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  • #31
    Re: Jetter question

    Originally posted by All Clear Sewer View Post
    if you throttle with the ball valve its not good on the pump as well, but what do I know.

    just to clear the air and set you all straight.

    a ball valve is not the best to use on an over sized jetter. it's best to size the jetter for the work at hand.

    but a ball valve will work as long as it's rated for 1.5 times the working pressure. in fact ridgid has a foot operated valve for controlling their jetters. not a ball valve, but the same as a hand wand. quick acting spring loaded valve. i only have 5 of those and 2 high pressure ball valves i use between lengths of hose for ease of adding or removing hoses.

    the purpose of the unloader valve built into every jetter/ pressure washer is to control the discharge pressure and to allow for bypass back to the tank or into the cold inlet low pressure side of the pump to re-circulate. on real cheap pressure washers there are no shut offs as the gun is a dump gun and the pressure is either high or it's being dumped

    a tank is better as the water can bypass and not get hot. a garden hose feed will start to overheat in a matter of minutes.

    but what do i know about jetters and plumbing anyways

    rick.

    ben call me for more info as all it's doing now is he said she said.

    thread done
    phoebe it is

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    • #32
      Re: Jetter question

      Hey! you can't close a thread!!
      sigpic

      Robert

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      • #33
        Re: Jetter question

        Originally posted by westcoastplumber View Post
        Hey! you can't close a thread!!
        I'm still wondering when you're going to come pick up the brand new KJ-3000 I have sitting here. As a matter of fact I will even throw in a older electric jetter which needs a little work.

        Mark
        "Somewhere a Village is Missing Twelve Idiots!" - Casey Anthony

        I never lost a cent on the jobs I didn't get!

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        • #34
          Re: Jetter question

          Originally posted by ToUtahNow View Post
          I'm still wondering when you're going to come pick up the brand new KJ-3000 I have sitting here. As a matter of fact I will even throw in a older electric jetter which needs a little work.

          Mark

          I actually do need a jetter, could have made some money with it already, but not enought to warrent the purchase of one yet. Tax time mark, I have it on my list of things to purchase

          thank you mark, zeljka say's hello to you and brenda
          sigpic

          Robert

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          • #35
            Re: Jetter question

            Originally posted by westcoastplumber View Post
            I actually do need a jetter, could have made some money with it already, but not enought to warrent the purchase of one yet. Tax time mark, I have it on my list of things to purchase

            thank you mark, zeljka say's hello to you and brenda
            Since Brenda and I have decided to adopt Zeljka you are now like a son-in-law. I can offer you a really good price and easy payment schedule over the next 10-years if needed.

            Mark
            "Somewhere a Village is Missing Twelve Idiots!" - Casey Anthony

            I never lost a cent on the jobs I didn't get!

            Comment


            • #36
              Re: Jetter question

              LOL, you have a deal, you can have zeljka Kidding, we can share her, there is enough sweetness to go around.

              She feels the same about you guy's.
              sigpic

              Robert

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              • #37
                Re: Jetter question

                Well Rick
                thank you on setting us ALL straight, On what???
                Originally posted by PLUMBER RICK View Post
                or you can use a high pressure ball valve on the discharge jetter hose and throttle it down.
                rick.
                I dont really know, but Thanks just the same

                BTW.... the "What Do I know" is my line, Get your own.....rotflmao
                Last edited by All Clear Sewer; 01-06-2008, 06:20 PM. Reason: Just to get under Ricks skin :)
                http://www.all-clear-sewer.com/

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                • #38
                  Re: Jetter question

                  power (in hp) = flow (in GPM) x pressure (in psi) x .0005833

                  7.5 gpm x 3000 psi x .0005833 = 13.1 hp

                  for 100% efficient pump

                  and a 100% efficient gearbox

                  a gas engine's max power output comes at a specific rpm, but I would expect a small 4 stroke to have a pretty flat curve, and a smart manufaturer will have done their homework regarding power curve of the engine and the gearbox they choose, so I would say (at sea level, power starts dropping off dramatically above 5000' elevation for anything without forced induction of some sort; a turbo or a blower) your results are believable (especially if, as I infer, you've tweaked the governer a little) if on the ragged edge.

