Octa-Jet

yes , I saw the video on other forum, really interesting. it got me thinking on how to make it bigger and with no plastic. and if it would work. still be fun to try and build if you have time. 50 ton press, milling machine and lathe would be nice also. I would like to try a 9 jet in 10 inch.

bill/cr
 

infinity jet is better one that is built right that is !!! but hard to build. this jet looks pretty easy.

bill/cr
 

I love the idea of increasing suction while using a little less throttle. It seems that with my current jet/pump, I need to run the rpms at around 2340 and not around 2280 that I was running. I had much less plug up in the hose and jet and a ton more suction. What bothers me at that rpm is my water speed through my box but it seemed to work great my last outing. See my other thread :) My jet is on it's last leg imo and don't want to buy/build one when I'm going to build a 5 or 6" dredge for next year. I plan on using the pump/motor I have and just buying another and also using the pontoons I have, just adding more flotation. She'll be a ugly beast but as long as it works, that's what matters lol.

Back to the OT, I do like the simplicity of the octa-jet, looks easy to build, I agree with you on that Bill. I just want to know real word on how it works.
 

Wrong induction angle,plastic and I for 1 will take my ol'trijets design fed with a pressure chamber anyday in every way. Good ol'GoldDivers jet rocked like crazy too. Wish ol'Tom Ashworths Prospectors casche was still around as a HUGE thread with MANY of the innovators/inventors of the goodies posting pics/diagrams and such. Go to search here as a huge amount of info on this subject late 2011 if memory(hahaha) serves me right. The thread utilized a metal fitting and MUCH better couplejet design for 360 degree induction.When running just a small 4" it's just not that big a deal as not moving that much water but 6-12" and then it really matters much more as 100s the times water and materials moved. John
 

yahoo :hello2: found some info for ya-John
 

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The octa-jet/multijet design works great. I am the Goldsnare guy who came up with this design to overcome the problem with infinity/couple jets as we like to call them. These ring jets have been around for over a hundred years but are prone to plugging and require cleaning or extensive filtering at the footvalve when uses for dredging. The multijet delivers the suction power like a ring jet, but does not clog from small debris and is self centering. I am currently testing a 4" jet running off a honda2.5/p90 combo and have 16inchesH20 of suction. Pvc is not an issue with the smaller jets and is very durable, but I will be looking to make the larger ones out of metal because the weight can be reduced.
 

Thanks Omnimicron!

The design came out of necessity as most things do. I had been using infinity jets for over two years and they work great for energy transfer to the water column creating terrific suction, but as I decided that I should sell my product to the public I was looking at every potential problem that could affect it's performance and ease of use. The infinity jet was a problem waiting to happen and required to much user interface to keep clean.

The multijet design was a fairly simple extension built on my experience with the infinity jets. It took several attempts to get it right, but it is a fairly easy build. The key to it's operation is the aperture angle/flare which can be built to provide the best angle of jet stream so that they meet in the middle with the right degree downstream angle(like putting a finger on a hose and adjusting the stream angle). Since the rear of the pressure housing is part of the inlet tube flare, there is no losses incurred by feeding the high velocity water through angled tubes into the jet like a trijet. The main thing in building a jet I have found is to not restrict the waterflow until the point of the jet, so the housing must be large enough between the two pipe areas to handle the volume supplied. As far as induction angle goes I find that a straight side inlet provides good pressure and flow equalization to the jets. Not sure if angled inlet will improve operation worthy enough to have to use longer hose or other adapters from the pump supply, but worth checking on.

I have made some minor changes to my 1" jet since I made the video and have increased it's performance also. I have found that increasing the size of the outlet tube to accommodate approximately half of the water supplied to the jet by the pump helps provide more suction and reduces jet turbulence significantly which creates a nice flow out of the jet unlike the flailing turbulent water discharge from a standard log jet.

