of GPMs you're trying to flow.
    But here are the generally accepted coefficients for common hose sizes...

    " booster: 1,100
    1" booster: 150
    1" rubber lined hose: 24
    1" rubber lined w/1" couplings: 15.5
    2" hose: 2
    3" hose w/2" couplings: 0.8
    4" hose: 0.2
    5" hose: 0.08

    Plug these into the FL = CxQxQxL formula (writing it that way was easier than trying to set up the superscript for Q squared) along with the values for Q and L, and you'll have your answer.
    Q: quantity of GPMs being delivered, divided by 100
    L: length of hose lay in feet, divided by 100

    And don't forget to make adjustments on the fireground for elevation changes and in-line appliances.

    Hope this helps.

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    Quote Originally Posted by ranahan View Post
    I can't tell you the individual amount of friction loss for your hoselays because I don't know how long they are or what amount of GPMs you're trying to flow.
    But here are the generally accepted coefficients for common hose sizes...

    " booster: 1,100
    1" booster: 150
    1" rubber lined hose: 24
    1" rubber lined w/1" couplings: 15.5
    2" hose: 2
    3" hose w/2" couplings: 0.8
    4" hose: 0.2
    5" hose: 0.08

    Plug these into the FL = CxQxQxL formula (writing it that way was easier than trying to set up the superscript for Q squared) along with the values for Q and L, and you'll have your answer.
    Q: quantity of GPMs being delivered, divided by 100
    L: length of hose lay in feet, divided by 100

    And don't forget to make adjustments on the fireground for elevation changes and in-line appliances.

    Hope this helps.
    That is the only way to figure it correctly as friction loss is on a HUGE sliding scale. Regardless of the size of hose, the more you try to pump through it, the more friction loss you will have regardless of length. For example, there is more FL is 100' of 1 3/4" hose flowing 200 gpm than the same line flowing 80 gpm. The only way to make a blanket "this hose has this much FL" is to qualify it with the amount of gpm you are pumping at the time. This is why the last 3 guys in a row all listed the FL for 1 3/4" hose different ranging from 15.5 to 35. They did similar with the 2 1/2".

    They most likely all use different nozzles or pressures designed to deliver gpm's specific to their departments making them all correct, but only for their specific department.
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    Comments made are my own. They do not represent the official position or opinion of the Fire Department or the City for which I am employed. In fact, they are normally exactly the opposite.

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    Get the IFSTA book and use that. I think the factors are in both the Driver operator and fire streams books.

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    Here is some numbers that you can use...may not be exact for all layouts but pretty darn close.

    1 3/4 line flowing 150 gpm = 35 psi FL per 100 ft of hose.
    ........................175..........47
    ........................200..........62


    2 1/2 line flowing 200 gpm = 8 psi FL per 100 ft of hose.
    ........................250..........13
    ........................300..........18
    ........................350..........25


    5" line flowing 1000 gpm = 8 psi FL per 100 ft of hose.
    ....................1500.........18
    ....................2000.........32

    Add 5 psi per floor above ground.
    Last edited by FIRECAPT62; 07-02-2008 at 11:02 AM.

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    According to the TFT slide chart for a 100PSI nozzle:

    200' of 1.75''
    60 GPM = 111 PSI pump pressure
    95 GPM = 128 PSI pump pressure
    125 GPM = 148 PSI pump pressure
    150 GPM = 170 PSI pump pressure
    175 GPM = 195 PSI pump pressure
    200 GPM = 224 PSI pump pressure
    225 GPM = 257 PSI
    250 GPM = 294 PSI


    200' of 2.5''
    60 GPM = 101 PSI
    95 GPM = 104 PSI
    125 GPM = 106 PSI
    150 GPM = 109 PSI
    175 GPM = 110 PSI
    200 GPM = 116 PSI
    225 GPM = 120 PSI
    250 GPM = 125 PSI
    275 GPM = 130 PSI
    300 GPM = 136 PSI
    325 GPM = 142 PSI
    350 GPM = 149 PSI


    If you use TFT nozzles this chart is great for knowing exactly how much water you are flowing through their automatic nozzles.
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    You are doubting what your BC told you?? You won't last long in this profession.

    Get a hydraulic manual and look it up. It all varies with the size and shape of the nozzle, hose and how much pressure the pump operator is trying pump or lack thereof.

    Here check this out.

    http://www.elkhartbrass.com/files/aa...log-e-T-09.pdf
    Last edited by Jonnee; 07-01-2008 at 04:39 PM.

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    Quote Originally Posted by Jonnee View Post
    You are doubting what your BC told you?? You won't last long in this profession.
    I am curious to hear the rationale behind this one. Some of the most incompetent people I have seen are Chiefs. I suspect its not much different from place to place.
    Last edited by MemphisE34a; 07-01-2008 at 10:04 PM.
    RK
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    Management is making sure things are done right. Leadership is doing the right thing. The fire service needs alot more leaders and a lot less managers.

