I Got A Compressor Question, Please

[Ken Massingale]

I'm needeing a bigger compressor and that 30% HF coupon is hollering at me.
HF has a 21 gallon 3 hp with this rating:
4.0 cfm @115 psi
4.4 cfm @ 90 psi

Will this be sufficient for spraying, framing nailers, etc.?
TIA

[cabinetman]

In general terms, the tool you use has a recommended air pressure (PSI) to work properly and a demand (CFM) it uses. On most compressors, when the tank empties to a certain pressure, the compressor kicks on and produces its output to fill the tank. That output is constant. The tool you are using will consume less air from the tank when it runs at less air pressure.

For a small output compressor, when the tank gets to the recycle stage, and the tool you're using is using the demand that is equal to the compressor output, the compressor will stay running to meet the demand. If the tool has a demand greater than the compressor, it will quickly start slowing down the compressors' output ability.

For example, if an air tool is efficient at 90 PSI and needs 10 CFM, and the compressor has a total output of 6.5 CFM, the compressor won't be able to sustain the tool.

Your decision to decide on what to get should be based on the use you think you'll need. Spending the money once might save you in the long run.

[Stytooner]

I have that compressor as a backup now. I don't think it would keep up with a sprayer, although its a nice little compressor. It would not keep up with my sand blaster. I had bought a 3 hp motor from HF for my big compressor and bought the extended warranty. I knew it wouldn't last, but I needed something then. It went out after 9 months and now evidently HF no longer sells the compressor type motors large enough for my big tank. They applied the motor money to this compressor and I wound up with a backup for $80. I have since ordered and installed a good motor for my big compressor. I ordered a 5HP WEG motor from Surplus Center. Now I'm all set for blowing a lot of hot air.

[Lonnie in Orlando]

Ken:

I am happy with my 21-gal HF #47065 115volt compressor. Tank size is probably as important as SCFM ratings. It puffs a lot longer than my previous 8-gal compressor. Very obvious when using a blow gun ... much longer between cycles.

The specs on mine are different from those that you noted. Mine states 3.5@90# and 8.8@40#. No rating for 115#. Don't know how accurate HF's specs are.


http://www.harborfreightusa.com/usa/...o?itemid=47065

I have only used it a few times with my 10-g and 15-g nailers, but it did not recycle too often. It will shoot brads all day long.

I used it once with my HF 90977 HVLP gun to spray some Adirondack chairs w/oil based paint. I didn't push it. It recycled fairly often. I stopped a few times to let it completely recharge the tank, but it never ran out of air. I wouldn't want to paint a car with this compressor.

The specs on the 90977 gun state that it requires less air than other HF HVLP guns.


http://www.harborfreight.com/cpi/cta...emnumber=90977

- Lonnie

[Ken Massingale]

Thanks guys.
I 'think' I got 2 No's and a Maybe! ;-D

[maxparot]

I had 1 of those compressors at work. Besides being extremely loud I say it's a bit weak for a 2hp let alone for 3hp. For a frame nailer it would do the job but for spraying I'd go for a better unit. HF stocks some better units with regular prices of about $399 use the coupon and get something worthy.

[Andrew Benedetto]

HF in their larger general line seem good. I do not want any A/C that stops @ 115psi. With line drop , even 125-off/ 90 on is a problem. I have my Hitachi twin tank set at 135/100 and that would be 90psi at the framegun @ 50' of 1/2" hose. You have to see what is produced at the tool. I have a 2 stage 80gal that I set at 145psi @ the regulator and w. my impact running it is 100psi/50'/1/2" hose.
As Max said ,spraying continuous use, not enough, and you have to look at the duty rating. My 5.5hp/24A/240v/ 2stage is rated at 50%/hr on/off. That is where the 80gal helps due to the storage and 180psi in the tank. I would say to spray large objects I would not want anything else.
Spend as much as you can b/c if you buy big then you will never need another A/C.