What to power my small experimental electric dredge with? (updated)

I'm simply trying to get some good vacuum going in a 1 1/4" or 1 1/2" pvc pipe (3 ft long).  I tried hooking up (4) 1200 gph bilge pumps routed into a power jet but it didn't get much suction going.  I'm powering this with 1 or 2 12v car batteries.  

Thanks

Bilge pumps will NOT work no matter how you try. They are volume pumps only and the second you load them with pressure they cavitate and stop pumping.  You will need some small high pressure pumps. for 1 1/4 you will need to run 2 of these 94639 pumps from Harbor Freight. they are 50 PSI 250 GPH. One pump will have the pressure but not enough volume for 1 1/4" suction setup. That is why you will need 2 pumps. The jet nozzle high pressure hole needs to be 3/16" for each pump. This is where the water exits into the 1 1/4" suction nozzle or jet tube arrangement. Now if you plumb the 2 pumps together and want only 1 spray into your suction or jet tube then increase the hole to 1/4" for the combined pumps. Make sure you use at least 5/8" ID hose from the pump to the nozzle anything smaller really drops the volume of the pump/pumps. They operate well on 12 volt deep cycles and long as you keep the dirt from going up the pump will last a very very long time. But you must keep out the dirt. You can't get the pump online only in the store. Make sure you get the high pressure pump and not the 10 psi pump that looks exactly the same as the high pressure one. The 10 psi will not work.

Much appreciated  




Right now I have the 1 1/2" setup going and was willing to go smaller if I had to.  I'm checking out Harbor Freight.  Maybe 3 or 4 pumps for high performance on the larger pipe?  This is different from a normal dredge/sluice so I can use higher flow. I'm going to assume that I have other options as long as the psi & gph are within correct range.  My mistake was not considering psi.  

Do you think this would work?  Only 35 psi but much higher gph.  Maybe psi is more critical?

http://www.marineboatsupplies.com/flojet-water-system-pump-p-8124.html

Do you think this would work?  Only 35 psi but much higher gph.  Maybe psi is more critical?

http://www.marineboatsupplies.com/flojet-water-system-pump-p-8124.html

The high pressure is key to creating the suction you need, as well as the power to lift it up your hose and into a sluice. The gallon-per-hour is only practical in having the right water flow to allow your sluice riffles to work properly with a certian amount of material that is being moved. A little more research needs to be done here, you will need to calculate how much material you will want to move, and then figure out how large/small you want your sluice riffles to be in order to capture the material properly.  For example, the higher the water volume, the more material it can move over the riffles, hence, you will need bigger riffles to compenstate for the larger flow and to capture your heaviest materials properly, without overloading.  A good way to get a rough idea on what you need in your sluice is to take a look at all the different size dredges out there and measure the riffle size and also count the number of riffles in a sluice as well as how far apart they are and how long and wide the sluice box is that is holding those riffles.  A short cut to all of this is to just find a system that already works, pick out the size/powe that you want and duplicate it with what you can get ahold of.

I hope this helps you.

Are you using venturi suction?

That can change the equation for what you need for a pump.


B

Do you think this would work?  Only 35 psi but much higher gph.  Maybe psi is more critical?

http://www.marineboatsupplies.com/flojet-water-system-pump-p-8124.html

The high pressure is key to creating the suction you need, as well as the power to lift it up your hose and into a sluice. The gallon-per-hour is only practical in having the right water flow to allow your sluice riffles to work properly with a certian amount of material that is being moved. A little more research needs to be done here, you will need to calculate how much material you will want to move, and then figure out how large/small you want your sluice riffles to be in order to capture the material properly.  For example, the higher the water volume, the more material it can move over the riffles, hence, you will need bigger riffles to compenstate for the larger flow and to capture your heaviest materials properly, without overloading.  A good way to get a rough idea on what you need in your sluice is to take a look at all the different size dredges out there and measure the riffle size and also count the number of riffles in a sluice as well as how far apart they are and how long and wide the sluice box is that is holding those riffles.  A short cut to all of this is to just find a system that already works, pick out the size/powe that you want and duplicate it with what you can get ahold of.

I hope this helps you.

Thanks.

Are you using venturi suction?

That can change the equation for what you need for a pump.


B

No just a power jet curved into a pvc pipe.

I'm going to get 3 - 4 of the ones mentioned in post #2.  $50 each locally.

golddredgegold,has it dialed in .he knows how to do it!

golddredgegold,has it dialed in .he knows how to do it!

