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Pto powered compressor for 300 cfm at 50 psi

paul81

Plastic
Joined
Apr 8, 2014
Location
SW Ont Canada
As the title states, I'm trying to figure out the best way to generate 300 cfm at 50 psi powered by a tractor pto. The application is for cleaning out manure drag hoses by pushing a foam pig through them and also for cleaning off farm machinery.

Cheaper is better as it will likely only see 20 hours of use per year. Smaller is better as well as I'd like to integrate it into another piece of equipment.

Currently I'm using an old 150 hp Sullair rotary screw converted to pto drive. It works well, but is way too big and heavy to mount on anything else.

My thoughts were some kind of vane compressor if I can find one good for 50 psi or even converting an old engine.
 
If cycle time is not a particular issue then I would go with a relatively small, light weight compressor and a good size air storage tank. 300 cfm is a fair amount to maintain.
 
If cycle time is not a particular issue then I would go with a relatively small, light weight compressor and a good size air storage tank. 300 cfm is a fair amount to maintain.

The pig isn't a perfect seal, and once you send it down the line, you need to keep it moving with lots of air behind it.
 
Don't sand haulers use a PTO pump to blow frac sand out of their trucks? That may an industry doing a similar task.

I looked up a site listing frac sand blowers, and it seems most are good to 20 psi, with the odd 25 or 30 psi so not quite enough. The Bowie pumps that were mentioned are strictly liquid pumps.

There are vane compressors out there with the specs I'm looking for, but they seem to be designed for special gas applications (read $$$$) and require external cooling and lubrication systems, so not exactly compact.

Our system came with Champion R70 compressor, but it was hopelessly slow at moving the pig. The R70 is a two stage with a theoretical displacement of 140 CFM at 1000 rpm. I'm wondering if I can do something with it, since we already have it anyways. Here's some ideas I had:
1. Replumb it to be a single stage compressor, ie each cylinder takes in fresh air. The second stage has much smaller pistons so based on the dimensions given in the manual, the theoretical displacement would become 180 CFM, still on the small side.
2. Can a compressor be pressure fed with one of the truck blowers mentioned above? If I only need 50 psi, I would not be overloading the compressor (it's good to 175) but it would be discharging air for much more of the piston stroke.

3. Is it possible to build a venturi style flow multiplier that could still output 50 psi? I'm thinking something like the blow guns with the special tip or a Dyson "bladeless" fan.
 
Take an old engine and spin it with the PTO, probably a 350 chevy.

Plumb the exhaust to your tank.

Probably should advance the cam a couple of teeth to open the exhaust valve
before TDC.

Or just rent the proper tow behind air compressor for the 20 hours each year that you need it.
 
You need a serious compressor, one meant for construction hammers and accessories. These normally require at least 100 HP and I think that may be more than your PTO can handle. I would be looking for a used trailer mounted diesel engine driven compressor. Perhaps even military surplus. Google is your friend.
 
You need a serious compressor, one meant for construction hammers and accessories. These normally require at least 100 HP and I think that may be more than your PTO can handle. I would be looking for a used trailer mounted diesel engine driven compressor. Perhaps even military surplus. Google is your friend.

200 CFM at 120 psi.....Just sayin'.

Many tractors in "The Colonies" have large PTO's
Winco W165FPTOT-18 PTO Generator (165kW)

Please stop assuming.
 

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Well I've already made one dumb ass suggestion so I guess I will try to keep it up. I have a backpack blower that is rated at 756 CFM at 234 MPH. I don't know how much pressure it would have at the outlet but it is one hell of a lot of air. It would certainly get my pigs excited.
 
Google v8 air compressor conversion. I believe that's going to be your cheapest, simplest option that doesn't require multiple units or oil flooded cooling and separators. Basically strip the heads off, and put plates on with check valves for each cylinder. Make the crankcase oil tight,but don't remove the lifters or it won't have oil pressure.
 
Google v8 air compressor conversion. I believe that's going to be your cheapest, simplest option that doesn't require multiple units or oil flooded cooling and separators. Basically strip the heads off, and put plates on with check valves for each cylinder. Make the crankcase oil tight,but don't remove the lifters or it won't have oil pressure.

I think I would try it stock, and keep the radiator.

Just tie the exhaust manifold to the tank.
 
I wondered about that. The problem is he is going into a rubber hose. With cam timing changes, I wonder how much pressure you could get from the exhaust of an engine.
 
I wondered about that. The problem is he is going into a rubber hose. With cam timing changes, I wonder how much pressure you could get from the exhaust of an engine.

Even without timing changes, the compression energy should be 90% returned to the crank on the downstroke (no fire).

As far as rubber hose, weld up some fittings to the manifold's flange,
and run some steel pipe to keep away from the heat (not that there is
allot)

EDIT:
If I was to do it again (and didn't have that surplus compressor I found)
I would try a detroit 2-stroke.
Advancing the cam on that would make more sense, as the exhaust valves
open on every up stroke (if you advance it)
 
Your problem is that at your requirement you are talking serious money......your 300cfm Sullair would run $50,000 exchange for an airend.........50psi is far too high for a lashup..........I dont know if you have found out......but even the bronze diaphragm in a Sullair governor is $300...about 2"dia............an engine conversion would likely need flat plate heads fabricated..........Le Roi used to do something like this with a V8 ....4cyl engine/4 cyl compressor.
 
Your problem is that at your requirement you are talking serious money......your 300cfm Sullair would run $50,000 exchange for an airend.........50psi is far too high for a lashup..........I dont know if you have found out......but even the bronze diaphragm in a Sullair governor is $300...about 2"dia............an engine conversion would likely need flat plate heads fabricated..........Le Roi used to do something like this with a V8 ....4cyl engine/4 cyl compressor.

Yup...what John said.

I happen to own a v-8 engine conversion compressor, it's a ford 302 (or 351 I
cant recall at the moment, I do have the book for it)
and 4 cylinders pump. IIRC a Grimmer Schmidt.

Puts out 150 cfm at 120 psi.

So if you took the whole engine and spun it with the PTO you'd get twice
the CFM.
 
Honestly its way less effort to just push the pigs through with water, you already have the pump to do that and it rinses everything at the same time. Simple fold out water tank you can raise the pump up and sit in are but a few hundred over here, most farms easily have the means to fill one too.
 








 
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