Windmill powered air pump....

NM_Shooter · October 11, 2008, 11:31:39 PM

Okay, Here's a question that is from left field.

I'm trying to figure out a way to build a cheap windmill powered air pump to aerate a trout pond during the winter. They can be had for about $1k, but I am cheap and like to try and build stuff on my own.

I'm thinking I can use a small gas engine as the air pump. I know it can be done with a four stroke engine, but can I drive a small two stroke (left over weed wacker engine) to do the same thing?

I need some hillbilly engineering on this.

Thanks,

-f-

glenn kangiser · October 12, 2008, 12:01:12 AM

I don't see why not, Frank.

Just put a check valve in place of the spark plug. If you can't find the right threads just break the porcelain out of the plug and weld or braze a pipe of the desired size on it - maybe 1/4" to 1/2".

Open the carb butterfly and choke to let the air in - use the same air cleaner if you want. The compression stroke should push the air charge through the check valve rather than compressing it...of course the flow is away from the head.

October 12, 2008, 12:05:02 AM

I can find you some plans for blades if you need them.

glenn kangiser · October 12, 2008, 12:07:41 AM

I just came up with a problem, Frank. Lubrication for the 2 stroke is the oil in the gas.

glenn kangiser · October 12, 2008, 12:09:54 AM

How about a scrapped air compressor with a crankcase or an oil-less one?

October 12, 2008, 12:13:01 AM

...or an air brake chamber from a truck with 2 check valves -one in one out on the single opening and make your own crank - mount the crank on pillow blocks. This would make a diaphragm pump.... or similar hooked to a bellows. A crank is easy to make. I can sketch up one like I made for my model steam engine.

NM_Shooter · October 12, 2008, 09:13:47 AM

I have only a teeny amount of torque for this thing. It appears that the commercial variety of the aerator only has a 1/2" stroke! But the diameter of the cylinder looks to be about 8".

Here is a page that has an exploded diagram: http://www.malibuwater.com/oAirCompressor.html

I was wondering about the cylinder lubrication. I considered using silicon lube (sort of like plumber's lubricant) as it would not be burning off, and the pressure and temperature would be low. I suppose that over time, such as a full winter it might still wear off though.

I saw an interesting technique for making fan blades using large diameter PVC pipe. Is that what you have patterns for?

I had also considered the Savonius (sp?) style turbine, as it is omnidirectional.

What about a smog pump off of a small car?

glenn kangiser · October 12, 2008, 10:28:28 AM

Smog pump could be a possibility. I don't know what pressure they can put out. I think rather than take a chance on the 2 cycle I would go with something else.

You only need .433 lbs pressure per foot of submersion plus a bit to make it break through the static wate so say you get 2 feet of depth per lb of pressure would be good - Actual is 2.31 feet per lb.

I have plans for the green pvc blade and will email them to you. The Savonius rotor is omnidirectional if you make it in 2 levels offset 90 degrees from each other otherwise there are a couple of dead spots on the sides.

Here is a savonius generator link for a small one. http://www.homesopen.com/wind/savonius.pdf

glenn kangiser · October 12, 2008, 10:37:09 AM

Check you email you listed here on the forum - should be there. Let me know if it made it - I have to work today.

October 12, 2008, 04:57:32 PM

Well, you gotta love Craigslist. I posted a request for an old air-less compressor, looking for a junk one. Guy just emailed and said he has one I can have. Part of the control housing got crushed in a move, but the motor and pump worked before the move.

Got the plans Glen... thanks for the help. I needed a fun winter project!

-f-

NM_Shooter · October 12, 2008, 10:32:48 PM

Okay.. picked up the compressor a while ago. Curiosity got the better of me and I decided to start the dissection. Grabbed a beer and went out to the garage.

Here is the sacrificial lamb before the operation. A few spins on the rotor provided me with some tiny puffs of air. I guess if you get tiny puffs of air 1700 times a minute it all adds up.

