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  1. #1
    MembersZone Subscriber Eno305's Avatar
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    Question Volume per length

    Hey guys...

    Just wondering if there was a general rule of thumb (I know there's a calculation but... you know... me and digits! Actually I could probably find it but looking for general rules) for calculating the amount of water needed to fill a hose line of certain diameter and length.

    The idea being that in my setting, often enough we need time to deploy defensive or transitional lines with pretty complicated layouts- with the protection of a line off the truck that may or may not end up tied in to a hydrant until later. Kind of complicated mix of manpower shortages and really exciting environment and hazards.

    So- anyways- trying to figure out with our 500 gallon tank... whether or not to use potentially longer protective lays with 1.75"... or shorter lays with 2.5"... and what the difference could be. We're big fire, big water mentality- but sometimes we don't want to throw the anchors out (tie in) on the truck right away.


    I've always got great information from folks in here- looking forward to some more.
    Ian "Eno" McLeod


  2. #2
    MembersZone Subscriber ffmedcbk1's Avatar
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    can you elaborate and give a specfic scenario. you post is confusing.

    as far as water in hose goes, 5" = 1 gallon a foot is the most basic one out there.

    technical answer :
    Volume = pie (3.142) * radius ^2 * h
    Height (or length for our purposes) and radius must be in same units, we’ll use inches

    5” hose
    Radius of 5” = 2.5”
    Length we are looking for is 12”
    3.142 * 2.5^2 * 12
    3.142 * 6.25* 12=235.65
    One gallon equals 231 cu inches, therefore it is slightly over 1 gallon per foot

    2.5” Hose
    3.141*1.25”^2*12=58.9125
    58.9125/231= 0.255 of a gallon



    a reference for you:http://www.mathopenref.com/cylindervolume.html
    Originally Posted by madden01
    "and everyone is encouraged to use Plain, Spelled Out English. I thought this was covered in NIMS training."

  3. #3
    Forum Member MemphisE34a's Avatar
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    Quote Originally Posted by Eno305 View Post
    So- anyways- trying to figure out with our 500 gallon tank... whether or not to use potentially longer protective lays with 1.75"... or shorter lays with 2.5"... and what the difference could be. We're big fire, big water mentality- but sometimes we don't want to throw the anchors out (tie in) on the truck right away.
    Although you got the technical answer to the question you were asking, I still don't think it's right. Not the answer given, but your question.

    The only two things that should determine your hose lay is:

    1. How close you can safely park to the incident without something falling on the apparatus or burning it up, and

    2. The amount of hose you have to lay from the engine to be able to make it to and work at the fire.

    The amount of water that you need at the fire determines the size hose you lay, not how far away it is.
    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.

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    ENO:

    FFMedic gave you part of the answer, and his examples help to illustrate what follows. Since the equation for calculating the volume of a cylinder (hose) contains Pi and length (toss them out), and also the volume of 5” per foot is almost exactly 1 gallon per foot, we can simply compare the square of 5” with the size of the hose we want to use for attack then divide the squares to determine how much hose can be filled with 1 gallon of water. 5” squared = 25 then if using 2 ½ - squared = 6.25 then dividing 25 by 6.25 we get 4 feet of 2 ½ filled by one gallon of water or 50 gal to fill 200’ of 2 ½” hose. For 2” the square is 4 and 25 / 4 = 6.25 feet or it will take 32 gallon to fill 200’ of 2” hose. 24.5 gal to fill 200’ of 1 Ύ, and 18 gal to fill 200’ of 1 ½” line.
    Kuh
    Last edited by KuhShise; 08-16-2009 at 10:55 PM.

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    MembersZone Subscriber ffmedcbk1's Avatar
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    The LT hit the nail on the head.

    What are you going to do if you don't meet and exceed the fire flow for the incident?

    You can flow water @ 50 gpm for 10 minutes or you can use that 500 gallons (we don't know your other supply varibles) in the best manner possible by many methods of attack. Still need some more info to help out more.
    Originally Posted by madden01
    "and everyone is encouraged to use Plain, Spelled Out English. I thought this was covered in NIMS training."

  6. #6
    MembersZone Subscriber ffmedcbk1's Avatar
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    Quote Originally Posted by KuhShise View Post
    ENO:

    FFMedic gave you part of the answer, and his examples help to illustrate what follows. Since the equation for calculating the volume of a cylinder (hose) contains Pi and length (toss them out), and also the volume of 5” per foot is almost exactly 1 gallon per foot, we can simply compare the square of 5” with the size of the hose we want to use for attack then divide the squares to determine how much hose can be filled with 1 gallon of water. 5” squared = 25 then if using 2 ½ - squared = 6.25 then dividing 25 by 6.25 we get 4 feet of 2 ½ filled by one gallon of water or 50 gal to fill 200’ of 2 ½” hose. For 2” the square is 4 and 25 / 4 = 6.25 feet or it will take 32 gallon to fill 200’ of 2” hose. 24.5 gal to fill 200’ of 1 Ύ, and 18 gal to fill 200’ of 1 ½” line.
    Kuh

    hey, thanks for that nugget. it didn't even occur to me to think of in square roots.
    Originally Posted by madden01
    "and everyone is encouraged to use Plain, Spelled Out English. I thought this was covered in NIMS training."