                  Math is a tool for prediction; you've got the actual animal and if it's doing it, it's doing it.

                  -Alex
                  This is my reminder to myself that no good will ever come from discussing politics or religion with anyone, ever.

                  Comment


                  • #39
                    Re: Jetter question

                    Thanks, I'll have to remember that formula. I like the saying about the math.
                    Buy cheap, buy twice.

                    Comment


                    • #40
                      Re: Jetter question

                      Originally posted by gear junkie View Post
                      Been looking at one, not because of Rick, Joey. I saw a jetter that has 7 gpm at 2700 psi. Saw another one at 3500 psi with 8 GPM but this one is a pressure washer. Both are carts. Is there any reason not to use the latter? A jetter is just a pressure washer so the conversion shouldn't be that wrong? Add a reel with hose and that should be it, right? The latter PW's company said that rating was sustained and not spike pressure. How do you know which pressure the companies are advertising? Is there any disadvantage to having this much gpm from a cart jetter? Is there any reason not to use a warthog jetterhead for everything? If it does roots, grease should be no problem? Last question; how do you figure out pressure loss for jetter lines?
                      Only disadvantage I can see to higher flow is that, in my experience, I start starving my pump at about 6gpm when fed from a garden hose. This kills pumps quick. You will have to take care to drop your rpm when you have less than stellar supply to avoid starving the pump. Run off a tank and the problem goes away, but you have to lug a tank around.

                      Higher pressure rating hurts nothing, just adds some expense and weight.

                      For jetting, I think, and please correct me if others have had other experiences, going from 3000 to 4000 psi at the same gpm does little to change results. Going from 2 or 3 gpm to 5 or 6 at the same 2500 to 3500 psi gives dramitically better results. I will be buying some nozzles soon, and will be experimenting with drillings and will post results. This will all be on 5.5 gpm machines as that is what I have. Any thoughts on sizing nozzles to cut roots at this gpm greatly appreciated. I lose about 1000 psi through 300' of 1/4" hose.

                      I have fallen into a habit of just leaving my unloader cranked in and controlling pressure with rpm. This started by accident, because I stripped out the threads on the handle of an unloader, then continued as I was too busy/lazy to replace it. I've had no ill effects from this yet. Any thoughts on how I will pay for this later?
                      This is my reminder to myself that no good will ever come from discussing politics or religion with anyone, ever.

                      Comment


                      • #41
                        Re: Jetter question

                        Originally posted by Ace Sewer View Post
                        power (in hp) = flow (in GPM) x pressure (in psi) x .0005833

                        7.5 gpm x 3000 psi x .0005833 = 13.1 hp

                        for 100% efficient pump

                        and a 100% efficient gearbox

                        a gas engine's max power output comes at a specific rpm, but I would expect a small 4 stroke to have a pretty flat curve, and a smart manufaturer will have done their homework regarding power curve of the engine and the gearbox they choose, so I would say (at sea level, power starts dropping off dramatically above 5000' elevation for anything without forced induction of some sort; a turbo or a blower) your results are believable (especially if, as I infer, you've tweaked the governer a little) if on the ragged edge.

                        Math is a tool for prediction; you've got the actual animal and if it's doing it, it's doing it.

                        -Alex
                        alex thanks for the formula you posted as i have it saved from old work.

                        keep in mind that a gas engine is only approx. 67% as efficient as an electric motor.

                        let me show you an example of this.

                        the same company has a 3gpm @3500# electric jetter that has a 6hp. electric motor on it.
                        in a gas model it has a 9 h.p gas engine for the same results.

                        another example is the 3.5gpm @4000# with a 7.5 h.p electric.
                        in gas this is a 3.5 gpm @4000# with 13 h.p gas engine.

                        4gpm @4500# 10 h.p electric or 4.3gpm @4500# 16h.p gas engine.

