I heard a story about connecting two small compressors together in order to increase PSI. Maybe it will be helpful in certain spraying applications off site. In theory, I guess this is like a two stage motor. In actual practice, however, does it work? If so, how do you do this?
From contributor R:
I have never heard of doing this. What are you trying to do? For spraying you need more volume, not pressure.
Connecting 2 compressors to the same tool using a tee of some sort is called in "parallel," not "series."
The only part I soft of disagree with is contributor P's concern about connecting 2 compressors in parallel. It may not be ideal, but I can't see any inherent hazard so long as the pumps are similar and set to similar pressures. It would be bad to tee together a big 2-stage industrial compressor with a little pancake unit, but 2 jobsite compressors together shouldn't be a problem.
1. Max volume of air supply.
2. Recovery time.
You need to eliminate the second pressure switch. Both compressors need to turn on at the same time, otherwise one will be doing most of the work. It should make little or no difference if you hook the compressors in line versus teed into the main line. Theoretically you could place the second compressor anywhere in the system and as long as the pumps start at the same time, it should be of little consequence. The working pressure of most compressors is about 125psi. I'm not sure why you would need higher.
You can replicate a part of this by just setting one compressor to kick in 2 or 3 pounds under the other. That way if the first one kicks in and the pressure continues to drop the second one kicks in. Set the new one to kick in first as you won't be able to alternate. T them together. There is no way to hook them in series.
Comment from contributor A:
Connecting the compressors together is ok if they both are about the same in output. I use a 4.5 gal 5.6 cfm Dewalt to a 8 gal 4.5 cfm harbor freight compressor. I do this for a number of reasons. First it increases the cfm and allows me to run my soda blaster (you should keep them both at same psi). This setup also lets you power each compressor with a different outlet which uses less power from each outlet so you have less of a chance to blow the fuses. The setup is also much quieter and less expensive to buy. The video below may be helpful.