Jet testing- I have found that a jet should be tested with a manometer two ways.
1. Closed end testing - manometer tube fed into jet with capped off end. This provides a level of "clamping power" (what you feel when putting hand over jet)
2. Open testing - manometer fed through side port with full flow through jet. This test provides level of actual suction volume through the jet.

Log jet's have good clamping power but they fall significantly lower in scale when measuring volume through open testing.

I think a well designed jet should achieve fairly similar readings of both tests with the closed test being slightly higher. Of course it must be stated that this design is for a dredge which requires little in the way of lift after the jet. A smaller outlet tube will achieve higher lift after the jet, but reduced suction volume must also be taken into account.

Omnimicron- what size jet are you running now? It may be difficult to swap out a jet that uses a smaller diameter outlet if this goes into a flare etc.. without having to cut back the flare.
 

I'm using a 4" jet, It's not oversized or anything. My flare is slotted on the log side 4 times to allow clamping. I have about 3" of total lift to the back of my sluice empty of cons, running just water and about 2 3/4" after running for a hour. I'm running a Subaru EX17 6HP engine with a Proline HP350 pump.

This whole year of running I was having issues of jet plug ups, matter fact one after another none stop. While looking at my log, I noticed the side opposite the jet was really beat up from rocks being blasted into the side when hitting the stream of water. I even made my nozzle restrictor smaller, 3.5" vrs 3.75 but that really is not the problem. It's the rocks that are longer on one side then the other. I'm assuming when hit by the blast of water then were being jammed sideways. Any way, on my end the temp solution was to increase my rpms to 3340 to 3400 from 2280. I despise Band-Aid fixes.

With that all being said, I really see the potential in your jet design. The most obvious being the force of water being directed to the middle, thus eliminating rocks being blasted sideways. Increased suction while using less throttle being another.

One question does come to mind though. If the output tube is smaller and the suction is increased, is this not caused by the venturi effect? I'm trying to remember my Fluid Dynamics class from years ago, so please forgive me if I get this wrong. With this increase in suction, (pressure differential) your having a increase in velocity but a decrease in volume. Once again, please forgive me if I get this wrong as I'm trying to remember a crash course I had years ago in fluid dynamics.
 

I probably mis-represented the question. In the multijet design I like to increase the diameter of the outlet of the jet to accommodate some increase in water from the pump. This results in a greater diameter needed for connection to the flare which could be an issue with direct replacement of a jet that has a smaller diameter. The larger diameter exit combined with the force of water being centered reduces plugging dramatically inside the jet which is a nice feature.

Currently I am testing the 4" with the same diameter PVC since there are not many options to go 4.25-4.5 in PVC. I will be building some out of stainless or anodized steel in the future, but for now I simply need the jet to test a 4" dredge design.
 

Have a look at this link. This guy has obviously done a lot of research.
 

Same basic principles applied for this one. More jets influence greater area of the water column, provide great suction, little to no clogging. I am not clear on why he is testing the jet out of the water instead of attaching a hose to the jet outlet and raising the hose only to provide lift/suction test results. Having no load on the jet outlet does not provide any relative usable information as far as I can gather.
 

i still like this homemade jet the best, very easy to scale up. but with any circle jet you need a good foot valve and screen. the jet in the above post looks nice. well built. i was not impressed with what it did. 18hp it should suck the chrome off a trailer hitch. the pebbles and algie passing thru his hose looked to be moving about 2 foot a second . not near enough for running 3 bar of pressure. i hope his dredge was built as a test bed for his jet. doesn't look like it would work well in real world dredging.

bill/cr

http://www.treasurenet.com/forums/dredging-hi-banking/190343-infinity-jet.html
 

The numbers he referenced in the video are some very strong suction values and are closed loop test values as far as I can tell. Hopefully he will do some more relevant testing and reconfigure the dredge to at least keep the jet submerged.
 

Good tip Timber , if you have the time and resources to do it I say go for it. If there is a will there is a way.
 

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