2" Dredge Suction

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Millz90

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Sep 26, 2014
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Hey guys....I'm trying to figure out a way to test my 2" dredge and validate if it has the max amount of suction I should be getting.

Is there anyway to test it?

I am running a harbor freight 6.5 horsepower, 150 gph motor that when running doesn't seem very strong at all.

My hardware is one of those 'Y' that the out of the water pump runs into and then the box, and the 10' or so of the actual 2" sucking hose.

It just seems like I should be sucking/processing up WAY more dirt then I am but maybe I just have higher expectations then I should since I have never seen or used a different dredge.

Which is why I'm wondering if there is a way to test the suction to see if I am getting enough.
Is there a way to increase the amount of suction power with the equipment i currently have?

Any help would be appreciated
 

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150 GPH sounds wrong in comparison to the 6.5 HP :icon_scratch:

Understanding that the venturi effect is the squeezing of a volume of liquid under pressure through a smaller orifice which in this instance produces a jet of liquid to surge up a pipe causing a vacuum behind it and then dependent upon where it is positioned in the pipe pushes or pulls the material you are vacuuming ...


Also the discharge pipe with the sucked up material within it has back pressure in accordance with its length and gradient into the hopper/header box and so this too must be kept within the parameters of pump capacity and the flow your sluice needs or can handle , understanding that it is best to suck upstream from your hi banker ...


In other words larger delivery pipe diameter under greater pressure delivering greater GPM to the orifice the more suck you have ... PSI and GPM working together to produce the a/effect and therefore not only is the delivery pipe diameter part of the equation but also its length so keep it short and unrestricted in accordance with the pump outlet as it is ultimately the pump capacity which dictates weather you will have to much suck or to little, understanding of course one can only squeeze so much water through an orifice seeing water can be pressurized but not compressed ...
 

My hardware is a Y ???Say what d l? What type of jet are you using-suction nozzle or powerjet? 150gph won't run squat-you need that a MINUTE to run good-John
 

My HF pump is 5.5 hp 2'' it pushes almost 10,000 gals. per hr. you might want to check yours 150 doesn't seem right.
 

Sorry it is 150 gal per MIN



and it's a power jet. Looks like a Y to me lol
 

The hose going into the pump is 2" and out is 1 1/4" or 1 1/2", I can't remember right not without measuring, and the suction hose is 2" on both sides.

Does that sound right?

I mean it sucks up rocks and stuff and rocks get stuck on the end that I have to take off but.....I just fell like it should have more. Is there a way to get more out of it?
 

A jet is a Siamese not a wye. The angle is EVERYTHING. You have to match the jet to the pump, although the smaller it is the more forgiving it is. The inside of the pressure side of the jet is tapered and the final diameter is what makes the magic happen.... and this is what you need both the volume and pressure to be just right to make the vacuum happen. Truthfully, with a 2", you'll spend less if you just buy one. You'll save even more with a decent used one.

If you ABSOLUTELY have to make something there are plenty of PVC suction nozzle DIY plans/ How to's out there, try one of them rather than a jet

ratled
 

I built my jet there is some math involved and angles. Mine works good but I would buy one next time. I have the same pump as you it looks like they put a smaller pump on it. The pump on mine puts out more gpm.
 

So are you thinking mine isn't sucking enough or are you just saying if I wanted to try to get more auctions it would be better to just buy a new then reconfigure my existing?
 

nh.nugget said:
I built my jet there is some math involved and angles. Mine works good but I would buy one next time. I have the same pump as you it looks like they put a smaller pump on it. The pump on mine puts out more gpm.
Click to expand...

And are you happy with your suction from it?
 

Also is the suction nozzle better than the jet pump set up?

I'm sure there are many theory's and options on that question but....?
 

The suction nozzle will have greater suck at vacuum inlet in comparison to the power jet ... but the power jet will have more pulling power at depth because the outlet of vacuumed material is shorter and this because of how the venturi a/effect is built into the system ... understanding that in this instance material being vacuumed are solids and require an unobstructed path through the pipe and so with the nozzle being at an angle allows the jet surge from the venturi a/effect to not only be centralized having its jet surge parallel to center of vacuum pipe but closer to the material being sucked whereas the power jet being positioned in a flat section its angle of inlet is off center but because of a number of factors its pulling capacity is greater than the pushing capacity of the nozzle provided no air enters the pipe ... which matters not to the nozzle dependent to its length of prime ...

