I have a brand new CH Model TL050299, 1/2" impact wrench running off a 20 gal, 3.5 HP Devilbliss compressor that delivers 6.8 scfm at 90 PSIG. The compressor regulator is set at 100 PSI, and I am running the tool at the end of a 25' 3/8" hose. Problem: it has NO power at all, regardless of the setting I use on the adjustable gage (1, 2, or 3). I can spin the socket under no load, but it is so weak I can stop the socket with my hand at any setting. Is this thing faulty, or is it cockpit error? (This is my first ever impact wrench, so I'm thinking the latter.....)

How would you know it isn't delivering the rated SCFM?
It is far from simple to measure this part of the specification.

While many manufacturers state the CFM in free air as a guide to choosing the right compressor and it is usually a theoretic calculated value using rpm and displacement.
It is interesting Kobalt has quoted an SCFM at 175 psi which is a very ambitious thing to do due to the many variable affecting compressor performance - temperature, humidity, supply current...

A 3.7 hp motor is similarly ambitious for a single phase supply (3-phase isn't stated). 2.5 hp is reckoned to be the maximum for a standard domestic supply and even then the high starting current can cause problems as well as when working hard a voltage drop on the supply will cause slow running. A short dedicated supply is preferable and for a 3 hp motor it is considered necessary.

I would say a short and really heavy dedicated supply is necessary for 3.7 hp and if any dimming or flickering of the lighting is taking place the motor will certainly be running at less than the rated speed and therefore a reduced air volume.

The two most important specs are CFM at 90 psi (that's how fast the compressor can compress more air when the tank starts to run low) and how big the tank is. Virtually any compressor that has a top pressure rating 20 psi higher than you need for your tool (which is usually about 90 psi) and that has a tank of a couple of gallons will work. But the smaller the tank, the shorter time you can operate the tool before the compressor has to kick in. And the lower the CFM at 90, the longer you will have to wait for the tank to come up to pressure again so you can operate the tool at full pressure. If this is for occasional use and you aren't in a hurry, you don't need much of a compressor at all. If you want to operate continuously, then you should get something with a CFM at 90 psi that is higher than your tool's CFM consumption. Keep in mind that impact wrenches don't operate continuously like paint sprayers do. Good luck. Vote if you found this helpful. Al K

Hi and welcome to FixYa, I am Kelly.

Air Tool consumptions are based on 15 seconds per minute (25%) of tool use.

Usage rates refer to the total time that air is flowing through the tool. If your applications result in more extensive usage, calculate air tool requirements as

follows.

(25%) 15 seconds = rated scfm x 1

(50%) 30 seconds = rated scfm x 2

(75%) 45 seconds = rated scfm x 3
(100%) 60 seconds = rated scfm x 4

Your impact wrench is rated a 8 CFM Cubic Feet Per Minute Usage

SCFM is Standard Cubic Feet per Minute (pre-compressed air volume)

I would be more concerned that the plumbing from the compressor tank could support the 8 CFM required by the 1/2" Impact. Remember the Air compressor will recover the pressure loss regardless of size. The only problem your going to have for "small jobs" is if you use too small of an air line to supply the impact wrench you are not going to get the full torque that it will produce to the drive head. In other words... a 1/4" supply line or 1/4 fittings anywhere in the system just isn't going to cut it even at 120 PSI. If you have the patience... a 5 gallon tank compressor that has the output volume required should be all that you need. I have been a mechanic over 4 decades and rarely have to use a 1/2 in impact for very long. Examples of 1/2" vs 3/8" useage. Wheel nuts, crankshaft pulley center bolt, some starters, steering, suspension and rear end parts. Other than that a 3/8" Impact works great.

One other thing you can do if you have an Air-Peen portable tank (with added fittings) is to add that in line with your output hose when your using the impact wrench so that you have longer use times.

I know this does not answer your what SCFM compressor is required question but it will resolve your needs. I just can't see telling someone that is a "small jobs" user to buy a larger compressor when really all they need is more volume for a brief period of time. The re-plumbed 1/2 inch output / in-line Air-Peen tank is a much cheaper and reasonable work around and you can disconnect that tank when your not using the impact wrench.
Lastly... if your inpact wrench has a SMALL male air fitting everything above will be a waste of time. You have to get that volume into the tool without restriction so that the rool will work properly for you.

Thanks for choosing FixYa.
Kelly

sounds like the pressure switch is faulty. not uncommon on compressors anymore.

You can get the manual for model 41214 from my dropbox area:

http://dl.dropbox.com/u/54567653/husky_aircompressor_model_41214.pdf

BTW, if you find this manual helpful consider installing dropbox using this link (full disclosure -- I do get about 0.2 GB freespace from dropbox if you install using this link):
http://db.tt/vQycqXIW

Thanks,K

Check to see if air is leaking past 'pressure relief' valve. It's probably leaking and that's where all the air is going.

If you need further help, I’m available over the phone at https://www.6ya.com/expert/craig_3fa289bf857b1a3c

check and see if the air is blowing through the pop off valve...little round plug with a ring hanging off of it. Also, check and see if the regulator has been turned up to a high pressure....air may be blowing through the regulator

You need to look at the tool cfm requirements because they are posted on the package or usually in the ads. Your compressor will run the sander, just how long at a time will depend upon your tool's cfm. Rick

One of the factors used to designate compressor power is motor horsepower. However, this isn't the best indicator. You really need to know the amount of air the compressor can deliver at a specific pressure. The rate at which a compressor can deliver a volume of air is noted in cubic feet per minute (cfm). Because atmospheric pressure plays a role in how fast air moves into the cylinder, cfm will vary with atmospheric pressure. It also varies with the temperature and humidity of the air. To set an even playing field, makers calculate standard cubic feet per minute (scfm) as cfm at sea level with 68 degrees F air at 36% relative humidity. Scfm ratings are given at a specific pressure–3.0 scfm at 90 psi, for example. If you reduce pressure, scfm goes up, and vice versa. You also may run across a rating called displacement cfm. This figure is the product of cylinder displacement and motor rpm. In comparison with scfm, it provides an index of compressor pump efficiency. The cfm and psi ratings are important because they indicate the tools that a particular compressor can drive. When choosing a compressor, make sure it can supply the amount of air and the pressure that your tools need.

One of the factors used to designate compressor power is motor horsepower. However, this isn't the best indicator. You really need to know the amount of air the compressor can deliver at a specific pressure. The rate at which a compressor can deliver a volume of air is noted in cubic feet per minute (cfm). Because atmospheric pressure plays a role in how fast air moves into the cylinder, cfm will vary with atmospheric pressure. It also varies with the temperature and humidity of the air. To set an even playing field, makers calculate standard cubic feet per minute (scfm) as cfm at sea level with 68 degrees F air at 36% relative humidity. Scfm ratings are given at a specific pressure–3.0 scfm at 90 psi, for example. If you reduce pressure, scfm goes up, and vice versa. You also may run across a rating called displacement cfm. This figure is the product of cylinder displacement and motor rpm. In comparison with scfm, it provides an index of compressor pump efficiency. The cfm and psi ratings are important because they indicate the tools that a particular compressor can drive. When choosing a compressor, make sure it can supply the amount of air and the pressure that your tools need.