    "Everyone goes home" is the mantra for the pussification of the modern, American fire service.


    Comments made are my own. They do not represent the official position or opinion of the Fire Department or the City for which I am employed. In fact, they are normally exactly the opposite.

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    Quote Originally Posted by MemphisE34a View Post
    I am curious to here the rationale behind this one. Some of the most incompetent people I have seen are Chiefs. I suspect its not much different from place to place.
    I second the motion.

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    Quote Originally Posted by Ha11igan View Post
    According to the TFT slide chart for a 100PSI nozzle:

    200' of 1.75''
    60 GPM = 111 PSI pump pressure
    95 GPM = 128 PSI pump pressure
    125 GPM = 148 PSI pump pressure
    150 GPM = 170 PSI pump pressure
    175 GPM = 195 PSI pump pressure
    200 GPM = 224 PSI pump pressure
    225 GPM = 257 PSI
    250 GPM = 294 PSI


    200' of 2.5''
    60 GPM = 101 PSI
    95 GPM = 104 PSI
    125 GPM = 106 PSI
    150 GPM = 109 PSI
    175 GPM = 110 PSI
    200 GPM = 116 PSI
    225 GPM = 120 PSI
    250 GPM = 125 PSI
    275 GPM = 130 PSI
    300 GPM = 136 PSI
    325 GPM = 142 PSI
    350 GPM = 149 PSI


    If you use TFT nozzles this chart is great for knowing exactly how much water you are flowing through their automatic nozzles.
    "Exactly" is not a word any of us can use when unless you properly test the exact layout. There are too many factors to be single digit accurate on the sliding rule chart or any rule of friction loss. Hose differs greatly, discharge piping differs greatly, accuracy of gauges differs, given these factors I'd sat exact or even "close" is a stretch. You want to know, get out and test the hose/nozzle set up on your apparatus.

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    Ancient formula given to me in the formative years by a very good fire instructor.Based on OLD hose construction so not too accurate today but if you apply it you'll always have sufficent water.Only good for 1.5 thru 3". 30# per 100' SMALL hose(up to 2").15# per 100' Big hose (2"up). Easy to remember at O'dark thirty.The Q formula,while quite accurate, is a bit harder to remember,In fact the only Q formula I remember at 2am is 2Q+2Q(4rkQ).Turn up the throttle 'til the nozzleman lifts and cut it back twenty.LDH 5-10 per 100' will give you good flows for most lays.Again,overkill but would you rather be a tiny bit short or a bit over? I'll opt for having a little reserve.If you're looking for accuracy,get a cheatsheet and a calculator. Good luck,T.C.

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    1.75" hose (Q*Q)/5
    1.5" hose (Q*Q)/3
    2.5" hose Q-10

    Q= GPM with last digit dropped, ex: 125gpm Q=12

    These will get you close to the IFSTA calculations. Each unit of friction loss is per 100' of hose. Don't forget to add +/- for each floor of elevation. Don't forget to add for appliances, wyes or siameses...etc.
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    It depends largely on the brand of hose you're using.

    My dept uses outdated numbers from the 60's, and in turn, we end up over pumping our nozzles.

    I would take Elkhart Brass' opinion before your BC's. But even this isn't 100% accurate.

    Elkhart Brass Friction Loss Chart
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    Ask 10 pump operators and get 10 different answers.......

    You'll find that most people are in the same ball park. We just take a different path to get there. It all boils down to how you can remember it at 0-dark thirty in the morning. Some people over complicate it and some underestimate their importance.

    In my simple mind, I had everything broken down per length (Assuming 50')

    1 3/4" @150gpm = 20/length
    1 3/4" @185 gpm = 25/length (for those of us using 15/16" smoothbore)
    2 1/2" w/ 1" tip = 5/length
    2 1/2" w/ 1 1/8" tip = 7.5/length
    2 1/2" w/ 1 1/4" tip = 10/length
    5" @ 1000 gpm = 10/length (100ft)

    You also have to know your pre-connect pressures.

    They're all approximate numbers. Remember- a difference of 5-10 lbs at the pump is only 2 or 3 lbs at the tip.

    Use any method that is accurate and easy to remember. Good luck.
    Last edited by jplas577; 07-16-2008 at 02:36 PM.

