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  • #16
    Re: Making an Old Trailer Jetter New

    Originally posted by SuperPro View Post
    These are just engine/motor horsepower capacity formulas. Torque is also the factor to consider. A gas engine produces peak hp & torque at certain & different rpm's. An electric motor produces peak hp & torque instantly upon start-up. This is why an electric motor will be less hp than a gas engine for the same application. The formula gpm x psi / 1100 is the minimum hp requirement, an may require bumping up a couple of hp. Let's say peak hp of a 20hp engine may be 3000 rpm, so running it at 1000 rpm just won't do the job, it may only be producing 15 hp or less.
    point taken, but look at the application; we run constant displacement pumps off small engines. you gear or belt drive or whatever to match the rpm of the engine to the rpm of the pump. small engines are usually set up to govern out at 3600 rpm, so youd gear it to hit 3600 rpm at the max rpm of the pump (or, if you are me, 3400 rpm so you can push your pump just a little when you want to).

    small engine tourque curves are real flat, so, yeah, at 1000 rpm the engine is not making near rated hp, but it doesn't have to, because it is only turning the pump at part speed, so the flow is lower, and the hp requirement is less.
    This is my reminder to myself that no good will ever come from discussing politics or religion with anyone, ever.

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    • #17
      Re: Making an Old Trailer Jetter New

      my jetter has a 4130 pump and 25h kohler the manufacturer specks say 2k psi and 15 gpm .a higher psi would be great if the conversion would work w/my present motor. i do almost all 4" so lower gpm wont hurt . i am still figuring out this jetter game.

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      • #18
        Re: Making an Old Trailer Jetter New

        Originally posted by pipe doc View Post
        my jetter has a 4130 pump and 25h kohler the manufacturer specks say 2k psi and 15 gpm .a higher psi would be great if the conversion would work w/my present motor. i do almost all 4" so lower gpm wont hurt . i am still figuring out this jetter game.
        Probably need to swap to a different pump. Might also need to change pulleys to get correct rpm to new pump. I'd think yr 25hp kohler would do 7.5 gpm @ 4kpsi.
        This is my reminder to myself that no good will ever come from discussing politics or religion with anyone, ever.

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        • #19
          Re: Making an Old Trailer Jetter New

          Originally posted by Ace Sewer View Post
          Probably need to swap to a different pump. Might also need to change pulleys to get correct rpm to new pump. I'd think yr 25hp kohler would do 7.5 gpm @ 4kpsi.
          what would be the biggest gains lowering gpm and ^ pressure . we do mostly P M on hotels strip malls and grocery stores ,with this jetter 4"-6"? 400' of 1/2"

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          • #20
            Re: Making an Old Trailer Jetter New

            yr out of my experience there... i can help on theory and design, but I rarely see over 4", and almost never bigger than 6". I do fine on that with 5.5 gpm. 'course, I'm not doing 400' runs. 160' about the longest I see. Think you'd do better asking around with guys who run bigger stuff regularly on best pressure and flow. Nothing beats experience. I can help you pick a pump and set it up, but I don't know what'll pull 400' best.

            If I was you, I'd think about what my complaints were with my current setup. You've said youd like to get some more p, and are willing to sacrifice some Q to get it, but I'd go back up a step from that and ask myself what do I think I'll accomplish with that p that I can't do now, and start thinking about if that is the best way to do it.

            with 1/2" at 10gpm, you lose maybe 500psi in 400' of hose . Most of the charts I'm seeing don't even list a rating for 15 gpm in 1/2", the one that does suggests you'd lose ~1kpsi in 400'. The p loss in hose is minimal at low flows, pretty linear for a while, then goes off the chart when you try to push too much through it. From what I'm seeing, 15 gpm through 1/2" is getting into that off the chart area. So I'm guessing youd do better with larger hose (if it will not be too stiff to make the turns; if it's all straight runs then I'd think just get bigger hose and appropriate nozzles and 2kpsi would work) or more p and less flow. But I'm guessing. Talk with someone who does it.

            for the record, if I was setting one up with my limited experience, and it was a trailer with a tank, and was planning on 6" lines and 400' runs, and some 4" lines with some 4" bends, i'd steer towards 7 at 5kpsi at first, but I'd have to go looking at bend radii in 3/8" hose rated at 3,4, and 5kpsi, see how stiff the hose gets when you uprate p, and maybe end up with two hose reels or something
            Last edited by Ace Sewer; 08-19-2011, 03:59 AM.
            This is my reminder to myself that no good will ever come from discussing politics or religion with anyone, ever.

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            • #21
              Re: Making an Old Trailer Jetter New

              be careful with 1/2'' hose on 4''. 45's are no issue, but hitting a 90 or short sweep san tee, can get tricky. plus 7.5gpm is still possible with 3/8'' and some pressure drop.

              i have multiple reels on my jetter. 1/2'' x 500', 3/8'' x 400', 1/4'' x 150' and 1/8'' x 100'. plus lots of loose jumpers in both 1/2''. 3/8'' and 1/4''.

              at 7.5 gpm, i would still stick to 3/8''. 1/2'' is a little overkill.

              also with inside jetting, i would be very concerned with too much flow as you're jetting with the flow, creating a potential backup/ backwash. now going upstream, higher flow is not much of a concern. but seldom can we go upstream in interior plumbing.

              7.5 at 4000 is a good number for inside work. outside c/o i will go a full 12-18 gpm,, depending on nozzles and hoses.

              also inside work a shut off/ foot valve is very important, especially with those flow numbers.

              i use a hand held wireless remote flow control. not as instant as a foot valve. but it allows me to have full flow without the pressure and volume loss through a foot valve. also my machine didn't have an unloader valve so shutting off water has to be done at the machine via a bypass valve.

              i added an unloader for 3/8'' flow and added my own remote actuator. saving a cool $4500 from a factory setup. plus i have more control over the remote with variable flow via my remote and actuator controller.

              lots of learning when you get into high flow and pressure.

              rick.
              phoebe it is

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              • #22
                Re: Making an Old Trailer Jetter New

                Rick, what did you use for a wireless control valve?

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                • #23
                  Re: Making an Old Trailer Jetter New

                  Originally posted by SuperPro View Post
                  Rick, what did you use for a wireless control valve?
                  do tell with pics.

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                  • #24
                    Re: Making an Old Trailer Jetter New

                    i've posted them before, but will have to dig them up.

                    the 3 way ball valve is connected to a linear actuator and the actuator is controlled by an electronic actuator controller with the ability to have it stop at my preset positions. the controller is activated by a wireless remote and or a truck mounted push button or remote wired foot pedal.

                    i can do 100% open or closed and 50%-50% open close.

                    the entire system i pieced together from off the shelf parts and electronics. probably under $400.00 invested including 100' of 14-4 electric cord for my wired foot pedal i've never used. the 3 wireless transmiters are good from 200' -1000' with the antenna extended.

                    pictures are buried and i'm late to dinner

                    rick.
                    phoebe it is

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