2" Dredge Suction

[spaghettigold]

maybe its because of how powerjets and the flares are built?Are hose connections airtight?Also if the power jet and flare are in a horizontal position ,does it create a air stream backpressure going back over the watersurface in the flare til it reaches the jet ,creating a vacuum cleaner ,loosing water prime with following jet water shooting out of flare.In this case going more vertical with jet and flare (raising the flare outlet)could help,with the cost of some psi. ??
Found this vid,he has power jet out of the water,with a steep jet flare setting.

 

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[Goodyguy]

maybe its because of how powerjets and the flares are built?Are hose connections airtight?Also if the power jet and flare are in a horizontal position ,does it create a air stream backpressure going back over the watersurface in the flare til it reaches the jet ,creating a vacuum cleaner ,loosing water prime with following jet water shooting out of flare.In this case going more vertical with jet and flare (raising the flare outlet)could help,with the cost of some psi. ??
Found this vid,he has power jet out of the water,with a steep jet flare setting.

Seeing is believing!

 

[spaghettigold]

 

[rivets]

The likely reason is the angle of the power jet pipe which just so happens to be submerged ...

For example if you have in the past had it running flat it would then be above the water line and it is this lack of gradient that would impair performance due to the degree parameters of the suction hose ... understanding that this is not to be confused with what I have said thus far because I assume the pumps you used when you had this problem had the PSI to deliver the GPM to the venturi orifice ...


I mean no offence to you by using this word misconception ... but if anyone thinks that submerging a venturi in a few feet of water has an effect on the velocity of flow of liquid within it is in ... and also my comments are aimed at Millz90's specific problems ... who's pump lacks in PSI and obviously did not match it to his venturi ... regardless of the fact its also the wrong configuration for the task at hand

 

[rivets]

If a power jet is in a horizontal position/ flat the parameters of the suction hose are compromised for various reasons ... one of which ... in this case... when the suction hose bends up out of the water the water within it will have a greater surface area and add this to the fact the jet of water has less resistance thus blowing out the exit of its pipe (by this I mean separation of volume into droplets/vapor ) no push + no pull = no suction

 

[spaghettigold]

hi rivets
You seem to have knowledge in hydraulics and stuff. i,m not much into mathematics.Have some questions about gravity sluicing but will start another thread cause it,s not my intention to highjack Millz 90 topic.

 

[rivets]

Hi spaghetti


seem excellent word choice

Truth be told I am brand spanking new to prospecting ... I joined the forum so I could open posters profile's so it would be more time efficient to learn from seasoned prospectors ....



However being a humble plumber by trade ( turned prospector ) I understand many technical things associated with certain aspects of how water is used in gold recovery ...


Water is an amazing element .... it is a picture of truth ... in the end it finds its way back home

 

[spaghettigold]

plumber is a good basic for prospecting gear.

cheers ,Emilio

 

[Timberdoodle]

My recommendation to install 4-5ft of hose after the jet is to maintain a volume of water after the jet to resist the "blast-out" effect which commonly occurs when air enters the system or on initial fire up of the pump when the jet is not primed. This problem is less common on newer dredges with flares that hold enough volume in the flare to resist this effect but it still occurs quite often when working shallows (the rooster tail out of the dredge) Working shallows is the primary reason to go to a suction nozzle so your not having to reprime the jet constantly whenever air enters the system. By installing the extra hose between the jet and sluice and keeping the jet submerged will allow the jet to quickly reprime on its own without the user needing to block the jet outlet to regain prime (although it may take a few seconds). It's the simplest way I know to convert a dredge for operation in areas with shallows without having to purchase a separate suction nozzle and pressure hose. I believe this to be Millz's main issue at this time with the limited information I have from the video. Let's see if he reports back on any testing. I do think his PSI on that pump is limited, but from what I saw his lift was only 12-18" above the water and he should still be getting decent suction running around 25-30psi running pressure.

 

[rivets]

Timberdoodle


Agreed ... we can only assume what the specific problem Millz90 is having and give suggestions on the information he has given ... and I am of the perception English is not his native tongue which enters the equation ...


I am interested what particle size the pump tolerates as this could be the factor coupled with his venturi design with relation to its orifice size and given he said at one point he had suck and at another point did not ... which would imply that he may be on his limit ... but any sharp curve to the suction hose throws him off

 

[Millz90]

here is another question.....