Thanks strickman

Silver and friends,
I have allot and I mean allot of effort into the electric dredge testing. I have tried many many pumps. Even 110 volt pumps with inverters to use them out in the woods with no generator. The ONLY pumps that will work and give you the run time are the Harbor pumps. There is another pump out there that is the exact same pump but under a fancy name and they are getting 300.00 for it. I have sat back and watched guys read way more into this whole thing trying to find pumps other than the one I mention but trust me they are just not out there. Don't get me wrong there is some pricey very very nice pumps but most are 110 volt or 220 and they eat power like crazy there is no way you could keep up with the power consumption like they need. You might as well go gas. I have built many small units and at this time small is the only electric you will see. 3/4" through 1 1/2" is about the biggest you will get going electric. They work great for crevising in small creeks and are silent. I will post a whole article after X-Mas when I return home from my folks. Lots to learn there for those that are interested. As for the sluice box it will need to be small 1/4" riffles and or just a nice expanded metal is more than enough. Another alternative to making a sluice is to just pump the dirt right into a bucket, drill a hole in the side of the 5 gallon bucket and run the tailings right into it. Then run those through a sluice in the creek. Next is to just run the hose from your suction nozzle straight into the mouth of the sluice that is in the creek with the water from the creek already doing the work in the sluice box. This methed works best for me. I just set my sluice up in the creek like I normally would with good water flow just the same as you would now shovel dirt into it but then just attach the hose from your mini electric in the side of the mouth of the sluice and presto a box that you know will catch the gold and you can shovel and suck dirt through it. Like I say I have pics and a pile of reference material on this but I am leaving tomorrow for the holidays so I won't be able to share it till I return.

Merry X-mas guys!

looking foward to it-----and meery CHRISTmas

I noticed on your box it's 100w.  I saw elsewhere the same pump, same specs, except it's 300w.

I can get 4 300w for $50 ea.

That's 1200 watts from your 12 volt battery, so you are looking at less than 60 minutes of run time on a fully charged 105ah battery.

That's 1200 watts from your 12 volt battery, so you are looking at less than 60 minutes of run time on a fully charged 105ah battery.

I'd be thrilled with 60 minutes from a battery.  Is that possible?

I can use 4 car batteries if I have to.  Not a concern.

That's 1200 watts from your 12 volt battery, so you are looking at less than 60 minutes of run time on a fully charged 105ah battery.

             I did that same scenario a while back for someone else . The exception was that it was for a pot to melt lead for reloading in a remote location . I believe I worked it out to 36 minutes .You are pulling 100 amps from a battery that is designed to give 5 amps . If you could do it at 5 amps you would get 21 hours from the 105 AH battery . Whenever you try to pull too much you shorten your time in an inverted or reverse exponential fashion .Imagine having a funnel with a half inch hole on top and you are emptying a 5 gallon bucket through it as fast as you can . The loss will be tremendous . Whereas if you go slowly you can get a lot more water through it albeit in a much longer time frame . The electric dredge has been engineered to death without a clear answer . At the 36 minute timeframe and the use of 4 batteries giving you a HOPEFUL 144 minute work time you must ask "Is it worth it"? You would be better served by working water with less overburden and diving with an underwater MD . If you are working your own claim then perhaps absentee riffles would be called for . In that case you are NOT dredging , you are operating very quietly and you can stay for days unnoticed .Good luck .

Bilge pumps will NOT work no matter how you try. They are volume pumps only and the second you load them with pressure they cavitate and stop pumping.  You will need some small high pressure pumps. for 1 1/4 you will need to run 2 of these 94639 pumps from Harbor Freight. they are 50 PSI 250 GPH. One pump will have the pressure but not enough volume for 1 1/4" suction setup. That is why you will need 2 pumps. The jet nozzle high pressure hole needs to be 3/16" for each pump. This is where the water exits into the 1 1/4" suction nozzle or jet tube arrangement. Now if you plumb the 2 pumps together and want only 1 spray into your suction or jet tube then increase the hole to 1/4" for the combined pumps. Make sure you use at least 5/8" ID hose from the pump to the nozzle anything smaller really drops the volume of the pump/pumps. They operate well on 12 volt deep cycles and long as you keep the dirt from going up the pump will last a very very long time. But you must keep out the dirt. You can't get the pump online only in the store. Make sure you get the high pressure pump and not the 10 psi pump that looks exactly the same as the high pressure one. The 10 psi will not work.

I picked up 4 of the 50 psi pumps.  Thanks.

Do you know the correct diameter of the jet pipe for a 1 1/2" 3 ft pvc pipe with 4 pumps.  I'll use just 3 if 4 is too much.  I am NOT using a sluice box but a different kind of custom trap and I can use higher pressure for stronger vacuum.

I figure Pi x radius squared x 4 ??  sound about right?

Silversleuth, Ever get your dredge going? How did it work? Jimmygoat

Silversleuth, Ever get your dredge going? How did it work? Jimmygoat

Still working on it.

I've calculated the proper jet size as 3/8" for (4) pumps w/ 1 1/2" dredge.

ss,what kind of different trap are you going to use?

ss,what kind of different trap are you going to use?

An experimental one that is not being used for placer gold prospecting.  Maybe someday I'll post a summary of it.