the unit I listed above is a vent unloader self contained, I have used one on a smaller compressor,
Compressor Components
more info
http://www.rossbrownsales.com.au/files/continuous_run_vent_unloaders.pdf
Load Genies & Unloader Valves
there are diffnret sizes depending on CFM requirments
a saftey valve will not close untill your considerable lower psi than what your wanting they may blow at say 125 or what ever they are rated for but my not reseal untill 40 psi, they will work the way you would want them to for that pourpose,
my compressor uses a a head unloader, the unloader works the valves in the compressor and so it does not pump,
I see the Load Genie is indeed designed to control pressure by exhaust flow, and your explanation of the relief valve limitation makes good sense. Thanks!
dynasim
Re: PTO driven air compressor
I have purchased the equipment to make a hydraulically driven compressor using the harbor freight 2 cylinder compressor, and a surplus center hydraulic motor.
I am a bit worried about the pressure cycling on the motor, but the power on a 10 gpm flow circuit works out just right. I want to use a pilot driven hydraulic diverter, but will have to see if I can find or make one. The goal is make a compressor that only needs a very small tank(I can adjust the tractor speed to get the compressor capacity I need).
The all in(with a pneumatic unloader) is about 500$ for a 20 cfm, 150 psig, compressor.
The hydraulic part of it should make it safer and easier to use.
Chris
That should be a nice setup. Are you planning to use two compressor units to get 20 cfm?
Groo
Re: PTO driven air compressor
While I like the simplicity of a direct drive, based on the low power requirements of the compressor compared tot eh tractor's PTO rating, having the tractor near idle and gearing up the compressor would made more sense. You could also incorporate an electronic clutch easier that way too.
I guess its just a matter of how much time do you want to put into it vs. how much will you use it.
I agree and if I wind up using it a lot, I will do exactly that.
zzvyb6
Re: PTO driven air compressor
A really good idea ! I like this approach because for me it would be for intermittent use only. My shop compressor can run the other stuff, ok.
I had been thinking about a mid-pto compressor, but then I got a rotary 540 air compressor made in Italy to use out in the field for tire service, etc.
So what do you need to complete the sandblaster system ? A blast cabinet (obviously), and a shop vac, but what else? Would you need a reservoir tank and pressure regulator, dryer, etc?
I'm all ears !
This will be for blasting outdoors with a pressurized blaster (also from HF
) although I do use a blaster cabinet (also from HF
) in the shop. Dust is managed with a 1 HP dust collector (also from HF
). I run the air through a copper coil inside an old fridge (freezer section) then a long section of copper pipe to cut down moisture as it helps keeping the sand dry (also important for painting).
One key often overlooked, is nozzle size. The newer deadman valve from HF is a big improvement with 4 nozzle sizes. With 10 cfm I can almost keep up to the 2nd smallest. Blasting speed with improve greatly with larger nozzle size allowed by more cfm.
I will put a reservoir tank on the pto unit since I have an extra, but this is optional as I'll be feeding it into the shop system which has a 60 gal tank. It will provide portability.
I got lucky and found one of the HF 2 cyl units, NIB on Craigslist last night so I'm going with that for now. I'm having a 4 1/2" circle laser cut from 1/4" plate steel and will weld on a pto adapter I found today. I'll drill a 7/8" hole in the end of the adapter for access to the flywheel bolt. 4 1/2" is the size of the flywheel hub. It will be drilled and bolted on (3 holes). I chose 4 1/2" to make centering easy, and laser cutting to minimize imbalance.
