Is a big air compressor tank really needed?

[md21722]

If you are running high volume air tools such that your air compressor can barely keep up, but does, does it really matter if you have big a 60, 80, 120 gallon air tank? Asked another way, most 10-16 com air compressors are stationary and come with a 60 gallon tank but I did find a portable 3HP 10.3 cfm at Grainger that comes with a small 20 gallon tank. If you are going to use 9-10 cfm for minutes at a time, then does it matter if the tank is 20 or 60 gallon? I would rather have the more compact compressor to save space and get portability.

I have an 1/2" drive air drill and even plumbing together a 7.1 and 6.4 cfm compressor, together, they don't keep up. I don't think they are that far off, though. I am guessing if I replaced the 6.4 cfm with a 10.3, for 17.4 total, that I would be OK.

 

[crimsondragon]

Be careful with HP ratings. Unless it's 220v and above, anything above 2hp for a 110v is a gimmick. A bigger tank will only provide slightly more air time. I'd personally rather have a higher scfm rated compressor than a larger tank. Unfortunately, lack of 220v limits me so I have to get the big tank and let the compressor fill it slowly and then use it.

 

[old_man]

Air drills are notoriously inefficient and I never use one. DA sanders are also air hogs, but they are well worth the effort.

SCFM is what really counts, but a big tank really helps.

 

[ehall]

big tank that isn't needed still has to be filled and will overrun a pump with a low duty cycle

 

[md21722]

The air drill is listed as 4.5 CFM (32 SCFM). I am finding it hard to believe that it would draw a full 32.

The 3HP 10.3 cfm is a 220V unit. CH also makes one with a 26 gallon horizontal tank. If you have a 110V 20A circuit you could convert it to 220V depending on what else is going on with that circuit.

Another question, how does one effectively drain a horizontal tank? I prefer vertical with a drain opening in the middle. Some of the new ones are putting it on the side presumably because people complained the ones in the center were hard to get to???

 

[old_man]

The 3HP 10.3 cfm is a 220V unit.

I don't believe their claims. I run a 5hp220v that is only rated around 11cfm.

 

[md21722]

Is that a 5HP "peak" rating by chance where the motor is about 3.2HP? For the last 15 years or so that I've been paying attention, 3.2-3.7 HP compressors are generally rated 10.3 CFM @ 90 psi. Today most 5HP units are 15.8-18 CFM @ 90 psi.

 

[md21722]

Revisiting this thread. I've found that having a bigger tank keeps temperatures lower and that in turn keeps water from getting past my water separator. My 30 gallon compressor tank will get to 100F after a while, whereas the 60 gallon compressor tank won't get past 80. If using a smaller tank you'd probably need some sort of after cooler to achieve the same result.