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  1. #1
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    Default Siamese Connections

    111111111111111
    Last edited by emsff32515; 03-12-2008 at 12:14 PM.


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    A useful application is two 2-1/2" from a hydrant or pumper (pumper that has no LDH discharge) to fill a 5" Storz/LDH

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    one situation here is for a "heavy water hook up"

    sometimes the engine will use the front sleeve 4" line and hook up to the steamer cap(4 1/2").

    they'll than put a 2 1/2" to 4"(stortz coupling) on each but of the hydrant. They'll than run the lines off of the butts to a siamese, and a 4" line off of that to the intake in the engine to increase its intake.

    another use is for when two engines are pumping to an tower/ladder/truck for defensive operations. If they have to pump a long ways they'll run 2 lines into the siamese and than 1 into the truck.
    Last edited by somebody509; 02-22-2008 at 10:23 AM.

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    When we pull our deck gun off the engine to make it a ground monitor, we use a siamese to connect 2 2 1/2" Hoses for enough flow.

    Of course, outside of training, we've done it once in the past 3 years.

    We just got our first Blitzfire ground monitor, so we may never do it again either. But it does make for a good drill that makes the engineers think.

  5. #5
    Forum Member MemphisE34a's Avatar
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    The siamese adapter was popular long before the advent of LDH.

    The siamese therefore allowed for longer lays with a greater volume of water to a specific appliance while also lowering the total pump discharge pressure (PDP).

    Using the deckgun scenario in one of the posts above for instance: A single 2 1/2" hose line will not flow 1000 gpm without an outrageous PDP and even so, only for about 100' or less. Splitting the volume by pumping it into multiple lines reduces friction loss so you can lay farther and also lowers the PDP, but gets the same amount of water to the appliance when you bring it all back together - normally in a larger diameter opening than the individual lines suppling it.

    They are most common around here while pumping to some of our older aerials. Two 2 1/2" to the siamese and a 3 1/2" up the stick.
    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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    Default

    111111111111111111111111111111 11
    Last edited by emsff32515; 03-12-2008 at 12:23 PM.

  7. #7
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    Default Water Supply

    We use them in our rural water supply rather then using portable ponds. We tie the first tanker into the attack engine and use it as a nurse. The tanker has a short length of LDH followed by a siamese then a short length of LDH coming off both sides. This way you can have one truck off loading and the next one hooked up and ready to go.

    OK i know there are rural water supply guys out there freaking out because we are no using our ponds and tieing up a tanker. Yes there are pros and cons and they have to be weighted. Pros - no drafting on scene, in winter you have less water on the ground, no backing to use quick dumps (everyone has side pump discharges).

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    Quote Originally Posted by emsff32515 View Post
    Thanks for the input - So my interpretation is that if we were to need to lay in 400' rather than using 2 1/2" the entire way, we would use 2 - 1 3/4" lines say 200 or 300 feet to a simaese, then continue with a 2 1/2" into the house????? So basically it is for distances....But would you use both of the 1 3/4" from the same engine?
    I'm not sure if I'm understanding what you are saying, but.........

    The siamese isn't "basically... for distances". It's used for merging seperate water supplies together. In today's operation, there's probably little use for a siamese outside of merging a pair of 2-1/2 or 3" lines into LDH or a monitor or the FDC on a building. The siamese tends to be more of a supply appliance.

    What you appear to be describing sounds like a long stretch for fire attack??? If that's the case, then I can't think of any reason to stretch 2 1-3/4" lines and then try to merge them into a 2-1/2" line for fire attack. If you need the 2-1/2 at the fire, then stretch a 2-1/2.

  9. #9
    Forum Member volfirie's Avatar
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    We 'twin' (siamese) lines for a feed if there's a long run to the nearest hydrant, or if we have a really long run and have to use muliple pumpers to boost from the supply to the attack pumper(s). Our hydrants are 2 1/2 inch, so thats what we run as twins. Purely to reduce friction loss.
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    Like some people have said, they were more usefull unitl the implementation of LDH. Now I have have only ever seen them used to flow elevated master streams (ladder pipes) and portible monitors. But with the Blizfires and Mercury nozzle type monitors in the field now flowing off of one 3" line, siameses for them are now some what out dated. In addition to that more monitiors can be supplied with either 4" or 5" inch LDH. But to get back to siameses, other than supplying ladder pipes, we really only use a 4" inch gated siamese when running a box in a non-hydrated area. This alows the next in (typically third due in our dept) engine to supply the siamese to the scene while setting up the dump site. It also allows the tankers to come in behind them and supply the scene if the dump site is not operational yet or the engine company has problems with it's pump.
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  11. #11
    Forum Member MemphisE34a's Avatar
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    Quote Originally Posted by emsff32515 View Post
    Thanks for the input - So my interpretation is that if we were to need to lay in 400' rather than using 2 1/2" the entire way, we would use 2 - 1 3/4" lines say 200 or 300 feet to a simaese, then continue with a 2 1/2" into the house????? So basically it is for distances....But would you use both of the 1 3/4" from the same engine?
    I guess your right in theory, but you would never do that!! Get out a basic firefighting or pumping apparatus book and read it.
    RK
    cell #901-494-9437

    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.

  12. #12
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    Quote Originally Posted by emsff32515 View Post
    Thanks for the input - So my interpretation is that if we were to need to lay in 400' rather than using 2 1/2" the entire way, we would use 2 - 1 3/4" lines say 200 or 300 feet to a simaese, then continue with a 2 1/2" into the house????? So basically it is for distances....But would you use both of the 1 3/4" from the same engine?
    Ummm, NO. The PDP on the 1 3/4" lines would be rather high based on your desired flow. Remember your coefficients for an 1 3/4" line C=15.5 and for a 2 1/2" C=2. In your layout using the 2 1/2" alone would be better than dual 1 3/4" lines.

    From Houston FD Training:

    Example 1: If 200 gpm is flowing from a nozzle, what is the friction loss in 200 ft. of 2Ĺ" hose?

    FL = C∑Q≤∑L
    C = 2
    Q = gpm/100 = 200/100 = 2
    L = length/100 = 200/100 = 2

    FL = (2) (2)2 (2)
    FL = (2) (4) (2)
    FL = (8) (2)
    FL = 16 psi

    Note: FL is the total friction loss

    Example 2: If 150 gpm is flowing through 200 ft. of 1ĺ" hose, what is the friction loss from the hose?

    FL = C∑Q≤∑L
    C = 15.5
    Q = gpm/100 = 150/100 = 1.5
    L = length/100 = 200/100 = 2


    FL = (15.5) (1.5)2 (2)
    FL = (15.5) (2.25) (2)
    FL = (34.875) (2)
    FL = 69.75 psi (round to 70 psi)

    Same lengths of hose in each example but with different flows and much different friction losses.

    Hope this helps.

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