Reducing suction hose from 4" to 2" for crevices

ncclaymaker

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Aug 26, 2011
349
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NY, AZ & NV. Becoming "houseless"
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Minelab 1000, A Motorized Power Glider Trike, 17 foot travel trailer behind my Jeep. 4" suction dredge/high banker.
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I'll be going out to AZ and NV this year with a 17 foot camper trailer, hauled by my Jeep. With the water issues, not all of the stream depths will easily permit the use of 4" dredge/high banker. So a 2" might just do the trick to pick stuff out of crevices, not dredge the bottom to the bedrock. I was thinking of using my 4" power jet with the std. 2" water hookup, but reduce the intake of the power jet to 2" with a hose adapter and use 2" suction hose, instead of my 4". I don't think that it should cause anything other than reduced material flow, but a lot of suction/vacuum to extract stuff out of the cracks and crevices. Or should I just shell out the cash for a 2" power jet?

One other small item... my parts are starting to wear out and degrade, not the equipment. Getting older, but yet haven't reached the expiration date.

Yours thoughts... please.

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1637

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May 26, 2011
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tujunga ca
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xlt mxt gmz and now a gmt whites
not sure if this works the same ,but i was asking the same questions about my gas powered vacuum.and found out that anything that sucks hates to be necked down,but anything under pressure loves it .my turned out to be my end was necked down,got a new end now its works good. but like allot of stuff just try it and you will know.
the way things are going a drywasher mite be next,
good luck show us your finds.
brad
 
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Georgetown Texas T

Tenderfoot
Jun 22, 2021
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It should work fine to reduce down. You can get a 2x4" PVC to neck it down. About the only thing is you may not be getting enough water to run a 4" sluice properly.
 

Phil

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Dec 4, 2012
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It will work, but like Georgetown said, you will need to adjust the angle on the box to compensate for the lower water volume. The steeper angle means you will lose fine gold out the back (300 mesh and smaller), but it catches the bigger gold.
 
OP
ncclaymaker

ncclaymaker

Sr. Member
Aug 26, 2011
349
291
NY, AZ & NV. Becoming "houseless"
Detector(s) used
Minelab 1000, A Motorized Power Glider Trike, 17 foot travel trailer behind my Jeep. 4" suction dredge/high banker.
Primary Interest:
Prospecting
  • Thread Starter
  • Thread starter
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It should work fine to reduce down. You can get a 2x4" PVC to neck it down. About the only thing is you may not be getting enough water to run a 4" sluice properly.

Can divert water from the pump to augment water flow to the sluice.
 

Jason in Enid

Gold Member
Oct 10, 2009
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Dont reduce your suction hose. A lot of its "power" comes from the force of the moving water inside the hose. When you cut that water movement, you cut the suction. If you are wanting to work in smaller crevices, then take a 4" nozzle a flatten it some. As long as you arent pinching it, you will keep the same total volume size.
 

N-Lionberger

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Dec 1, 2013
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Arcata, California
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You can run a 2" hose into the 4" a couple feet and tie it off with some wire, it will get good suction and your sluice won't be robbed of water. If you neck it down to 2" you will have all kinds of problems with your sluice.
 

Bonaro

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Aug 9, 2004
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Olympia WA
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Minelab Xterra 70, Minelab SD 2200d, 2.5", 3", 4"and several Keene 5" production dredges, Knelson Centrifuge, Gold screw automatic panner
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Most answers above are correct.
You can usually neck down 1" but any farther and it causes problems with water volume in the sluice.
You also rely on the velocity of the water in the suction hose to prevent rock jams. Necking down to 2" will cause plug ups and clogged riffles.

What about just making a rock dam down stream of the dredge so your tailings water stays in your pool? I do this on my big dredge to raise the water level when dredging small streams
 

xracer550

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Oct 31, 2012
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Palmdale , CA
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Goldbug 2
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Try a hose splitter you will still have the water volume to run the sluice & it will suck up dry dirt as long as the splitter is underwater.
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xaos

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Jul 3, 2018
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Keene used to make a 2 inch powerjet that fit into the 4 inch jet flare assembly...All hose is 2 inch...(thus alleviating any cavitation issues... )

Now I think they want you to buy a 2 inch jet flare instead of the adapter...(there is a adapter to add a 2 inch flare to a 4 inch sluice box!)
That is a lot more expensive that the 2 inch to 4 inch taper!
Who may be able to help is your local muffler shop...get them to flare a piece of tubing for you...(4 inch to 2' is a popular size for header reduction to exhaust piping...)

something similar to this
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the sluice box is adjustable, and I always adjust it anyways depending on conditions.
 
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