Small engine driven water pump

Discussion in 'Machinery' started by Half Pipe, Jun 15, 2018.

  1. Half Pipe

    Half Pipe Member

  2. Looks ok to me.

    A 3” bore will have way, way less frictional loss along the pipe, than a 2” pipe.

    For that size of portable pump 3” is about the biggest you can reasonably expect to go.
    Half Pipe likes this.
  3. Speedstar

    Speedstar Member

    Scottish Borders
    We have had a few like that,cheap but they only last a year or so as they break the end off for crankshaft were the impeller drive's from
    Half Pipe likes this.
  4. Half Pipe

    Half Pipe Member

  5. Kidds

    Kidds Member

    The flow rate chart for that pump says it will work at that head, assuming minimal frictional losses through a 3" pipe it should be fine.
    (someone more educated on such matters should be consulted before using my assumptions)

    Half Pipe likes this.
  6. Half Pipe

    Half Pipe Member

    Pheasant Surprise likes this.
  7. Mursal

    Mursal Member

    Hire first, then decide ...............
    Hire as close to the spec of the above pump, as you can

    Wonder can you get replacement crankshafts for them?
    Half Pipe likes this.
  8. Total static head = 10m - (-2m) = 12m

    Approx. frictional head loss of 150m of 75mm pipe = 18m (according to frictional loss calculator for 55 cube/hr of flow)

    Total differential head needed at pump = 12m + 18m = 40m 30m

    Pump has 34m of head in total (8m suction + 26m Pressure)

    Edit - doh! can’t add up!!! 12 + 18 = 30!
    Last edited: Jun 15, 2018
    Half Pipe likes this.
  9. Half Pipe

    Half Pipe Member

    @Pheasant Surprise
    The part that puzzles me, I presume flow rate drops as head rises!?
    Does this mean the friction loss in the pipe drops or does the shear weight of 3" of water in a length of pipe stop flow.

    My 2nd thought , if pump not capable, would it manage if had a 2nd pump at 75m?
    What problems would this create?
  10. Half Pipe

    Half Pipe Member

    Like the idea of hire 1st easiest way to see if works or not.

    I would think replacement crank be available as most copies of yanmar style engines. But cost of replacement crank and work involved probably means engine be scrap
    Mursal likes this.
  11. So for a given size/smoothness of pipe the frictional loss increases as you increase the flow. Try it in the calculator for different flow rates. You must assume a flow rate that the pump can manage as per below.

    The Hyundai pump head vs flow diagram assumes just static head (as they don’t know about what length /size pipe your using) so that is the theoretical volume of water the pump will shift for a particlular static head.

    The total dynamic head @ the pump = frictional loss (of pipe at said flow) + static head.
    Half Pipe likes this.

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