Why register? ...To Enhance Your Experience
+ Reply to Thread
Results 1 to 9 of 9
  1. #1
    Forum Member
    Join Date
    Jun 2005
    Posts
    19

    Default Need Help w/ best way to test hydrant set-up

    My dept rarely uses hydrants, but when called for mutual aide we do.

    Someone came up with the great idea that more water could be flowed through 2-2 1/2 pony hoses, with one of them having a valve at the hydrant, to a clappered Y connected to the 5" LDH.

    I wont go into it now, but for the purpose of this discussion steamers dont exist.

    My question is how to best prove that just using the(1) 2 1/2 to Stortz fitting will flow more water.

    Should I use a higher or lower flowing hydrant for the comparisions? Does it matter?

    How much LDH should I use?

    Thanks for the help and if I need to clarify let me know.


  2. #2
    Forum Member Fire304's Avatar
    Join Date
    Jun 2002
    Location
    At the Helm
    Posts
    1,174

    Default

    Good question...

    I think you'll have to prove it with a flow test.

    First off, you need to know how much volume your hydrants are capable of, do you have big modern pipes or 200 year old cast iron that collapses every time you flow more than 50gpm? This will determine the tip you're gonna use on the end of the 5".

    I'd set up my test with enough 5" to give a realistic lay, in my area 300' might be appropriate (plugs are 500' apart) but not so long that friction from the LDH becomes a factor. Set up a deluge gun with a tip that will flow the hydrant's capacity directly to the end of the 5". You'll need a pitot and a flow chart for your tip. Set up the direct feed and let it flow until you get a steady reading at the tip (might be a minute or more). Add in the wye feed and do it again. Everything should be the same between the two runs, just the addition of the wye feeder should change. Its important that the narrowest spot be the feed so a choke point down the line does not dampen the results of the test. If you don't have a 5" deluge gun be sure to use either two 3" feeders or three 2 1/2" feeders to your gun, preferable three 3" to minimize friction loss there.

    My hunch is that a high flow hydrant would prove your point better as friction loss would be more of an issue. Two 2 1/2 feeders won't flow much beyond 1000gpm even if they are really short, so there's your first limitation. At 500gpm each you'll get 11psi loss on 20' section. Your wye should give you 15psi loss, that's 26psi vs. almost none for the stortz adaptor (all the loss will be in the hydrant, something that you can't modify).

    The ultimate rig would be two 5" feeders to a wye, or even better a double 5" lay from the plug to the pump. Virtually no friction loss added that way. Problem is, if your hydrants will only flow 500gpm its all moot, you'll probably see very little difference between the two rigs.

    Hope that helps
    ______________________________ __________________
    If you are new to posting please CLICK HERE for an essential lesson
    ______________________________ __________________
    A bad day in the boat is better than a good day in the office. And in my case the office is a boat!

    IACOJ Fire Boat 1

  3. #3
    Forum Member
    Join Date
    Jul 2005
    Posts
    956

    Default

    2 2-1/2's will never flow more that 5". Yes I said never... The easiest way that I can thnk to do it is use a dump tank of a certain size, say 3000gal. Find a level surface. Find a hydrant, figure out what your outlet pressure is. THEN hook up your 5", and flow it into the dump tank, while timing how long it takes to fill, then repeat with the 2-1/2. Use 200ft.
    FF/NREMT-B

    FTM-PTB!!

    Brass does not equal brains.

    Courage is not the absence of fear, but rather the ability to control it.

  4. #4
    Forum Member
    Join Date
    Jul 2004
    Location
    Penn Valley, Ca
    Posts
    571

    Default

    Here is the simplest way. It will not give you any hard numbers but it will tell you that "this is better than that." Simply set up your deck gun with, say, a 1-3/4" tip on it (any tip that flows a lot of water) with its control valve wide open and the pump discharge at, say 100 psi. Then read and record the pump intake pressure. Now change to the other setup and duplicate the discharge conditions. Pump discharge at 100, same size tip, valve wide open. Then record the pump intake pressure. Higer intake = lower friction loss = more GPM available = better method.

    Birken

  5. #5
    Forum Member
    Join Date
    Jun 2005
    Posts
    19

    Default

    Thanks alot guys.

    I new it would be simple, I was just looking for the elements, such as the length of the LDH lay, that would exacerbate the differences between the two set-ups.

    I do have a pitot, so when I get around to it I will post both the preasure loss and GPM differences.

    Thanks again.

  6. #6
    Forum Member
    Join Date
    Jul 2004
    Location
    Penn Valley, Ca
    Posts
    571

    Default

    There should be no GPM difference. To run a scientific test you need to change only ONE thing at a time. In that case that ONE thing would be the intake layout. The same discharge pressure to the same size smoothbore will result in the same GPM and that is how it needs to be.

