air compressor basics

tractorman1234 · Sep 30, 2008

I have some general questions on air compressors. Several things I have ideas on but was not really sure.

I have upgraded the pump on my compressor and it puts out 13 CFM @ 90 PSI and has a max pressure of 135 PSI.

The pressure switch I have has a range of 30 PSI. I assume I should set it to go off at 135 PSI and on at 105 PSI?

With the above settings on the pressure switch what should I set the regulator at for maximum efficency? By that I mean when using certain tools they specify a pressure and I set it at that but when I am blowing things off or airing up tires where should I set it?

On one hand wide open at 135 makes sense but then something below 105 maybe 100 sounds good too because I should be able to maintain that pressure always as the pump will kick on when it gets to 105 and hopefully it will never dip below 100 thus I always have 100 psi?

kenmac · Sep 30, 2008

all depends on the tools that you are using ( cfm) I would set the pressure cut off switch at about 130 psi. Unless you have a high volume compressor pump ( again, depending on the cfm you are using , You most likely will not be able to mantain 100 psi after the pump comes on. If you stop using the tool ( say an air sander ) & let the compressor catch back up you you can maintain 100 or 135 in the tank. Tools aren't usually rated for a pressure. They are rated by cfm . I have a port b-4 the regulator for airing up tires & blowing things off. Another port at the regulator for air tools

ToadHill · Sep 30, 2008

You need to check on the air pressure that the tool you plan to use needs to operate. As for blowing things off I use about 40 lbs and for pumping things up I leave it at its normal setting and check the pressure with an air gage.

Bird · Sep 30, 2008

For painting (and perhaps spraying other liquids) a pressure regulator needs to be set for whatever is recommended by the sprayer for the material being sprayed; usually no more than 40 psi or less.

Nearly all air tools are rated at 90 psi. In other words, an impact wrench will produced the amount of torque the manual says it will produce if you have air pressure of 90 psi. The tool will work with less air pressure, but not have as much power. It will also work just fine with more air pressure and will have more than the rated power. Of course, you'll have a little more wear on the tool, you may even break it, and if the manufacturer knew you were running higher pressure, it might void the warranty. The fact of the matter is that many mechanics routinely run 175 psi and just figure the extra power is worth any repair costs.

Most air blow guns call for a maximum air pressure of 30-35 psi. The one I use most frequently has 30 psi maximum stamped right on the side of it. I'm sure most folks know that's to cover the manufacturer for liability in the event of an accident.

My current compressor kicks on at 125 psi and off at 155 psi. I certainl will not tell anyone to do something different from what the manufacturer says, but I leave my regulator wide open unless I'm spraying liquids.

All 3 of my air blow guns work very well at that pressure.

SPIKER · Sep 30, 2008

sounds like you are only using one tool at a time from a med sized compressor and don't have any shop system of air lines and sepperate hoses ect. if using one tool at a time most tools require as stated 90 psi at the tool inlet. if you have 100 feet of 3/8" hose then set the regulator on the compressor to 90 then the toll will have less pressure at the toll as it is running due to losses in the lines. it is better to run most tolls at or slightly above the rated pressure as VOLUME is needed to drive them (air sanders DA sanders & impacts all use HIGH volumes of air so any and all hose/line restrictions will cut down on volume the tool needs and will slow the performance.) Using a paint gun then you should have a HOSE REGULATOR attached at the gun to make sure you get exact requirements for what you are spraying., (I painted for years) using regulator on other tools usually is not needed but can be really handy when grinding using a die-grinder to set speed and power needed for each tool in each postion. anyhow have fun wear safety glasses as anything can happen.

Mark

schmism · Sep 30, 2008

my friend that runs an automotive shop runs a two stage compressor (175 psi tank pressure)

runs he regulates line pressure to about 150 psi and runs everything wide open. he has never had problems with air tools at that pressure.

the only time you dont want high pressure is when your painting.

sanders, paint guns, drills, grinders all take TONS of CFM...

zuiko · Oct 1, 2008

For blowing stuff off and inflating stuff I leave the regulator at 90, which is what I use for most tools (impact wrench, nail guns, etc). The only time I mess with the regulator is when I have to paint something... that needs a lower pressure.

Oh yea... I also upgraded to 1/2" hose over the more common 3/8" hose... still use the same size fittings (with adapters) though since I didn't want to have to change them all. It makes a big difference when it comes to stuff running stuff like the impact wrench. I get a lot more power with 1/2" hose than I did with 3/8" hose.

kenmac · Oct 2, 2008

The glass bead machine uses more CFM than any air tool I own. I ran a 1/2'' air line to supply it

Bird · Oct 2, 2008

kenmac said:
The glass bead machine uses more CFM than any air tool I own. I ran a 1/2'' air line to supply it

Yours may be bigger than the one I had, but I sure do miss it. When I was repairing/rebuilding air tools, that glass bead machine would clean out rust that I just couldn't get to any other way, but with my little machine, I actually just used a 10' quarter inch hose. The highest consumption (CFM) tools I worked on were the bigger sanders and angle grinders, and of course the 3/4" impacts.