help with setting up compressor

[estgranite2009]

hey guys can someone suggest how big of compressor tank, hp,needed to run a shop with 3 full time polisher? Thanks`

[CustomMarbleGranite]

I used a 7.5 hp for a few years but ran a lot . I now have a 15 hp witha 80 gallon storage tank and seems to hold up well. The 15 hp has a 120 gallon tank. Also if you haven't set up you airlines yet I would recommend doing a closed loop system so that all you drops have the same air pressure.

[estgranite2009]

thanks for the reply. any suggest on brand? with dryer or no dryer?

[VThartzog]

Pretty sure a dryer will ensure longer life of the polishers or anything else hooked up to it. I've used ingersoll and sullair. No problems with either

[jbergman]

What type of polishers? Any idea about cfm needed?

John Bergman

Bergman-Blair Machine Corp
Prescott, AZ
928-443-1100
516-381-6774 Cell

[william w]

get a dryer, it helps alot on making your polishers last longer.

[estgranite2009]

if i wants to run 3-4 polisher of 15cfm and 87 psi each machine. how big of hp and tank i would need? thanks

[Mark Meriaux]

The tank size won't make any difference in the flow rate (CFM). The tank acts like a buffer to help maintain a constant pressure by increasing the overall system volume. I.e. without a tank, when you turn on the 3rd polisher' the other two would instantly slow down due to the drop in system pressure, and all three polishers will equalize at the capacity of the compressor when it's maxed out and may not be optimal for productivity. A larger tank might allow you to run a 4th polisher for short periods (1-2 minutes) without slowing the other polishers that are running continuously.

Typical polishers use around 15cfm (roughly equal to 5hp) each. Running three polishers continuously will require a 15hp (minimum) compressor. At 15hp (and smaller), reciprocating piston compressors are much more affordable, but they are not designed to run continuously for extended periods of time and will wear out. You can run multiple reciprocating compressors together, but I would step the pressure switches slightly so that each compressor kicks in at a certain "stage" a with the understanding that your Stage 1 compressor will be the first one to need rebuilding or replacement.

Once you reach the 15hp threshold, it is worth considering a screw type compressor. They are more expensive, but are rated for long-term continuous duty and are extremely durable. You can also get these units with variable frequency drives (changes the speed of the motor depending on the load) to help with energy use on large hp motors.

Up to 15hp, a 120-150 gallon and is what I recall as a "common" size that is packaged with the compressors. If you go with multiple smaller recips, they typically come with 60-80gal tanks. Multiple tanks work the same as one large tank, except in systems with extremely long runs or possibly undersized piping (that would choke the air flow).

A dryer in the system will help remove moisture in the air lines. Moisture will cause premature wear in the air tools (polishers).

[Justzack]

Definitly loop the system and even with a dryer put in dirt and moisture traps at each drop. Ensure that your piping is large enough to carry the volume of air. also if you are looking to run 3 polishers, I would plan on more than 15 hp as 2 polishers and a blow gun will be over the air that you are making. Plus always buy bigger because who knows what the future will bring.

[Scruffy]

Pre packaged screw compressors/tank/dryers are not a bad choice and very easy to install. Just remember that they usually all have a WET TANK. The compressed air goes into the tank first and cools, loosing a lot of its water. It goes through the dryer before leaving the unit and into your piping. Both the tank and drier will drain water. Very good idea to have a dry tank after the unit.

[estgranite2009]

Thanks for all the help guys. Now last question I have is where do you guys buy your compressor from? Any suggestion on website or Grainger? Thanks

[coolhandchris]

I just bought a 20hp vfd(dimmer switch-style, uses less electricity based on demand) screw with a dryer and a 120 gallon tank. It was around 12k.

[barbianj]

What size airline is good to use? I see that Rapidair has a 3/4" flex tube system. Is that a good choice?

[Terry Roberts]

If you wouldn't mind, please send send me a PM on what the cost is on your new air system

[Ken Lago]

I started out with 3/4" copper pipe, when I upgraded to 1" aluminum pipe it drastically improved performance.

[CustomMarbleGranite]

I ran 2" for my loop and 1" for my drops. I also put a pressure regulator on each drop.
Works really well.

[Mark Meriaux]

First shop I had individual regulators at each polishing station. I had problems with employees deciding they wanted the polishers to run faster and would raise the pressure higher than recommended to the tools. Sure the tools ran faster, but they also wore out and broke more often.

My last shop setup, I had a large storage tank and held the reserve air at ~140 psi. Then I had a large regulator going out to the shop that I set and locked at about 95psi. Most tooling is designed to work at 90psi. Tools did not fail as often with this setup.