Air impact tools psi and torque

[ajchien]

Hi guys,

Is there any calculation where I can say if I have a xxx psi on an air compressor for an impact tool, that it correlated with zzz amount of torque in ft-lbs?

 

[tomcat27]

nope. alot of it depends on the design of the air motor inside the air tool: design, tolerances, etc. And PSI alone will not tell the story - air flow (CFM) is just as important. Also, alot of the cheap China no-name brands dont come close to meeting their supposed specs. Also, you can make up for a lower horsepower air compressor by having a decent sized air tank. at least for impact wrenches. altho if you run a high-duty tool like a DA sander, you need alof of air!

 

[Steve S]

Usually the air tool has a psi and cfm listed in the Brochure or on the box. The bigger the compressor over needed power the better. Made in China impact or air ratchets [ Ingersol Rand have been really good to me!I am not really sure on the die grinders or cut off tools] are usually a letdown and not worth the money paid for them.

 

[oilboy123]

Using bigger air hose, fittings with bigger inside diameter makes a difference. There are too many variables to predict what will get.

 

[tom slick]

Air tools are generally designed to operate at 90 psi. You need more flow to get more power. If you are using an air ratchet and impact then you should be using a 3/8" air hose and matching fittings at a minimum. Most people forget about the air fittings.

 

[GeorgiaHybrid]

I prefer 3/8 hose with Milton type "V" fittings for my impacts that are 1/2" or less. As above, I run mine at 90 psi and depend on the airflow to get the performance instead of air pressure.

As a general rule, the name brand impacts will outrun the Chi-Com guns by a good percentage. People are still surprised when they come over and their guns will not loosen a crank bolt and mine (Snap-on and IR) will spin them off without any effort.

 

[benjamming]

For those that have their regulator set at 90 psi, you aren't getting 90 psi at the gun (more than likely). You may have to turn the regulator up to 120 to get 90 psi at the gun. You can always put a pressure gage at the end of the hose to see what you are really getting after the pressure losses.

 

[Steve S]

175 psi and 25cfm would make my I.R.231 able to break loose lugnuts on the semis at work. It too a bit of hammering but it was convenient. My Snapon was rebuilt 3 times and the I.R,231 never had a problem.

 

[oilboy123]

One thing I have noticed is the cheap air fittings seem to have small/inconsistent holes in the threaded fittings. The ones that go into the chuck.

 

[mechtech2]

Don't forget that lubing the air tools helps a lot with their output power.
It seals and reduces friction.

 

[mechanicx]

How many are running a drier on their compressor line? I have one but it doesn't seem to do much or ever catch any water in it.