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Nozzle or Jet


Steel Pan

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It's been a long time since I saw this topic come up.

And, as I remember,.... :89:

A nozzle works better in shallow water as it is a little bit more forgiving

should you raise it out of the water during operation.

BUT, the Jet makes use of only one hose to the dredger, has better

suction, and works best in deeper water due to the lesser possibility of

the user causing cavitation.

Now, what's this about using a caution cone at the Jet? :idunno:

Increased efficiency? Does it suck better?

(Hmmmm, isn't "suck better" an oxymoron? :brows: )

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I don't think it's cavitation proper, it's just that when you pull the nozzle outta the water when using a jet then you are going to lose the prime on the jet. Since the pressure line goes directly into the jet and into your flare you are going to rooster tail out high pressure water straight outta your box.

With a suction nozzle, it's the nozzle itself being primed by the pressure line, and the pressure flow is directed right down the center of the suction line where it connects to the nozzle. So you won't rooster tail your sluice if you pull it out of the water.

Also, there is some debate as to which nozzle has "better" suction. There has been some studies done that show that using a suction nozzle in place of a jet connected directly to your flare actually has greater suction than a jet. If you look at the pressure line inlets in both a jet and suction nozzle I think you can see why. One goes straight down the nozzle with no resitrictions, the other (in a jet) usually hits the side of the jet tube at some angle, dispersing energy.

I wouldn't use a suction nozzle on anything bigger than a 3" personally. Way too unwieldly (2 hoses versus 1, plus the nozzle is just lots bigger and no swivel). Unless you really got some shallow pay that needs dredging. Suction nozzles also clog up way way more than jets, especially if you are using a jet with one of the newer style quick connectors that have no internal upsets between the hose and the jet.

Edit: caution cone? never heard of anything like that. :idunno:

Edit 2: Also there is some debate that suction nozzles actually get better recovery rates because the slurry can settle by weight in the hose before it hits the sluice. In a jet setup it does too, but then it's reagitated when it passes the pressure inlet in the jet right before it hits the box. But with a suction nozzle it's usually going into a crash box or something similar that agitates the slurry too. So I think its a tossup.

Edited by JasonG
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Hmm first I heard of the caution cone so I'll let someone else take that part. You can make a much beefier and longer flare by cutting a piece of plastic pipe in half, splitting it into a "Y" and plastic welding plates onto it though I think. Or really flares are pretty cheap to just buy.

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Jet vs Suction nozzle was answered many times at demos with our company at the Annual Jamboree at Follows camp in Azuza that we worked every year. Same pump/engine combo,picking up a small bowling ball. Both nozzles were de-ringed as you can't get good suction with the relief ring offset as disallows a complete vacuum. With a tape measure simply got closer and closer till picked up-done 5 times with each for averaging purposes and each time powerjet (both keene) was the winner.For extreme fines areas the suction nozzle allows better recovery by less turbidity at the point of introduction to the box and hose length allows gold to settle to the bottom of the flow WITHOUT the pj remix prior to introduction into your drdge box. Just like the blast off tests as Precision pumps(much closer tolerances)always won for both suction and blow by the farthest distance. That was fun testing for visitors as when 100+ in the canyon a good drednching was greatly appreciated. We made flares to help compensate for the huge suction increase of the pressure chambered fed tri jet to deaireate,slow down,spread out the flow and increase gold recovery as ifn' it don't drop ASAP then inertia builds as speed of motion in the box increases ,along with the box angle , and adios your oro puro. So much fun and tax deduction to boot-John

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Edited by Hoser John
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John, I know you've played around with dredges quite a bit, so can you explain, or anyone else for that matter,

what's up with a "flare" added to a Jet? :89:

Does it increase suction like using increasingly larger dia. pipe when running water downhill? :idunno:

( I already got me a new "plan of operations" for next year. :brows: )

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On the 10" 2 vw run precision were utilized but over 30++' deep a extra 50 hp and a second/3rd pj was needed for that gravel sucking monster. Also on a 8" at Drivers Flats we used a sn and a pj to increase suction. Did many MANY tests trying to work with air assist rings on the nozzles but foaming frothing mess once expelled caused too many problems. Even a boilerbox style header,fed into the box was just too hard to break up them bubbles that float away small gold and fines..Flared was strictly a deaireation,spread out a even flow and get that gold to drop asap measure. We dropped all production of dryland blasters nozzles as too many folks refused to wear eye protection and always used extreme caution ,and lawyer, to eliminate injury to anyone as sales miniscule in proportion to dangers to customers.John

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