I made good use of my multi-function pry / chisel / tool, and my multi purpose wood handled impact generator, and voila. Interesting design for the cylinder head. It appears to have a set of reed valves built into the head.

The motor shaft is pressed into the bearings. I gave it a tap with my multi purpose wood handled impact generator, and it was not going to budge. I have a buddy with a machine shop that I will enlist to see if he can separate that shaft from the bearing, and maybe press on a couple of new bearings for me.

As if I don't have anything else to do. Oh well, it beats watching TV.

Redoverfarm · October 12, 2008, 10:36:51 PM

Frank I sent you a PM on the subject.

glenn kangiser · October 12, 2008, 11:00:09 PM

Looks like fun, Frank. I have a few projects like that to do too. Like making a wind generator out of a treadmill PM motor.

Damon · August 19, 2009, 01:42:56 PM

Newbie here and found the forum specifically because of this thread. I was wondering if the project made any more progress or if anyone had any other tips? I'm trying to find a cheap air pump that could produce around 4CFM at 10psi. I don't know if an oil-less compressor would have enough flow or if I should look at the bellows-type pumps that supposedly can be built out of semi truck suspensions. I have a 1 acre pond that is in DESPERATE need of an aerator and don't want the recurring costs of an electric aerator.

August 19, 2009, 02:37:38 PM

Oiless compressors, as any other, all have their rated capacity for the CFM. They all vary and of course are rated at a certain RPM. I believe most (all?) oiless have very a fairly small capacity per stroke or revolution. Therefore I think they would have to have a high rate of speed to be of any use.

A bellows might be a better bet for the maybe slower windmill speeds and the variability of wind speed. That does depend on what sort o wind weather you have though. Some places have more, some like mine are low speed mostly.

I wonder how an old piston type auto A?C compressor would work? We use them for pumping air for tires on our 4x4's/ Some also use the rotary type A?C compresors though with them you have to oil them and remove the oil from the output air. The old piston types have their own crankcase and oil so don't experience that problem.

peternap · August 19, 2009, 06:12:03 PM

I had a little different take on it. The Mennonite windmills have an eccentric at the back and it raises and lowers a rod that goes to the ground (In their case to pump water). Why not just take a large pipe, fit it with a check valve, make a piston to connect to the rod and reduce the other end of the pipe with a discharge fitting.

MountainDon · August 19, 2009, 06:32:54 PM

That sounds like a

method that should work fine, Peter. Less messing around than with compressors, etc.

glenn kangiser · August 19, 2009, 11:30:18 PM

I think truck air brake pots could be used as a diaphragm pump with a simple crank or maybe an added pitman arm and a couple check or flapper valves. Blades can be made from the green pvc water pipe - maybe 6 to 12 inch dia. Many times there are pieces left on construction sites that can be had for the asking.

Seems like 10 psi is overkill - that would go to 23.1 feet deep - seems less would work.

Damon · August 20, 2009, 12:35:14 PM

My concern with the "Mennonite" approach is maintenance and durability. You're talking about a lot of friction over the years, replacing seals, etc. The AC compressor idea is intriguing but you'd have to make sure there was no chance of oil entering the discharge hose. Pumping any oil into my pond will make the largemouth and crappie VERY unhappy.

10psi is indeed overkill. I found a formula of 2.1 feet of depth per PSI. My pond is 12' at the deepest and most of it is only 3'. For 12' I'd need just under 6psi.

The bellows would not provide a constant air flow but I'm still thinking it may be the best route. I can't seem to find an appropriate rotary high volume/low pressure compressor.

Damon · August 21, 2009, 10:52:22 AM

Also, I discovered that rotary vane pumps only produce pressure when spun to a certain RPM, usually 2000+. My RPM will depend entirely on the windspeed so I think a bellows or piston style would be better. I spent some time on the phone with GAST pumps who makes compressors and they have a unit that produces 4.2 CFM at 6psi and 1500rpm... but it's $540. You can buy an entire bellows unit with shaft for less than price. See here... http://www.pondaeration.com/Universal%20Parts.html These are the parts for an American Eagle Windmill Aerator. I'm looking to DIY for much cheaper.

