I just picked an old air compressor,that I can tell has been pieced together.The tank is only 20gal, the pump is 2 cylinder,and the motor is a 2hp 3450rpm belt driven set up for 120v with the option of running 220v.Is there any way to calculate the CFM? Also I don't have 220v inthe garage,but I do have another el cheapo 120v campbell hausfield 30gal upright.Is there any reasonable way to connect the two compressors? Or is 220v the only answer? Thanks in advance.
The big one is all the compressor you'll need. Trade the small one to a compressorless buddy who will forever be in your debt.
If You Know The Model And Serial # And What Make The Pump Is I Can Probably Get The Info You Need If You Are Still Interested.switching Voltages Wont Get You Any More Cfm The Pump Will Only Make What It Is Going To Make,as Long As Your Pullys Are Correct.ptutting The Two Together In Your Garage(i Am Assuming)will Probably Blow A Breaker If Anything..........unless You Have Three Dudes Working At The Same Time You Only Need About 18-20 Cfm And About 90 Pounds Of Pressure.the Higher You Go On The Pressure(above 90)the Cfm Starts To Go Down.the Pumps Are Generally Rated From The Factory At 90 Witch Is What 90 Percent Of Any Air Tool Will Need.
so i think what your asking is if you can run both comps off the same presure switch, and the answer is yes, but one of the motors would have to have a delay so you dont blow the breaker. to set up a delay might cost you more then buying a nice new 5 horse 18 cfm comp.
Usually, the bigger the tankm the better the CFM and the less times the motor will kick on. I have a 120 gal tank, old 3 cylinder Ingersoll Rand. But you want at least a 60 gal tank if you are going to run an air sander (they use the most CFM)
Depending on what's running on the circuits, you (likely) won't blow a breaker/fuse if you connect them to 2 different circuits. It sounds like you'd need at least a 20 amp 110 V circuit for your 2 hp and use as short a 12 gauge wire as you can. CFM, horsepower and tank size are not related. If you have a 60 gallon tank and a wimpy compressor you're defeating your purpose. Once the tank runs out of air you'll have to wait forever to pump up the tank again. The compressor (not horsepower) gives you CFM, the tank is only stored volume. 220 is a better way to go if you can. Is there a clothes dryer near by?
What are you going to be doing that a 2 cylinder compressor isn't going to handle? If it's wired for 120 right now, why can't you just plug it in? As mentioned, you should look into a larger tank. But if a guy really wanted to rig it, you could sissy the tanks up and unhook the smaller compressor. It's really overkill to run em both. Another idea would be to hard pipe your garage, and put another tank somewhere in the system.
The tank is just a wide spot in the air line. No different than running 1000' of air hose. It's all about the pump. If you run a D.A. sander for 15 seconds and the tank pressure will drop enough to kick on the pump, then all that matters is what the pump will do. Lowes, Home Depot, and Sears have made alot of money selling cheap imported pumps bolted to big air tanks. They get big cfm numbers by spinning their pumps at high rpm. Good pumps don't have to turn that fast to pump air. I still see 50 year old cast iron Ingersol-Rand, Champion, Quincy, and Kelloggs thumping away.
well if I try to run a cutoff wheel it plays catch-up and loses with both of my compressors. My upright is only rated at 6cfm at 90psi, and like I said earlier I don't know what the other one is.Running the sissy tank sounds like it may be a good idea.
Not really. You get pressure drop with line, a tank acts as reserve power to give the compressor a chance to cycle. But totally agree if the load exceeds the compressor, no amount of tank will save you. I find it suprising a 2 cylinder compressor, even a small one, can't keep up with a cutoff wheel.
Some of the cheap (HF) air tools are mis-rated on air consumption. I tried out a couple of them, boxed them back up and headed to HF to return them. Two of the most overlooked areas are buying good not cheap air tools and buying an air compressor rated for the work load you anticipate. It cost about $400 more to get my industrial rated compressor than the ones sold at Lowes, etc. I have an Industrial Air 2 stage with an 80 gallon tank and it will catch up and shut off when I am using my Cyclone blast cabinet. When looking at compressor motors make sure the motor is work load rated. A lot of the cheap compressors have motors that are rated under no load conditions which is why you see the rating on some compressors that state "peak" horsepower. Run from a "peak" horsepower rating! Also better compressors intended for real shop use will usually have magnetic starters rather than capacitor start. Buy a good compressor the first time and you will have it for years and years and ...
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