Barrels in fast water

Timberdoodle said:
Omni, I think I understand where your coming from on this. The ability to process material properly in a sluice is dependent on the slurry ratio and the velocity of the water through the sluice in conjunction with the riffle design. So if we look at a standard dredge, we have much more water than slurry under normal operating conditions than we truly need to process the material properly, therefore the box is designed for a width that provides the flow velocity and depth to run properly and move large material through.

If you use a more efficient jet which can produce the same suction as another Jet while being made or adjusted with a smaller orifice, the results will provide the same suction you need with less water being added though the jet. So the overall volume of water being delivered to the sluice is reduced by the amount of less water required to create the desired suction level.

What we do with this is how I differ in view from existing designs. Since the slurry/water ratio is already enough to process the material properly, I would build the flare and sluicebox sized appropriately to maintain the velocity of flow and depth to keep the material moving through. We must understand that the water supplied by the jet is not really needed to process the material properly since the slurry ratio is determined at the suction hose. The box size on a log jet design is larger than it needs to be to incorporate the added water from the jet and maintain flow velocity and depth.

This is being practiced already by anyone who is using a more efficient jet than a log jet. You have more water from suction than from the jet and you set the motor for sluice operation/depth. You don't run your motor at the same speed that you ran a log jet because it would result in overloading the box and increasing the flow velocity beyond recommended rates. In this case you would want to install a larger box to handle more water/material if you wanted to crank it up.
Click to expand...

But you did not address the set volume of water/slurry.
"If a hose (don't know any numbers, just pulling this out of my ass) will hold 1/2 cubic foot of water for a 6"x1' section of hose, you apply a force to cause a flow (venture) that hose will still only hold that volume of water. The hose doesn't expand nor contract and neither does the water."
"
Once flow is started the only thing that can change is the velocity, water doesn't expand/contract, neither does the hose. If you jet is only supplying 250gpm of flow lets say in 1 second that's 2 cups of water. Lets break the 1/2 cubic foot of water down to cups. That's 59.85 rounded. So being water cant compress under these conditions, we are adding 2 cups of water so we much take away 2 cups of water. Do we still not end up with 59.85 cups? We're talking in a ideal condition the system is airtight or underwater and only sucking in minute quantities of water to fill in air gaps. So the only variable here is velocity. You cant cram 1.2 gallons of water into a 1 gallon can. See where I'm going with this>? Your velocity will (increase) due to more efficient push? (1 hand vrs 2 hands) Or is it going to decrease being you have a fixed volume of water and your adding and taking away. This is the part that I am unsure of, but logic tells me it will increase due to more efficient push. My point is I do not see how you are going to have less unless the velocity decreases because your volume can't change unless you create a "void"".

What I'm trying to get at is, does the slurry, speed up, slow down or have no change. I know the amount of slurry coming to the jet is fixed.(the hose only holds so much {1.2 gallons wont fit in 1 gallon container}so some of that slurry must be displaced (accelerated forward from the venture blast) but the volume per cubic inch of the hose remains the same. It just wont hold more because nothing expands or contracts. Do you follow? The only real change I see is velocity. Being slurry is being displaced by water from the jet, that void is being filled by water from the jet. Correct? The slurry after the jet would speed up while the slurry behind (slows down?) (speeds up) I don't know that part. But I know the VOLUME will always remain the same. That's why I don't see why you say you would have less volume across the box when nothing but the speed changes.
Please enlighten me as I want to know how you get less when the volume remains the same.
Hope you understand as I may not be articulating well what I'm asking.
I have nothing but respect for you as you know way more then me when it comes to this subject.
 

I'm really sorry that this whole discussion is kind of being warped. It's not my intention.
Disclaimer"
I don't even want to pretend for a minute that I'm a expert nor do I know anything about jets. I'm learning and what I post is either what I have read/learned and or used my logic.
Sorry if this has caused this thread to start blowing up and getting feathers ruffled.

P, I wasn't trying to make a personal attack on you. I have traveled all over the world, seen things people would not believe. But the one common thing I see everywhere including here is people don't want to have to work hard. Some do, some have great work ethics. Like my old man used to say, "If you want something bad enough, work your ass off to get it."
With that being said, I've seen it in the Philippines, Taiwan, Korea, England, Russia...to many places to name, but people are lazy and don't want to work hard. To hear you say you can't or don't want to, blah blah, It really makes my point. If you really want something, it's not going to be given to you, you have to make it happen. Find a way and if that doesn't work then invent something that will make it happen. Spending hard earned money to build a 6" dredge and cheeping out on a engine pump because it weights more, and is only going to process a little more then a 4 doesn't make sense. If you read my last 2 post, I make a very good (imo) point about volume not changing, but haven't received an answer yet that satisfies me.
 

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G1sammons said:
No1 we don't need a certain ratio to process material anywhere but the box ! No2 we didn't make a jet improvement to do the same thing it was to do more not the same ! These 2 simple fact is where you keep going wrong , the entire objective is to create as much suction / water flow as possible with your pump and engine and jet and from there we build a box to process that amount ! What your trying to do is make engine pump and jet combo process less and build a box to make it process proper ..