Also the pump pressure capacity you have is 42.2 PSI which is just shy of 3 bar ( I have 4 bar at my kitchen tap ) which equates to 30 meters or 98 feet head ... so you are not going to have great sucking capacity unless you upgrade the pump on your moto ... understanding that centrifugal pumps have restrictions and also tolerances in design in reference to particle size they allow through the pump which a/effects the pressure capacity ...


And therefor this is why nozzle's are for shallow dredging and power jets are for deep dredging :icon_study:
 

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Millz90 said:
Hey guys....I'm trying to figure out a way to test my 2" dredge and validate if it has the max amount of suction I should be getting.

Is there anyway to test it?

I am running a harbor freight 6.5 horsepower, 150 gph motor that when running doesn't seem very strong at all.

My hardware is one of those 'Y' that the out of the water pump runs into and then the box, and the 10' or so of the actual 2" sucking hose.

It just seems like I should be sucking/processing up WAY more dirt then I am but maybe I just have higher expectations then I should since I have never seen or used a different dredge.

Which is why I'm wondering if there is a way to test the suction to see if I am getting enough.
Is there a way to increase the amount of suction power with the equipment i currently have?

Any help would be appreciated
Click to expand...

Can you provide a picture of the "Y" jet? A "Y" off the shelf adapter will not work well. Do you mean a powerjet?
The pump is certainly capable of running a 2" with great suction with the right setup. How high above the waterline is the "box" inlet? I would suggest lifting no more than 1ft above the waterline with the limited PSI available of that pump.
If your working shallows a lot then a suction nozzle is best so your not losing prime on the jet when sucking up air.
 

Like has been said, the venture of the jet needs to be matched to the pump. what diameter hole did you drill into the high pressure port of the venture to make it work so far? this will make or break your suction! can anyone give the formula to achieve the proper balance for a pump to a venture ?
 

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"what diameter hole did you drill into the high pressure port of the venture to make it work so far? this will make or break your suction!"


Too right ... and I was a bit disappointed when looking into the back of my 2" Jobe nozzle to see the venturi orifice within the 1" pipe was not tapered to suit but appears as a flat washer welded in situ >:( .... but not knowing this ... and not having access to a hydraulic pipe bender I had no choice but to buy it ...

fortunately I recently met a fellow prospector with a mig welding plant which he said I can borrow so can take it apart and give it some love :-*
 

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On the nozzels that ive made , I made a cone shaped orfice pointing towards the 2in. , 3 in. line and I guessed about the appropriate size hole for the orfice opening. BUT I had a big enough pump to supply the water needed to create good enough suction. Its always better to ask than to guess like I try to do! :) Knowing the formula to achieve the correct opening for your pump is even better!
 

Millz90 said:
Hey guys....I'm trying to figure out a way to test my 2" dredge and validate if it has the max amount of suction I should be getting.

Is there anyway to test it?

I am running a harbor freight 6.5 horsepower, 150 gph motor that when running doesn't seem very strong at all.

My hardware is one of those 'Y' that the out of the water pump runs into and then the box, and the 10' or so of the actual 2" sucking hose.

It just seems like I should be sucking/processing up WAY more dirt then I am but maybe I just have higher expectations then I should since I have never seen or used a different dredge.

Which is why I'm wondering if there is a way to test the suction to see if I am getting enough.
Is there a way to increase the amount of suction power with the equipment i currently have?

Any help would be appreciated
Click to expand...

First of all it would help to have a photo of your equipment so we could see exactly what you are working with.

Second a 2" dredge is not going to move an abundance of material. (at max approx 1/2 yard per hour)

There are always ways to increase your suction power by fine tuning the venturi, adding more horsepower, going to a high pressure pump vs a low pressure pump, shortening the hose, reducing the amount of head lift, etc.

If you can place your hand up against the nozzle at the end of the hose and the suction holds it there without the weight of the hose pulling it loose while you're under water, then that's about the most you can expect with the pump you have.

GG~
 

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wrong post sorry
 

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