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Air Distribution Systems

The distribution system is the piping or hose that is used to carry the air from the air compressor to the air tool. The pipe or hose size should be large enough to keep the pressure drop between the tank and point of use to a minimum.

The first step in designing a system layout is to determine if it will be a portable or a stationary system. A portable system allows flexibility in easily moving the system to different locations. This could be used around the shop, home, or to different job-sites. The disadvantage is that some efficiency must be sacrificed for portability. A properly designed stationary system is the best and most efficient set-up. The disadvantage is the loss of portability and higher up-front cost.

Regardless of the system you choose they should all included the following components: 

• Distribution system (piping, hoses).
• Filters.
• Regulators.
• Lubricators.
• Fittings.

Portable systems are relatively simple in terms of design and cost. Most often they involve a hose attached from the air compressor to the tool. Despite their simplicity, there can be several problems. First, long lengths of hose can become very heavy and cumbersome to handle. Second, filters, lubricators, and regulators should be installed close to the tool for best performance, which is sometimes difficult to do. Finally, too many fittings, couplers and small hose diameters are often used resulting in poor tool performance and productivity.

To maximize performance, keep the total length as short as possible, taking into account that extension cords are not recommended on air compressors. Also, use as few quick connects as convenience allows. If you do use more than one quick connection between the compressor and tools, install larger connects. If using multiple tools, run a larger main air line then distribute into shorter and smaller branches.

A stationary distribution system offers several advantages. A properly designed system can offer cleaner air of the appropriate volume and pressure translating to better tool performance and worker productivity. Outlets can be installed at the point of use, allowing the air to be conditioned properly for the application.

System design should start with a layout of the shop. Designate where and what tools will be used. Determine the placement of the main line. Try to keep the line as short as possible while providing access to where the tools are used. Try to keep in mind any future needs or alterations.

It is much easier to make changes down the road if they are planned for. Drop supply line at the point of use or regular intervals to minimize hose length. Size the line properly. Each supply line should be installed with a filter and regulator. Designate appropriate supply lines as clean air lines for use with paint guns, blow guns or tire chucks. On lines operating air tools install lubricators to extend tool life. See our Air Preparation article for specific set-ups.

Pipe materials, joints, fasteners, and adhesives must exceed the air compressors maximum pressure. Copper, galvanized or black pipe is preferred. Do not use PVC pipe for compressed air. Piping is divided into the main line and branches. The main line is used to carry air throughout the system. Branches are used to bring air to the point of use.

The main air line should not be smaller than the compressor outlet size. It should be sized by the continuous SCFM for all of the tools and the total length of the pipe. To figure the total length of pipe, start by making an accurate sketch of your shop and layout. Refer to the following table to determine the correct pipe I.D. Air branches are sized in similar fashion to the main air line. The exception is that rather than using the total system SCFM, size the branches by total consumption of the tools running off that branch.

 Air hose length should be kept to a minimum. Just as the piping was sized to the tools’ SCFM and distance, so should the hose. Typically only one tool is run off an air hose at a time. To size the air hose, Select the tools with the largest SCFM, determine the distance and refer to table the following table. If this is a portable system and the main hose supplies several tools, use the tool’s total SCFM to size the main line.

 Properly installed pipe minimizes the amount of moisture at the point of use. Piping should slope in the direction of the airflow (away from the air compressor) to an accessible moisture drain point. Outlets should be taken from the top of the main air line (tees facing up) to keep moisture out. A drain leg should extend below the outlet with a ball valve on the end. Moisture should be drained daily.

 Assemble and test for leaks one section at a time to avoid major disassembly later. Install pipe unions at regular intervals. This makes future repairs and modification easier. Always use thread sealant with PFTE on threads to eliminate air leaks. Do not over tighten tapered threads as this could cause the fitting to crack. Secure air lines to a solid surface using pipe clamps.

 Although they may seem minor, air leaks can be quite costly. An air leak will reduce the amount of air to the tool causing less worker productivity. Furthermore, an air leak will cause the compressor to work longe

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