The only advantage to this is a lighter box and engine and what everyone has been saying is if that's what your after then run a 4". And make it flow more with a better jet and adjust your box to deal with it!
Click to expand...

This discussion is interesting for sure.

Let's look at your current problem with your 6". You do not have enough water flow depth/velocity to clear the box.
Your choices are 1. Make a smaller box that will properly operate to match your volume (you would not be processing less, but processing properly)
2. Install a more efficient jet with your existing pump to get more suction volume to clear the box. (this would mean less pump volume vs suction volume)

I fail to see any difference in what I have been explaining. It is simply looking at it from different viewpoints. You want to run more, more, more, if you use a better jet and I am saying you can run the same but with less motor and overall size due to the use of a better jet.
 

omnicron said:
But you did not address the set volume of water/slurry.
"If a hose (don't know any numbers, just pulling this out of my ass) will hold 1/2 cubic foot of water for a 6"x1' section of hose, you apply a force to cause a flow (venture) that hose will still only hold that volume of water. The hose doesn't expand nor contract and neither does the water."
"
Once flow is started the only thing that can change is the velocity, water doesn't expand/contract, neither does the hose. If you jet is only supplying 250gpm of flow lets say in 1 second that's 2 cups of water. Lets break the 1/2 cubic foot of water down to cups. That's 59.85 rounded. So being water cant compress under these conditions, we are adding 2 cups of water so we much take away 2 cups of water. Do we still not end up with 59.85 cups? We're talking in a ideal condition the system is airtight or underwater and only sucking in minute quantities of water to fill in air gaps. So the only variable here is velocity. You cant cram 1.2 gallons of water into a 1 gallon can. See where I'm going with this>? Your velocity will (increase) due to more efficient push? (1 hand vrs 2 hands) Or is it going to decrease being you have a fixed volume of water and your adding and taking away. This is the part that I am unsure of, but logic tells me it will increase due to more efficient push. My point is I do not see how you are going to have less unless the velocity decreases because your volume can't change unless you create a "void"".

What I'm trying to get at is, does the slurry, speed up, slow down or have no change. I know the amount of slurry coming to the jet is fixed.(the hose only holds so much {1.2 gallons wont fit in 1 gallon container}so some of that slurry must be displaced (accelerated forward from the venture blast) but the volume per cubic inch of the hose remains the same. It just wont hold more because nothing expands or contracts. Do you follow? The only real change I see is velocity. Being slurry is being displaced by water from the jet, that void is being filled by water from the jet. Correct? The slurry after the jet would speed up while the slurry behind (slows down?) (speeds up) I don't know that part. But I know the VOLUME will always remain the same. That's why I don't see why you say you would have less volume across the box when nothing but the speed changes.
Please enlighten me as I want to know how you get less when the volume remains the same.
Hope you understand as I may not be articulating well what I'm asking.
I have nothing but respect for you as you know way more then me when it comes to this subject.
Click to expand...

I think you understand a jet fairly well but are possibly getting hung up somewhere.
A jet forces water through the orifice to push on the water column and evacuate the water in the jet. This evacuation causes suction from the hose.
The amount of force applied to the water column is dependent on how the jet is designed and therefore how much vacuum is created is directly related to the force being applied.
The vacuum created is in relation to the velocity the water is moving up suction hose.
A infinity jet for example can apply greater force to the water column to evacuate it than a comparable sized log jet. So water velocity in the suction hose of an infinity jet is greater when the same energy level from a pump is used to drive each jet.
If you built a infinity jet to match the suction/velocity of a comparable log jet. You would find that less volume is required to the jet to produce the suction/hose velocity you are trying to match.
The total volume leaving each jet is thereby different when matching their combined volume(feed and suction) if referencing the same suction level/velocity in the hose.
The velocity at the output of each jet is also different because the log jet uses more water and has to increase to velocity in the output of the jet to "fit" both the suction volume and jet applied volume. So the output of an infinity jet that is designed to match the suction level of a log jet will have the same suction velocity, but have less velocity in the jet outlet since it uses less water to produce the same suction level.
Same hose size outlets with less velocity in the infinity type jet means less total volume supplied to the sluicebox.
I hope I explained it ok.
 

G1sammons said:
no it's not the same !
You want to make a smaller box to correct a problem and I want to increase flow to make it operate correctly .
Your right in part of this there are two way to go about the fix ! But considering that my reason for geting a bigger dredge was to move more material. I prefer to make it do just that. A more efficient jet doesn't mean less pump water it means I can move more water with the same pump.... At the end of my day my money is gona produce more by doing it my way doing it your way still spend the money but no improvement on the production side ! Yes the box would clear but it wount process anymore !
And if your gona spend the money you might as well get something out of it ....
Plus in the mix of the there's some things you don't pick up on ! If your underpowered you much more likely to plug your hose which equals down time to clear it .
Now your production just went down even more ! This is where nozzle time makes a huge difference when you design something ..
I know this from running it not something you pick up on designing and looking at jet flow numbers .. The harder and faster that nozzle pulls the less likely it is to jam up in your hose and jet...