The only problem I see with the bellows style is that it cycles, just like a piston pump would. The airflow is not constant. Check out 2:25 into this video of the American Eagle unit... http://www.youtube.com/watch?v=p82ufI9LZYg

I'm envisioning a bellows system with one on each side of the crankshaft. When one is on the exhaust stroke the other would be on the intake. You'd got twice as much airflow with half as much delay. It would create more resistance on the shaft and the windmill would need more wind/torque to spin a dual bellows setup. Any thoughts?

August 21, 2009, 04:28:02 PM

That's the way water powered bellows for our local iron furnaces worked, twin bellows so that the air supply was almost constant. Is there outflow from the pond and some drop? The weight of water and gravity are maybe more powerful.

Damon · August 21, 2009, 05:15:54 PM

The pond is spring fed and produces a small stream running down to a retention area ~500' away and 6' lower. I don't think that's enough head to work with. Plus, it dries up from June-Oct when I really need the aeration to prevent weed and algae growth.

glenn kangiser · August 21, 2009, 10:22:29 PM

Quote from: Damon on August 21, 2009, 10:52:22 AM
Also, I discovered that rotary vane pumps only produce pressure when spun to a certain RPM, usually 2000+. My RPM will depend entirely on the windspeed so I think a bellows or piston style would be better. I spent some time on the phone with GAST pumps who makes compressors and they have a unit that produces 4.2 CFM at 6psi and 1500rpm... but it's $540. You can buy an entire bellows unit with shaft for less than price. See here... http://www.pondaeration.com/Universal%20Parts.html These are the parts for an American Eagle Windmill Aerator. I'm looking to DIY for much cheaper.

The only problem I see with the bellows style is that it cycles, just like a piston pump would. The airflow is not constant. Check out 2:25 into this video of the American Eagle unit... http://www.youtube.com/watch?v=p82ufI9LZYg

I'm envisioning a bellows system with one on each side of the crankshaft. When one is on the exhaust stroke the other would be on the intake. You'd got twice as much airflow with half as much delay. It would create more resistance on the shaft and the windmill would need more wind/torque to spin a dual bellows setup. Any thoughts?

Yeah - I think you see ...

A double would be much more constant or maybe a custom single with air taken from both sides of the diaphragm.

Damon · August 24, 2009, 12:37:45 PM

Has anyone actually seen a truck air bag suspension up close?

From what I can tell, there's threaded holes on the top and bottom for mounting, and a single opening into the interior. So air must go in and out of the same opening. I assume you'd attach a 'Y' onto the opening and then put a pair of check valves on so your airflow goes in one direction. I was looking at the American Eagle parts page and trying to figure out this picture...

I figured there was an eccentric lobe that compressed the airbag but it looked like that far bearing is attached to the top of the bag. How does it pump?! The shaft didn't look straight and in one of the videos they show another view of the crankshaft. It looks like after that middle bearing the drive shaft ends and a pumping shaft is welded to the SIDE of the drive shaft. The pump shaft then revolves around the center axis, so when its attached to the bellows, they go up and down (and a little side to side I guess?) Not exactly how I figured it worked but maybe it cuts down on wear and tear if you had a lobe. You could still use this design with dual bellows. At first I thought having two might make the driveshaft harder to turn. But since one bellows would be filling while the other is compressing wouldn't it actually require less torque?

glenn kangiser · August 24, 2009, 09:54:23 PM

That shaft is cut and offset to pump the bellows - just a crankshaft with two bearings on this end - one behind the red plate and one on top of the air bag. Then there would be just one check valve for air in and one for air out.

My old Peterbilt had airbags.