What's more important, CFM or the size of the tank?

For instance, Harbor Freight has a 30 gallon unit that puts out 14.5 CFM @ 90 psi and 16 CFM @ 40 psi. Seems to me that the tank size is of little consequence if the pump can't produce enough air to replace what's being drawn from the tank.

Isn't it true that a larger tank just extends the amount of time the compressor is idle when you start draining the tank by using a tool. And if you're using a 9 CFM tool and you have a 7 CFM compressor the compressor will never catch up until you stop working.

But conversely, a 9 CFM will maintain operating pressure regardless of how long a 7 CFM tool is running.

Or am I missing something?

Woody
Your Brother in Bolthood

My 1951 half-ton 'Ol Red

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