Tag-Team Compressors

Is there any point in hooking two cheap compressors to a big air tank, rather than buy a heavy-duty compressor? March 26, 2007

I have a cheapo Chinese 21 gallon compressor that is barely adequate for my HVLP spraying needs, and absolutely useless for air sanders. I'd like to start using air sanders, but don't want to spend $500 - $1,500 on a big 80 gallon industrial compressor just yet. What about buying another cheap 21 gallon unit and connecting the two tanks together? That would give me an effective capacity of 42 gallons - but would the cfm stay the same, or increase enough to use air sanders? At $150 each, you can almost afford to burn up 4 or more Chinese cheapo compressors before paying for one really nice compressor... The one I have has been going for two years now with no problem (but I don't use it every day). Am I crazy to even consider this?

By the way, this cheap compressor is rated 3HP, with 3.5 cfm @ 90psi and 8.8 cfm @ 40psi.

Forum Responses
(Finishing Forum)
From contributor R:
Air sanders move right along at roughly 12,000 RPM. You will probably get less than one full minute of continuous use before the motor kicks in. Now, while the motor works its ass off trying to replenish the air that you have just used for a whole 45 seconds, what will you do? If you keep sanding, you most certainly will burn up the motor. If you stop sanding and allow the pressure to be built back up... 45 seconds later the motor will kick back in, and you will be back to square one. Either way you face a no-win situation with an air sander and Siamese compressors. Save up for a good two stage unit with plenty of power or better yet, look into a rotary vane compressor.

From contributor D:
Take it from a guy from the auto body world the air compressor is the heart of your shop! Don't try to save money here.

From contributor G:
It is quite common to connect two compressors in some applications. There is a control system that starts one compressor when your pressure drops to a preset level, then if your pressure drops another 5 pounds or so, it starts the other compressor. This controller alternates the two compressors when starting to share the load. This is more economical than starting a 10 horse compressor every time. You could simulate part of this by interconnecting your compressors and setting one pressure switch slightly lower than the other. Your CFM would be the combination of the two, so if this is enough to run the tools you need, then it should work and have the benefit of firing only one compressor when that's all you need.