  7. #7
    MembersZone Subscriber Eno305's Avatar
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    Thumbs up

    I can honestly say that is the first time I got told that I got the wrong question. Certainly not the first time I'd been told I got the wrong answer lol! By Kuh, a few times, I figure!

    In a conventional set of circumstances, I wholeheartedly agree with what you're saying LT. Of course, I suppose I forgot to mention that I work in a rather unconventional environment and have unconvential requirements and access to unconventional assets.

    In our environment during these "unconventional" circumstances- it is in fact the water system that acts as our Engine, and the Engine is actually just a tool shed with water and foam sloshing around in the back. The truck's main task is deploying the troops to rig up our water system with on board appliances and hose. It remains a dynamic asset to be deployed as necessary later in the call. Our first jump off point may not be where we need to unmask the 5000gpm deck howitzer on the roof, or fully benefit from the husky 300 foam system in its belly. No sense getting it buried by 5" before we even put it where it belongs.

    Through training we're adopting tactics that involve plugging smaller diameter hoses (2.5"- hopefully 3" soon!) into the truck to supply protective lines quickly. When disconnected, those lines can then be redeployed with ground based monitors- either Blitzfires or Crossfires... or a 2.5 handline nozzle. We're finding more diversity and flexibility in temporarily supplying with 2.5" (for our initial protective deployments) and saving the anchors (5") for when we know where we're actually going to need to stage the truck.


    We're finding through our own experience that priority is in getting fixed ground monitors going (from farthest to closest), then rigging our portable ground monitors off of hydrants, then establishing our work area and at that point connecting the truck where necessary and utilizing foam, the deck howitzer, or maneuvering attack lines as necessary to isolate problems.

    As usual, we operate under the same basic principals as everyone else- weighing our risks against the benefits. In a rescue situation, we'll deploy differently than if a heater is on fire with a half a dozen safety guys hanging around to watch. Guys mock those of us in industry, but our hearts are in the right spot.

    But unlike many other departments- we've got 1 engine available immediately and our nearest backup is half an hour away. Over 100 000bbls/d of hydrocarbons to add to equation and all the pleasantness of the process to go along with it.

    Also, we've got 8 folks MAX heading to the call... before the auxiliary members show up (10-30 minutes) So we've had to adopt tactics that accommodate our restrictions. Fortunately, we have a water system that can flow well over 8000gpm out of one manifold and keep 50psi on the compound. Our water mains are 42" and even the feeders are 12-16". So the water system is a great force multiplier... But a hydrant needs to be dressed- and in some cases the guys doing the dressing need to be protected. And sometimes the safety guys are hanging out. Sometimes, the hydrants are in unprotected areas... and the guys dressing them need some coverage... for safety... ya know? Enter the question.


    I didn't in fact ask the wrong question, LT, but as you suggest I may eventually conclude (as a result of asking the RIGHT question and subsequent answers) that the restrictions of our tank and the requirements of the situation might exceed practicality.

    What inspired this specific question was a crew went to an area without a hydrant and wanted to do a quick test on a standpipe... subsequently (and surprisingly it seems) draining most of the tank. I wanted to give folks around here a general idea (respect) to how much water is going to disappear JUST from charging a line.

    I know even on the conventional side, pump operators have priority in getting water to attack lines, and then hooking up supply. Often they (sorry, WE) dodled a bit- not appreciating that filling those hoses would drain half our tank. Or at least not knowing how much of that water was going to disappear...

    Anyways- on top of applied curiosity... I have this little voice in my head saying that at some point- having a little spreadsheet on it wouldn't hurt... so wrong question or not I have satiated that little voice with help from all of you.

    And LT, I appreciate the scrutiny... though I do maintain I was asking the right question.
    Last edited by Eno305; 08-17-2009 at 07:30 AM.
    Ian "Eno" McLeod

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    Can someone refresh me on the details of the term "square to compare" with regard to capacity of hoses flowing water.

    Thanks

  9. #9
    Forum Member MemphisE34a's Avatar
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    Quote Originally Posted by Eno305 View Post
    And LT, I appreciate the scrutiny... though I do maintain I was asking the right question.
    Not scrutiny brother, just food for thought!
    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.

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