Tips for supplying shop air

Author Cutting Tool Engineering
March 01, 2011 - 11:15am

Many CNC machines require air at a certain pressure and volume to run. If the air supply goes down, it can impact the entire operation. Thus the shop air supply is a critical path in the modern metalworking shop, and a high-quality, properly maintained system is crucial. Following are some air supply considerations and tips. 

Shop size and machinery dictate compressor size. Be sure to engineer in-room and branching possibilities for future expansion when choosing a piping system, compressor and storage tank.

Consider multiple, strategically located air tanks instead of one large storage tank. Often it’s easier to find precious floor space for smaller tanks.


Courtesy of All images: T. Lipton

Hose reels help store air lines.

The distribution network should be steel or copper pipe. PVC works and is safe under most settings, but has a cheap, rookie look. OSHA requires that anything below 8 ' off the floor must be metal, so you might as well make the whole network metal. Copper gets my nod of approval for its corrosion resistance and low leak potential.

When in doubt, place a valve. Each drop and dedicated air line to a machine should have a valve. You should have the ability to isolate areas for maintenance, repair or expansion without having to shut down the entire air distribution system.

Ch04.Fig008.Lipton.Drain Cock2.tif

A simple drain cock in the bottom of every drop allows shop personnel to bleed accumulated water. 

Dedicated air nozzles on machines should be plumbed to the hoses without quick disconnects. This prevents the inevitable unwanted removal and wandering of the air nozzle and the time wasted hunting one down.

For whatever reason, some drops seem to collect more water than others. It’s great if you have a chiller dryer on the compressor, but few air systems are completely free of water. Therefore, provide a way to remove the water. Simple drain cocks in the bottom of every drop allow shop personnel to easily bleed accumulated water.

Assign the duty of draining the compressor to an apprentice on a regular basis, typically three times a month. If the compressor is used heavily, invest in an automatic drain.

The air supply to the air nozzle should be regulated to a lower pressure than the main shop air. This reduces raw noise and is safer against bare skin. Over time, this type of noise on unprotected ears will cause hearing damage.

The hose for a dedicated nozzle should be optimized for length. A long coil of unused hose lying on the floor collects chips, coolant residue and junk; it’s hard to clean around and can snare legs. For air blower nozzles, a small ID makes for a lighter, more flexible hose while maintaining flow.

Air-tool supply lines are sized for each tool. Use your largest air hog to determine hose ID. If you’re doing delicate work with small tools, you can make a short whip of hose up to 6 ' long that has a smaller ID and connects to the main hose. This keeps the large main supply hose from dragging your arm down all day. On a couple of my tools, I have plumbed the whip into the tool body to eliminate the bulky connector or swivel joint.

Hose reels are great for neat, clean storage of air lines. Put two at opposite ends of the shop and have them slightly overlap in length when the hoses are fully extended. Don’t forget to put a universal female coupler on the end. Also, be sure to include a valve right before the hose reel so you can service the reel.

Don’t let the hose slide through your bare fingers when retracting the hose reel. Razor sharp chips get stuck in the hose surface and will slice your hand. Instead, keep your hand on the quick disconnect at the end. Pain awaits the daydreamer or unwary with a bad gashing.

Don’t drive forklifts or other heavy, wheeled machined over light-duty air lines. Otherwise, you will considerably shorten line life by driving chips and metal scrap into the surface. I got yelled at for doing this many times as a teenager, so now I get to pass it on.

Air-tool oil should be readily available near air supply points. This accessible location encourages the lubrication of expensive pneumatic tools.

Provide simple, professional-looking hooks for storing air hose extensions. Nails and spikes are for carpenters and other woodchucks. A similar hook works well for getting extension cords off the floor. Your hoses and cords will thank you with extended life.

Use universal female quick disconnects. These fit several of the most common types of male plugs encountered in air systems. They save time hunting for the correct fittings or adapters. It seems like every shop independently decided to use a fitting diameter opposed to every other shop’s fitting. I have a little box in my toolbox with every adapter under the sun to prove this. CTE

TomLipton.tif About the Author: Tom Lipton is a career metalworker who has worked at various job shops that produce parts for the consumer product development, medical services and custom machinery design industries. He has received six U.S. patents and lives in Alamo, Calif. Lipton’s column is adapted from information in his book “Metalworking Sink or Swim: Tips and Tricks for Machinists, Welders, and Fabricators,” published by Industrial Press Inc., New York. The publisher can be reached by calling (888) 528-7852 or visiting By indicating the code CTE-2011 when ordering, CTE readers will receive a 20 percent discount off the book’s list price of $44.95.

Related Glossary Terms

  • computer numerical control ( CNC)

    computer numerical control ( CNC)

    Microprocessor-based controller dedicated to a machine tool that permits the creation or modification of parts. Programmed numerical control activates the machine’s servos and spindle drives and controls the various machining operations. See DNC, direct numerical control; NC, numerical control.

  • coolant


    Fluid that reduces temperature buildup at the tool/workpiece interface during machining. Normally takes the form of a liquid such as soluble or chemical mixtures (semisynthetic, synthetic) but can be pressurized air or other gas. Because of water’s ability to absorb great quantities of heat, it is widely used as a coolant and vehicle for various cutting compounds, with the water-to-compound ratio varying with the machining task. See cutting fluid; semisynthetic cutting fluid; soluble-oil cutting fluid; synthetic cutting fluid.

  • corrosion resistance

    corrosion resistance

    Ability of an alloy or material to withstand rust and corrosion. These are properties fostered by nickel and chromium in alloys such as stainless steel.

  • inner diameter ( ID)

    inner diameter ( ID)

    Dimension that defines the inside diameter of a cavity or hole. See OD, outer diameter.

  • metalworking


    Any manufacturing process in which metal is processed or machined such that the workpiece is given a new shape. Broadly defined, the term includes processes such as design and layout, heat-treating, material handling and inspection.

  • shop air

    shop air

    Pressurized air system that cools the workpiece and tool when machining dry. Also refers to central pneumatic system.