An air manifold is a large-diameter pipe thattransports compressed air from one or morecompressors over considerable distances withoutfriction line loss. In construction work, air manifoldsare usually constructed of 6-inch-diameter pipe withcheck valves. A pipe of this size can carry 1,200 cfm ofair (output from two 600-cfm air compressors) at 100psi with less than 0.035-pound pressure loss per 100linear feet. One or more compressors pump air into themanifold and then “pressurize” it at 100 psi. Air maythen be used at any point along the manifold by installingoutlet valves and connecting airlines to pneumatic tools.CAUTIONDifferent types of compressors should notbe used on the same manifold. The differencein pressure control systems of a rotary, areciprocating, and a screw compressor couldcause one compressor to be overloaded, whilethe other is idled.Any drop in pressure between the compressor andthe point of use is a permanent loss. Because of this, theair distribution system is an important element of thecompressed air system. When planning the air system,you should observe the following steps:. Pipe size should be large enough to ensure thepressure drop between the compressor and the point ofuse does not exceed 10 percent.. Extremely long distribution lines should have airreceivers near the far ends or at points of occasionalheavy use. Many peak demands for compressed air areonly for an instant, and storage capacity near such pointsprevents an excessive drop in line pressure.. Each header or main should be provided withoutlets as close as possible to the point of use to permitshorter hose lengths and to avoid large pressure dropsthrough the hose. Outlets should always be located atthe top of the pipeline to prevent carry-over ofcondensed moisture to the tool. Condensate drainsshould be positioned correctly along the header or mainline.SAFETYGeneral safety precautions for air compressors areas follows:. Be sure the intake air is cool and free fromflammable gases or vapors.l Do NOT permit flammable materials to touch theair discharge pipe.l Never operate a compressor that has faultygauges.l Never kink a hose to stop the air flow, and keepthe hose clamps on tight.. Before starting an air compressor, check thesafety valves, pressure valves, and regulators to see thatthey are working properly.. Do NOT leave the compressor after starting itunless you are sure the control, unloading, andgoverning devices are working properly.. Do NOT run an air compressor faster than thespeed recommended by the manufacture.l Use only the grade and amount of oil recom-mended by the manufacturer. Use only high flash pointoils to lubricate the air cylinders of air compressors.. Keep compressors, tanks, and accompanyingpiping clean to guard against oil vapor explosion. Cleanintake air filters regularly.l Use only soapy water or a suitable nontoxic,nonflammable solution for cleaning compressor intakefilters, cylinders, or air passages. Never use benzene,kerosene, or other light oils to clean these parts. Theseoils vaporize easily and form a mixture that is highlyexplosive under compression.. Secure the engine before adjusting and repairingan air compressor.. Before working on or removing any part of acompressor, make certain that the compressor is securedand cannot be started automatically or accidentally andthat the air pressure in the compressor is relievedcompletely. Also, ensure that all valves between thecompressor and receivers are closed.l Be careful with compressed air. At close range,it can put out eyes, burst eardrums, and cause seriousskin burns.Always wear impact goggles or safetyglasses and dual-hearing protection when usingcompressed air. NEVER use compressed air to blowdust off clothing, skin, or hair.l When transporting a compressor or any othertowed unit, ensure the pulling unit meets specifications.This includes drawbar horsepower and height of towingpintle (not too high or low because it can damage the14-9
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