Dredge Nozzle Physics

[Sierra Sam]

What's wrong with this picture?



Suction is poor at best and only when pump is going almost full throttle, and then only enough to load it up enough to block it up.

Both hoses are 10 feet long; one is 1 inch, the other (log) is 2 inch.

Air leaks not the issue.

[AuTSaurus]

Difficult to tell. Not enough pictures, or, not enough information from your one picture.
It looks like a homemade jet log (venturi), that you are attempting to use as a footvalve(?), or as a suction nozzle(?).

Greg

[Sierra Sam]

Yes, jet log. The white (1 in.) hose comes from the pump ( small Honda). The green (2 in.) hose has 6 in. metal nozzle on the end. The bare end of the jet goes directly onto header box on sluice. In pipe (jet) is apprx 1 foot and main log is 2 ft. And again, hoses are both ten feet long.

I reduced the rise from suction head to output of jet to see if it was just the uphill battle that was going on, but nothing much changed.

[Gold Seeker]

Sam,

I agree with Greg, not enough info to effectively help, but I will give it a shot.

It could be you don't have the jet angle correct.

It also could be you don't have the jet reduce enough, meaning the jet has to be necked down or have a "jet" i.e. "smaller inside diameter" where it enters the log, if your jet pipe is the same size from where the hose is connected and where it enters the log you will not get the "venturi effect" to create the suction, the venturi effect create higher pressure into the log thus suction.

Or a combination of both of the above.

That being said I'm not an expert on building jet logs, Hoser John and other more knowledgeable members with enough/more info will give you the info you need to get that jet log sucking!!!


Skip

[CalGoldDredger]

I would say that the angle is too much try about a 15 degree angle on the coupling into the jet log.
If there is not enough pressure then it will not create a good vacuum, if this is the case try to neck down the coupling to make more pressure or get a stronger pump.

[stretch]

I have to agree with Gold Seeker & Cal .Ive built a couple and I think you need a 10 degrees angle and reduce your pressure

side down to 5/8 or 1/2 inch. Make sure to angle the pressure side of your small orifice and make it as smooth as possible.

I use a plug the size of the pump side and drill it out to size I like ,then braze it in place. Hope this works for you.

stretch

[russau]

you say nozzel on the heading but jet log in the post. your log needs the angel of 11 degrees (with the flow of water/material) and probly a 1/2 inch hole for the water. and they say from the point of the high pressure water enters the log you need 10 inchs of length for every inch of suction line, to where the water/material hits the flair.ive seen them shorter.plus you didnt say what size/pressure of pump your using. for a 2 inch dredge youll need a 100 PSI pump and for a 4 inch suction line youll need a 300 PSI pump (minimum sizes) logs are built/tuned for the size pump your using.

[Hoser John]

11-13 degree has been the industry standard(95+%) for many years. The Bureau of Reclaimation conducted an amazing amount of tests on the HUGE rivers back east as they keep them open from siltation. Hence the info has made a HUGE impact on the quality of suction. The old OLD Treasure Emporium engineer lives in Auburn and he's spent over 40 YEARS trying to engineer the 100% perfect jet system. ON HIS OWN DIME TOO. The proportional ratio from induction to jet id is also yet another area of improvement(more ain't better) in preventing just drilling a hole through the side of the jet with tooooooooooooo much psi and gpm. Pump construction and on and on and on--I love it when noobs just announce to the world that a dredge is ez to engineer and they are just making their own. I've spent many $100,000's and many MANY years just tring to improve for the common good. Never restricted the free flow thought process of many minds and to LL with the patent bs--a couple a bucks in your pocket DOES NOT make you safe from china ripoffs in a few months, and benefiting the common good is a RIGHTEOUSLY EXHILERATING feeling--tons a au 2 u 2 -John

[foxherb53]

OK I read your second post I misunderstood . I thought we were looking at a suction nozzle.

After further review I would say you may need to reduce the pressure hose to 3/4.

[dredgeguy]

Hello Sam

The jet is the wrong angle to work. Weld the jet so you are aiming out the center of the big tube, it will work a lot better.