My pointe was never about this anyway . If your purpose is to move more materal why not design your machine to do that !
Why would you back off the the capability with a smaller pump engine and jet combo to move less materal?your talking about a 20lbs to 30lbs difference in weight and 1/2 of your daily production . Where is the seance in that?
Click to expand...

I am not sure if you are reading my posts correctly. I did not say in your case it would be less pump volume. I said less pump volume vs suction volume.
I have said all along that the suction volume/velocity is the same as a log jet. It is not underpowered thereby causing jams etc..you would not find any difference in the suction level.

Why would anyone want to look at this the way I am? Easy to answer-not everyone can use a large dredge or pack one in to remote locations. So if your not a diehard production guy like you are, then the option to move more material with a smaller unit is very appealing. I mainly work smaller streams and some couldn't even fit a 6" dredge within the waterway. By having a 4" dredge that is the size and weight of a 2" dredge means I am moving much more material while carrying in a much smaller and lighter setup and using the same motor and gas consumption of a 2". So in relation I am doing more, more, more than I could using a standard dredge of close proximity in size and weight.
 

I'm still stuck on the volume of the slurry.

When your jet (any kind) hits the slurry the laws of physics dictate that some must be displaced due to the pressure being inducted. (cant fit 1.2 gallons into a 1 gallon container)

Being is a "sealed" system and something is being displaced, you are not creating a void. The water from the jet is filling in this void.

With that said, if you displace 1 cubic inch of slurry your replacing it with 1 cubic of water. Right?

So the volume must remain the same, correct?

If your just replacing slurry with water at the same exchange rate 1:1, I do not see how you would end up with less.

I understand how the venture works, that's part of fluid dynamics that I understand. I understand how the efficiencies of different jets also work also. I also understand how you have to have the right mix for your sluice to work properly.

Make me understand this how your volume/exchange math works out and I'll be good to go! I don't see it if your material/hose neither expands or contracts, it's inside volume stays the same how you can get less.
 

omnicron said:
I'm still stuck on the volume of the slurry.

When your jet (any kind) hits the slurry the laws of physics dictate that some must be displaced due to the pressure being inducted. (cant fit 1.2 gallons into a 1 gallon container)

Being is a "sealed" system and something is being displaced, you are not creating a void. The water from the jet is filling in this void.

With that said, if you displace 1 cubic inch of slurry your replacing it with 1 cubic of water. Right?

So the volume must remain the same, correct?

If your just replacing slurry with water at the same exchange rate 1:1, I do not see how you would end up with less.

I understand how the venture works, that's part of fluid dynamics that I understand. I understand how the efficiencies of different jets also work also. I also understand how you have to have the right mix for your sluice to work properly.

Make me understand this how your volume/exchange math works out and I'll be good to go! I don't see it if your material/hose neither expands or contracts, it's inside volume stays the same how you can get less.
Click to expand...

The difference is how much water volume was used to displace the slurry.
A log jet will run close to 1:1 displacement to suction requiring the outlet of the jet to be 2X the velocity of the suction velocity.
A infinity jet can displace at 1:2 rate or better requiring the outlet of the jet to only be 1.5X the velocity of the suction velocity.
The difference in velocity in the outlet is the difference in total volume to the box. It is a different "exchange rate" using less water for the same effective suction.
 

So the velocity is changing and not the volume?
Still, it should not matter what kind of Jet, standard, tri or infinity is used. The volume of slurry displaced by any jet, regardless, is replaced by water from the jet. Cant fit more the gallon of water into a 1 gallon container. It's impossible for a jet to replace slurry at a exchange rate of anything but a 1:1 ratio. Water isn't compressable and you cant break up atoms in these conditions so how can there be less>? So there should be no difference in VOLUME, just VELOCITY?

If that is the case then as we have been saying, your going backwards and processing less material because you have slowed the velocity down to a un-acceptable level. You can justify building a smaller sluice and say it's going to be more efficient but at the end of the day, a side by side comparison of two 4" dredges side by side one with a regular jet and one with a small engine/pump/infinity jet and sluice box (footprint) I bet the regular sized dredge would move more material because as I understand you, your velocity is changing and not the volume.

As I understand the laws of Physics, every force has a equal and opposite force. When you increase the positive rate of flow (pressure) you have a equal increase in suction. More suction is created by more velocity and that equals more slurry!
Right or wrong? I'm lost!
 

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G1sammons said:
This how your logic looks timber! You want to build a better jet to move more water so you can slow it down to creat a smaller dredge so you don't have to carry the heavy load into the woods!
Would it not be simpler and cheaper to start with a smaller dredge but that better jet on it and work it harder?
Click to expand...

I am not talking about slowing anything down. There are suction velocity requirements needed to move larger material and these HAVE to be met with any equipment or you are going to get frustrated with hose plugs etc.. like you mentioned.

The efficiency of moving less material by hand is one of the most important aspects of increasing dredge size. So it does make sense to go bigger if you can and still meet all the operational requirements of running a dredge properly. Running a smaller dredge would still limit the cobble size and total volume that the sluicebox can handle, so you would want a larger sluicebox if you are going to run full out with a better jet.
 

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