                        here are some other specs. on other high volume machines.

                        these are with high quality honda or kohler engines.

                        18 h.p 5 gpm. 4000# 18 h.p.

                        20 hp. 8gpm 3200#- 20hp. 6gpm 4000# -20 hp. 7.5 gpm 3500#
                        20 hp. 4.5 gpm 5000#

                        24hp. 8gpm 4000#

                        24 h.p 9 gpm 3000#

                        24hp. 10gpm 3200#

                        27hp. 9gpm 4000#

                        27hp. 12 gpm 3000#

                        27hp. 15 gpm 2200#

                        so in a gas model your 13.1h.p formula would require approx a 20 h.p engine.

                        these are real published established numbers from companies that make pressure washers and jetters.

                        in reality the largest portable electric jetter that we can use in the field is a 2 h.p 1500 at 2.1 gpm and this is drawing 17 plus amps under load. that's with a good efficent motor.


                        there are plenty more examples but you get the point.

                        if i am able to scan my catalog's i can show pages of pump and ratings.

                        my portable gas jetter is a 5.6 3000# at 18h.p at 20.2 hp i can hit 3500# with an electric motor this requires 13.5 ebhp. (electric braking horsepower)

                        rick.
                        phoebe it is

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                        • #42
                          Re: Jetter question

                          another quote right from the manufactures book

                          gear reduced pumps have a 2.2 to 1 ratio. pumps require a 1450 rpm ideal. so the desired engine rpm is 3190 to equal 1450 on the pump.

                          "note: you will always have to overpower your engine when using a gear box. why? if your desired performance specifications call for a 16hp. engine remember that h.p. is rated at full engine rpm (3600). with a gear box you can't run that high. under load using a gear box your engine should be running between 3180 and 3250 rpm and that will not produce 16h.p."

                          these are published facts, i'm not winging it or making it up.

                          then you have nozzle concerns too. at 3000 psi and 5.6 gpm you would need nozzle that has an equivalent drill size of just under 6.5 but at 3500 psi you would need a nozzle size of just under 6.0

                          the reason is the volume stays the same and to increase the pressure you need to restrict the opening.

                          any company that sells pressure washers or jetters will ask for your machine specs to properly size the nozzles or jets. there is no universal nozzle. plenty are interchangeable. the nozzle size is equal to a 4000psi output. so a number 2 nozzle will put out 2gpm and a #10 will do 10 gpm. everything in between is a 1 to 1 ratio at 4000 psi.

                          so on a jetter nozzle the number of openings would have to add up to the actual nozzle number. so a typical 4 hole jetter nozzle a machine putting out 5 gpm @4000 would require a #5 nozzle hole divided by 4 openings would work out to a a 1.25 opening per jet orifice. then you have wear on the nozzles that will enlarge over time. along with pressure drop on the total i.d. size of hose and length.

                          if you have a test gauge attached to the end of a jetter hose and a jet nozzle on the hose. you can run it into a capped 2'' gal line and let it wash back into a bucket. watch the gauge for the pressure and measure the trapped water for the volume.

                          you can't accurately measure pressure from the machine manifold. the pressure needs to be measured from the outlet next to the jet.

                          or you could buy a $300. plus high pressure water flow meter to measure both pressure and flow. but even this is useless unless it's near the outlet of the jetter nozzle.

                          food for thought when sizing a pressure washer or jetter.

                          remember gpm is more critical than psi. getting the psi up is cheap
                          getting the gpm up is spendy.

                          2500# at 10 gpm. is better than 3500# at 5gpm. and much more money and horsepower too. too much gpm is an overkill and messy on smaller lines.
                          size the jetter as you would size you cable machine. there is no 1 size fits all.

                          but a 11h.p-13 h.p 3000#-3500# 4gpm is a good start for 2-4'' pipe. most common size out there

                          good luck with all this info.

                          rick.
                          phoebe it is

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                          • #43
                            Re: Jetter question

                            http://www.all-clear-sewer.com/

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