So the OUT of the pump is 2" but I have that reduced down to a 1 1/2" connector connecting to a 1 1/2" tube.....is that correct of should I have the reducer at the jet instead? basically reversing where it gets smaller......?

 

[Millz90]

Timberdoodle


Agreed ... we can only assume what the specific problem Millz90 is having and give suggestions on the information he has given ... and I am of the perception English is not his native tongue which enters the equation ...


I am interested what particle size the pump tolerates as this could be the factor coupled with his venturi design with relation to its orifice size and given he said at one point he had suck and at another point did not ... which would imply that he may be on his limit ... but any sharp curve to the suction hose throws him off

You don't think I speak English? Pretty sure im an American and speak English...lol

I listed the pump specs at the begin of the thread......when you say particle size....are you talking about the size of rocks it will suck up?

And yes, I feel like one set up I had the suction was better than others......

 

[rivets]

In addition to your PM I replied to ...


Without going into the history of confusion of the various pipe threads and their adaption to pipe


Never restrict at the outlet of a pump .... you having done so have reduced your already weak PSI .... and as you are already bordering on the amount you need for your venturi effect ... go buy some 2" 150 PSI pipe and find fittings that will bring the face of this pipe as close to the jet connection thread ... THEN TEST


Particle size is the pumps tolerance ... larger the particle size ... less pressure .... if English be your native tongue ... try reading it

 

[Timberdoodle]

I don't think you are going to improve PSI enough by increasing the hose size to make any difference in this setup. Millz is only running a 2" jet which should only be using around 60gpm or so and a 1.5" pressure hose will handle this flow rate with very little loss. Necking down at the pump end can actually be beneficial and improve pump performance depending on flow requirements. I just don't see any benefits over his existing setup if all components (jet etc..) are built correctly. Millz- can you provide a better pic of the jet and a measurement of the jet orifice?

 

[rivets]

Timber

"Necking down at the pump end can actually be beneficial and improve pump performance depending on flow requirements"


Friction ... has a negative effect both on PSI and GPM ... and seeing a pumps performance is measured by the GPM and PSI it delivers ... so any restrictions in pipework are of no benefit to performance ... unless one wants to cut back performance ... which in this case ... is not the case

 

[Millz90]

.... if English be your native tongue ... try reading it

Dude, don't be a dick!? Why do you have to go there? I won’t mention your awesome typing and sentence ability either. This is a place to talk and learn not a place to criticize. Just because you know about dredges and pumps doesn't mean you’re a genius so slow down. Don't reply to my thread if you’re not a fan of my ability to speak.

anyway.....

 

[Millz90]

I don't think you are going to improve PSI enough by increasing the hose size to make any difference in this setup. Millz is only running a 2" jet which should only be using around 60gpm or so and a 1.5" pressure hose will handle this flow rate with very little loss. Necking down at the pump end can actually be beneficial and improve pump performance depending on flow requirements. I just don't see any benefits over his existing setup if all components (jet etc..) are built correctly. Millz- can you provide a better pic of the jet and a measurement of the jet orifice?

Sure I will take some pictures tonight and post them.

 

[Timberdoodle]

Timber

"Necking down at the pump end can actually be beneficial and improve pump performance depending on flow requirements"


Friction ... has a negative effect both on PSI and GPM ... and seeing a pumps performance is measured by the GPM and PSI it delivers ... so any restrictions in pipework are of no benefit to performance ... unless one wants to cut back performance ... which in this case ... is not the case

In this case the 60gpm requirement means a flow speed of 11fps on 10ft of 1.5" of line. No major friction losses to consider. Spending an extra $50-100 on new 2" line and fittings to gain maybe an additional 1psi is not going to help the operation, just cost more.
Necking down a centrifugal pump can help a pump run closer to it's BEP and his 6.5hp pump is overkill on gpm delivery for a 2" dredge so providing less gpm by necking it down is not going to be a problem. The only issue would be if it was necked down too far and flow speeds increased to the point friction losses starting becoming a problem.

 

[rivets]

I did not say you can not read ... its just become blatantly obvious that you do not practice it .... and it is for this reason that you have the wrong pump and the wrong dredge configuration ..... and so if my words appear to be cruel ... its just me being kind

 

[rivets]

Timber


Not that it matters .... If I were in a predicament ... I would give this a go ... throttle the inlet ( thus causing more pressure at the eye ) .... run pump at low revs as possible ... and go with 2" to the jet ....


Anyway ..... "One can not make a silk purse out of a sow's ear" .... or two sow' ears in Millz90's case