Compressed air powered vacuum generators (Air-vac)... any experience?

[Dadnatron]

I'm looking at building a 'home version' of an Air-spade to do bare root transplantation of trees on my property. I think I've a design which will work just fine. However, I see the utility in adding a Vacuum to the process to maintain the soil in a usable form to reset the tree. These are available commercially, but they seem pretty darned expensive for what you actually get.

Does anyone have any experience with a Compressed Air vacuum generator (in a vacuum dirt off the ground) sort of process? I know they use them as a major mover in manufacturing, but I can't find much on just picking up dirt. The ones which are commercially available are just too expensive to be realistic. And I'm thinking about building a 3pt hitch version and just purchasing or perhaps even building, my own vacuum generator head.

I have some questions that I'd like to ask if anyone has experience.

 

[Dadnatron]

 

[4570Man]

What kind of air compressor do you have? A shop vac with a separator seems like a more cost effective solution.

 

[Dadnatron]

I don't have a compressor at this point. I can rent one to insure everything I build works and depending upon how often I need it. I've looked at purchasing a 185cfm (which apparently is what runs most of these vacuums/air spades) and have it for other things such as fence building etc. But right now, I'm still in the 'will it work and if so, how do I do it' stage.

But, this would be based off of at least 185cfm at 90-110psi.

 

[4570Man]

I've seen several old air compressors that used an engine only firing on 1/2 the cylinders. The others served as an air compressor. That should be a pretty cheap option.

 

[MossRoad]

There's a bunch of videos on them on youtube.

 

[Dadnatron]

There's a bunch of videos on them on youtube.

I see them and understand how they work, in general. I'm trying to learn the physics a little better and determine whether I can build a larger tank (such as refab a household propane tank) into something which will hold more dirt. In my mind, a venturi suction head for a 55gal barrel should be able to achieve the same degree of suction in a larger tank. It will take longer to achieve the same degree of suction, given the larger volume of air which much be evacuated prior to max vacuum, but it seems that it should work.

I am thinking about cutting a 'trap door' into a vertically oriented propane tank for evacuation of material. I'm also playing with the thought that I could add a 'stirring' mechanism inside which would allow me to add water to make a slurry. Apparently, when replanting, you get a better % success by using a 'mud slurry' to insure there aren't a lot of air pockets.

The water/slurry is just a thought however. But I know I'll need more than 55gal capacity and I don't want to be manhandling a full 55gal barrel anyway. A tank on a 3pt could be moved around easily and carry much more.

 

[SPYDERLK]

I see them and understand how they work, in general. I'm trying to learn the physics a little better and determine whether I can build a larger tank (such as refab a household propane tank) into something which will hold more dirt. In my mind, a venturi suction head for a 55gal barrel should be able to achieve the same degree of suction in a larger tank. It will take longer to achieve the same degree of suction, given the larger volume of air which much be evacuated prior to max vacuum, but it seems that it should work.

I am thinking about cutting a 'trap door' into a vertically oriented propane tank for evacuation of material. I'm also playing with the thought that I could add a 'stirring' mechanism inside which would allow me to add water to make a slurry. Apparently, when replanting, you get a better % success by using a 'mud slurry' to insure there aren't a lot of air pockets.

The water/slurry is just a thought however. But I know I'll need more than 55gal capacity and I don't want to be manhandling a full 55gal barrel anyway. A tank on a 3pt could be moved around easily and carry much more.

I think you have it down pretty well​

The main attraction I see with air powered is the higher vacuum level they typically achieve over a high volume centrifugal mechanical vacuum. My USATCO handheld air vac will do about 7 feet of water static. I believe shopvacs top out at about 2 feet. Air volume [suction CFM] per HP is better with the mechanical though. -- So for steady state sucking the mechanical will win out. But if a stored vacuum vessel is employed, even a relatively small air eductor vac would temporarily give the powerful superior suction needed to readily lift dirt. It would take a pretty big tank to provide long enough vacuum bursts unless you employ a large eductor.. Superior but requires lots of compressor power.

 

[Dadnatron]

Spyder, the reason I want to use Air vacuum generator rather than a rotary pump is simply because I need to maintain the vacuum for a long period of time. Not to simply generate it in a single shot, then use it out in the field.

I will have a large CFM air compressor for the Air-spade aspect. I thought I could just switch the air over to the tank to power the vacuum. Otherwise, I could build a PTO powered vac, but that seems more complicated than simply adding a Air Powered vacuum generator to a tank. I see in the videos above, that those generators can build and maintain the suction required to pull soil and rock out of a hole. And there is no moving parts other than a valve to close the air off.

 

[cqaigy2]

I've never seen the air drilling before.

I've used one mounted on a truck, like a septic sucking vacuum. The drilling was a water jet and you got wet and wanted to use some sort of face protection.