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    This is a great question, and one that I feel most new people will ask themselves at some point in their learning careers. When I was on our training committee, we were tasked with looking at new nozzles. One of my suggestions was that we take in line pressure guages and flow meters out to the tower, and see if our "old" FL tables were accurate. Of course that was too much work, and may have caused controversy over our accepted tables that had been weathered to a dirty brownish/yellow. So with that spirit, I will offer what we have been taught, and still live by in my neck of the woods.
    For 1 3/4 with a 100 psi fog nozzle:
    125 gpm = 18 psi
    150 gpm = 27 psi
    175 gpm = 36 psi
    200 gpm = 45 psi
    250 gpm = 70 psi

    For 2 1/2" hose we used the following table:
    tip size f/l(psi) np gpm
    3/4" 3-4 50 100
    7/8" 7-8 50 150
    fog 7-8 100 150
    1" 10 50 200
    1 1/8" 18 50 250
    fog 18 100 250
    1 1/4 25 50 300


    So if you use this table for 2 1/2" hose, it does not matter what the nozzle is per se, it just means that for a given flow, the friction loss is x. We used the nozzle tip sizes to aid in remembering the FL. As you can see 3/4" is 3-4, the 1" tip we remember as 1 so add a zero. 1 1/8, look at the 1/8 for 18 psi and 1 1/4 look at 1/4 and think of 25 as in a quarter is 25 cents. Bear in mind we have relics for 2 1/2 fog nozzles, and currently only have 250 gpm nozzles for fog selection, and actually only carry the 1" and 1 1/8" or 1 1/4" smooth bore, depending which engine you are on.

    Our master stream table was broken down as follows:

    # of 2 1/2 lines tip size f/l flow
    2 1 1/4 10 400
    2 fog 18 500
    2 1 1/2 25 600
    3 1 1/2 10 600
    3 1 3/4 18 800
    3 2 25 1,000

    Here again you see a pattern.

    For our 3" hose we used Q2. Q being the gpm divided by 100.

    This has worked for us so far, but again I would love to actually put these numbers to the test. With our new chief, and now being on a new committee that will research this, I am hoping to prove or disprove these numbers. It makes no difference to me, I would just like to know if we are close or not.

    Not sure if this helps you at all, but thought I would answer your question.

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    Quote Originally Posted by Jonnee View Post
    This is the best free copy you'll likely find.

    Friction Loss varies a little with each type of hose. And some vary with pressure because the hose may stretch some at higher pressures.
    The American people will never knowingly adopt Socialism. But under the name of 'liberalism' they will adopt every fragment of the Socialist program, until one day America will be a Socialist nation, without knowing how it happened. --Norman Mattoon Thomas, 6 time presidential candidate for the Socialist Party of America

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    Default Pgfd

    In PG County, MD we use Q formulas. Q = quantity(gpm).

    1-1/2" hose(2Q squared X 25)
    1-3/4" hose(2Q squared X 12)
    2" hose(2Q squared X 6)
    2-1/2" hose(2Q squared)

    3" supply (2Q squared X .33)
    PGFD

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    Quote Originally Posted by Ha11igan View Post
    According to the TFT slide chart for a 100PSI nozzle:

    200' of 1.75''
    60 GPM = 111 PSI pump pressure
    95 GPM = 128 PSI pump pressure
    125 GPM = 148 PSI pump pressure
    150 GPM = 170 PSI pump pressure
    175 GPM = 195 PSI pump pressure
    200 GPM = 224 PSI pump pressure
    225 GPM = 257 PSI
    250 GPM = 294 PSI


    200' of 2.5''
    60 GPM = 101 PSI
    95 GPM = 104 PSI
    125 GPM = 106 PSI
    150 GPM = 109 PSI
    175 GPM = 110 PSI
    200 GPM = 116 PSI
    225 GPM = 120 PSI
    250 GPM = 125 PSI
    275 GPM = 130 PSI
    300 GPM = 136 PSI
    325 GPM = 142 PSI
    350 GPM = 149 PSI


    If you use TFT nozzles this chart is great for knowing exactly how much water you are flowing through their automatic nozzles.

    That is of course if you send in your automatic nozzles for maintenence once a year and pay $130+ per nozzle (please let me know if you can get it cheaper). I used to be a big fan of automiatic nozzles until we ran some tests on them (several of the same nozzle, different stations) and found that we were flowing anywhere from 125 to 195 GPM while flowing at the same rate (215psi engine pressure, 200' lay, looking for 175 GPM from the nozzle). That chart is a good reference guide but you are assuming that the nozzle and spring inside the nozzle are in perfect working condition. That is rarely the case. In all honesty, most of us assume we are flowing the said amount of H2O but if you were to put the pressure gauges to the equipment, most would find that they are flowing less than they thought. We made the switch the fixed gallonage nozzles (Elkhart) and couldnt be happier. No maintenece is required so in camparison to the automatic nozzle, the fixed gallonage nozzle pays for itself in 5-6 years. Sorry to get off subject but figured I would share my feelings towards automatics...

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