    The length of the LDH lay should not be a big factor as the system either way is going to have a serious "choke point" and that is either the 2-1/2" restriction from the hydrant or the two 2-1/2" hoses. The loss from other factors will be very low by comparison.

    Have you seen this thread? In it the same layout you are discussing was tested, except another LDH was taken from the steamer port at the same time, for a dual LDH lay. However the extra steamer should be immaterial. The result was, as expected, the LDH fed through an adapter from a single 2-1/2" port had the lowest FL. Lots of pictures there if you click on the links.

    Birken
    Last edited by BirkenVogt; 10-13-2005 at 01:45 PM.

  7. #7
    Forum Member Fire304's Avatar
    Join Date
    Jun 2002
    Location
    At the Helm
    Posts
    1,174

    Default

    Birken, my only concern with your method is that it will require a very sensitive and calibrated intake gauge to detect a 20psi difference (which I think is all you'll see at 1000gpm, if this setup only flows 500gpm you'll have less than 10psi). Almost every truck I've ever seen the intake/discharge gauges don't agree and trying to see a 10psi difference between two setups, well you'll see 10psi, but you won't be able to tell if its 7 or 13psi.

    If you remove the pump and feed directly to a smoothbore deluge set you'll be able to use a pitot which is a sensitive and calibrated gauge. The only trick is to insure your smoothbore is big enough to produce flows which will challenge the hydrant setup, which could be accomplished by having a desire nozzle pressure of say 40-60psi below the hydrant pressure (desired tip pressure should be 40-50psi, any lower and you're off the smooth bore flow chart).

    Ok, having absorbed all that's been posted here's my revised setup.

    1st; determine you hydrant static pressure. You'll need a 2 1/2 cap with a pressure gauge on it or hook up the truck to it with the pump out of gear and read the intake with no water flowing. Does not have to be super accurate, within 10-20psi is fine.

    2nd; with the direct connection on (I'm assuming this will be the better flowing of the two) and 20-100feet of 5", begin flowing through various tip sizes, checking the pressure with your pitot until you get a tip pressure of at least 20-40psi below the hydrant. Record your tip pressure and determine what the flow rate it.

    3rd; switch over to the wye setup and with the same tip flow and pitot.

    My bet would be a 10-20psi drop for the wye, which you'll be able to calculate a significant difference in gpms for. At worse they'll flow about the same and you can use the argument that taking the extra time and equipment to set up the wye just isn't worth it.

    I also think you'll show a better result with a hydrant that's got enough flow to use a big smooth bore, but not so much that you'll be up in the 60+psi range on the pitot with your biggest smoothie.

    Good luck.
    ______________________________ __________________
    If you are new to posting please CLICK HERE for an essential lesson
    ______________________________ __________________
    A bad day in the boat is better than a good day in the office. And in my case the office is a boat!

    IACOJ Fire Boat 1

  8. #8
    Forum Member
    Join Date
    Nov 2004
    Posts
    710

    Default

    We were discussing a similar issue about hydrants in this thread - http://forums.firehouse.com/showthread.php?t=74402 - It has some pictures of different hydrant hookups that we tried and found ways to get more water.

    The siamese into the clapper actually for some reason flows less water - I can only explain this through friction loss. In that thread we tried several set ups, have a look.
    -I have learned people will forget what you said,
    -People will forget what you did,
    -But people will never forget how you made them feel!

  9. #9
    Forum Member confire's Avatar
    Join Date
    Jan 2005
    Location
    Northern Indiana
    Posts
    328

    Default

    Driver, If I understand your question you basically want to know what flows more water, the 5” connected to a 2.50 hydrant port or two short 2.50 lines from both 2.50 two ports siamesed into the 5”. If indeed that is what your are asking, we also wondered the same thing a few years back.
    I had to look for a bit but found the report.

    Forward lay of 1000 feet of 5” hose to a 1500 GPM engine. Engine residual pressure of 5 PSI

    Test-1 One 5” line connected directly to a 2.50” port.
    Results: Hydrant: residual 55 PSI @ 810 GPM flow

    Test-2 Two 25 foot 3” lines from two 2.50” ports siamesed into a the 5” hose.
    Results: Hydrant: residual 55 PSI @ 810 GPM flow


    We were surprised that the flow was the same that we checked it twice.
    Remember lots of friction loss in the two 3” lines, and the Siamese

    I hope that helps.

Thread Information

Users Browsing this Thread

There are currently 1 users browsing this thread. (0 members and 1 guests)

Similar Threads

  1. Test Anxiety
    By dmfireschool in forum Hiring & Employment Discussion
    Replies: 0
    Last Post: 10-11-2003, 03:39 PM
  2. Finding ISO Department Data
    By 640SATFD in forum Apparatus Innovation
    Replies: 12
    Last Post: 03-11-2003, 12:05 AM
  3. Thermal Imaging SOG's
    By wtfd92 in forum Firefighters Forum
    Replies: 23
    Last Post: 06-27-2001, 08:41 PM

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts