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Pumps in Farm Machinery March 09, 2011, 05:44:08 PM
Just installed a 10hp Diesel Pump that I bought online down at the dam, it has a 4" intake and I have reduced the out from 4" to 1 1/4  the pressure is amazing at the pump but after I connect the rest of the 1 1/4 aggie pipe the pressure at the end drops to a dribble. Is this because of the distance, height and pipe size that I am pushing water through? eg.  head to 18m pipe 300m @ 1/14. Pump is rated to 78000 l/hour to a head of 31m. Has anyone come across a conversion chart for these factors?


I need a  :-! "



Kenso

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    * March 09, 2011, 06:21:36 PM
    #1
    There are many converters online (try googling). They take into account more factors than you have described, including the roughness of the pipe, pressure at the pump, flow rate and more.

    In my albiet limited experience, pushing a large volume of fluid through a small pipe results in a great pressure loss. This is parallel to electricity, where you must increase the wire size to reduce voltage drop over larger distances.

    By my reckonning, 100mm pipe x 300m will set you back over 3 grand. OMG.

    Best solution I can come up with is to pump the water into a holding tank up near where you want to use it, then re-pump it to get the pressure you want.

    Sorry I'm not more helpful, kenso.

    Here, have one on me... :-! "
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    Pumps in Farm Machinery March 09, 2011, 06:42:01 PM
    #2
    I will ask hubby when he gets home for you.  But I did get a lecture on electric fences once and I do remember him saying that the larger the wire the better the same as for water the larger the hose the better.
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    Pumps in Farm Machinery March 09, 2011, 06:45:48 PM
    #3

    Ta for the  :-! "  Macca, yes I concur the OMG!  :worry Yes I did google for a converter but couldnt find anything suitable. Hard to work out a search term for it... Thanks Suzie yes I think its all factors mentioned.
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    Pumps in Farm Machinery March 09, 2011, 06:54:01 PM
    #4
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    Peter
    Hobby farmer, factory worker, thrillseeker.


    Pumps in Farm Machinery March 09, 2011, 07:01:00 PM
    #5
    Thanks Sav,  :kiss:
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    Pumps in Farm Machinery March 09, 2011, 07:27:12 PM
    #6
    Yeah, like Mac said, I think pipe diameter is killing it, the difference between a 32mm pipe V's a 100mm pipe is enormous.

    This is pertinent, I have a 30,000l/h pump, owned it for 2 years and have never even started it! (Got it cheap - Gray's auctions).
    I've just recently scored some 40mm fire hose from work and picked up today some suction hose.
    I need to pump out my small dam so I can clear and clean it, plus the recent rains have totally scoured out the spillway (I managed to pick up a 400mm X 2mtr reinforced poly pipe to replace the broken concrete one).

    I've been thinking about flow rates and pressure drops etc. Later I'd like to be able to hook it up to my water tank (27k ltr) and hopefully be able to use it as a fire hose (I scored a plastic and an aluminium nozzle too).
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    Pumps in Farm Machinery March 09, 2011, 07:55:10 PM
    #7
    Haven’t had much luck with greys the only thing I buy there is vino and even that is getting ridicules! The Pump seems to be good quality just my infrastructure is letting it down! oh well thats the lesson learnt  :worry
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    Pumps in Farm Machinery March 09, 2011, 08:03:12 PM
    #8
    100mm pressure is good, 32mm pressure is woeful, 50mm pressure may be adequate.

    I checked the numbers and the 50mm pipe may work and would probably be a fair bit cheaper than 100mm. (Still bloody expensive though).

    Mac's other suggestion of an intermediate storage tank type arrangement may be the best solution.

    I've had a few successes with Gray's, had a few let downs too, I got into them ages ago, noticed the bargains are harder to find nowadays.
    Plus, it always sheets me that it's hammer fall price (and the auction extends until 10 mins after no bids) + GST + freight.
    You have to factor that into your highest bid.

    (I don't think there 's a 0pt size, try a whole number)
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    Pumps in Farm Machinery March 09, 2011, 09:19:26 PM
    #9
    My thoughts are similar to the others here.  I'm pretty sure that the friction in the small pipe is killing your pressure. 
     
    If the pump is new or at least in good condition it should have no trouble with that distance.  If the pump has been damaged by running dry or similar, it might be causing the problem. At 78,000l/hr, the pump should be filling a 20 litre bucket in under 1 second.  It's a bit hard to test accurately but at that rate even a very rough estimate should be sufficient.  If you don't have oceans of water at your 4" delivery then the pump may be the problem. 
     
    50ml pipe should be heaps if the pump is good.  We have a honda firefighter moving water about 800m through 2" rural poly no trouble.  Not sure what the head is but probably 15 metres or so.
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