Air Compressor Piping Rules Of Thumb .
After leaving the air compressor, air line pipe goes straight up the shop wall as high as possible. This helps minimize any water from leaving the compressor and traveling through the pipe. List of 1 items . Slope main lines at least four inches (10 cm) per 50 feet (12.7 m) of pipe away from air compressor so that condensate travels with the flow of air and away from the compressor. As warm air leaves the compressor, it cools and thereby condenses as it travels through the pipe. This water vapor, a problem in itself, can also cause scaling and rusting inside the piping. Install drop legs for condensate removal. . The first air drop should be at least 25 ft. (6.4 m) from the compressor although 50 feet (12.7 m) is optimum. This allows the compressed air to cool to room temperature so any condensation can occur before it gets into the water separator.
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Take-off comes from the top of the main air supply line at each air drop. This reduces the risk of water and other contaminants from traveling down the drop into the water separator.
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Use carbon steel pipe as discharge pipe material. Never use PVC or ABS. (PVC is easy to work with, but will not allow the hot air to cool quickly enough to condense the water in the compressed air. Also, in case of a compressor regulator failure, if the PSI inside the line were to go above the rated safety capacity, the plastic pipe won't just split, but will actually explode, producing razor-sharp projectiles which are sure to damage property and person.) Consider using Schedule 40 black iron, galvanized, copper, stainless steel, or anodized aluminum. Size the pipe for maximum CFM required. This will equal full load production plus future expansion plans. The size of the pipe is critical! Pipe diameter must be of sufficient size for the volume of air being passed as well as the length of pipe used. This will minimize pressure drop. Did you ever have only 60 or 70 pounds of pressure at the spray gun or other tool when your compressor should deliver 100 pounds? Using pipe that is too small in diameter can cause this pressure drop. For example, if an air compressor delivers 100 psi through a 100 ft. pipe, 1/2-inch in diameter, there's greater pressure drop than if a 3/4-inch diameter pipe were used. Use the chart below to match your compressor's size and capacity with the optimum pipe size.
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DISCHARGE PIPE SIZE CHART Compressor Size Compressor Capacity Main Air Line Min. Pipe Diameter 1½ & 2 HP 6 to 9 CFM Over 50 ft. ¾" 3 & 5 HP 12 to 20 CFM Up to 200 ft. ¾" Over 200 ft. 1" 5 to 10 HP 20 to 40 CFM Up to 100 ft. ¾" 100 to 200 ft. 1" Over 200 ft. 1¼" 10 to 15 HP 40 to 60 CFM Up to 100 ft. 1" 100 to 200 ft. 1¼" Over 200 ft. 1½" Courtesy of DeVilbiss, an Illinois Tool Works Company
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Use large enough pipe so as not to exceed 3 PSIG pressure loss through the entire line. (The target is a maximum 10% pressure drop through the entire system, i.e. from air compressor to farthest drop.)
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Discharge pipe is to be the same size as air compressor outlet. . A shut-off valve should be installed before each point-of-use filter. This allows air supply to be shut off for filter maintenance. . Install a pipe tee in the discharge pipe to blow to atmosphere if necessary for control and adjustment. This will also serve as a convenient connection for a rental compressor if required. . Install pressure gauges throughout the system for troubleshooting. Locations should include the receiver, headers, tools, production equipment and the end of plant piping system. . Use long radius elbows. Try to use flow resistant fittings and valves. Use ball or butterfly valves.
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Locate headers and sub-headers near air uses and manufacturing equipment. A loop system is ideal, providing two way flow distribution. . Do not connect multiple air users to the same drop. Use one drop for each air user. . Install an air receiver at intermittent high demand points such as occasional sandblasting, air motors, etc. Air receiver size should be one gallon of storage per 1 CFM of air compressor output as a minimum in order to permit the compressor controls to operate correctly. . Always consider leakage and future expansion in order to eliminate compressed air system obsolescence. A 10% per year growth rate is common. . Drain Valves: The daily draining of the system at each outlet disposes of the contaminants that build up in the air supply. Drain the compressor trap daily if equipped with a manual drain. Increase draining intervals appropriately during periods of heavy use. . Be sure to read and understand equipment instruction and installation manuals and discuss the layout and piping requirements before installation. . Proper maintenance of the air compressor can reduce airborne contaminants such as particles and oils, and reduce heat and operating cost. Check air filters, oil level and perform regular maintenance per operator's manual.