two green stripes painted around the top of thecylinder, while cylinders containing water-pumpedair have one green stripe. Oil-pumped air indicatesthat the air or nitrogen is compressed by anoil-lubricated compressor. Air or nitrogen com-pressed by a water-lubricated (or nonlubricated)compressor is referred to as water pumped.Oil-pumped nitrogen can be very dangerous incertain situations. For example, nitrogen iscommonly used to purge oxygen systems. Oxygenwill not burn, but it supports and acceleratescombustion and will cause oil to burn easily andwith great intensity.Therefore, oil-pumpednitrogen must never be used to purge oxygensystems. When the small amount of oil remainingin the nitrogen comes in contact with the oxygen,an explosion may result. In all situations, useonly the gas specified by the manufacturer orrecommended by the Navy. Nitrogen cylinders arepainted gray. One black stripe identifies cylindersfor oil-pumped nitrogen, and two black stripesidentify cylinders for water-pumped nitrogen. Inaddition to these color codes, the exact identi-fication of the contents is printed in two locationsdiametrically opposite one another along thelongitudinal axis of the cylinder. For compressedair and nitrogen cylinders, the lettering is white.POTENTIAL HAZARDSAll compressed gases are hazardous. Com-pressed air and nitrogen are neither poisonous norflammable, but should not be handled carelessly.Some pneumatic systems operate at pressuresexceeding 3000 psi. Lines and fittings haveexploded, injuring personnel and property.Literally thousands of careless workers haveblown dust or harmful particles into their eyes bythe careless handling of compressed air outlets.Nitrogen gas will not support life, and whenit is released in a confined space, it will causeasphyxia (the loss of consciousness as a result oftoo little oxygen and too much carbon dioxide inthe blood). Although compressed air and nitrogenseem so safe in comparison with other gases, donot let overconfidence lead to personal injury.SAFETY PRECAUTIONSTo minimize personal injury and equipmentdamage when using compressed gases, observe allpractical operating safety precautions, includingthe following:1. Do not use compressed air to clean partsof your body or clothing, or to perform generalspace cleanup in lieu of vacuuming or sweeping.2. Never attempt to stop or repair a leak whilethe leaking portion is still under pressure. Alwaysisolate, repressurize and danger tag out theportion of the system to be repaired. For pressuresof 1000 psi or greater, double valve protection isrequired to prevent injury if one of the valvesshould fail.3. Avoid the application of heat to the airpiping system or components, and avoid strikinga sharp or heavy blow on any pressurized part ofthe piping system.4. Avoid rapid operation of manual valves.The heat of compression caused by a sudden high--pressure flow into an empty line or vessel cancause an explosion if oil is present. Valves shouldbe slowly cracked open until airflow is noted andshould be kept in this position until pressures onboth sides of the valve have equalized. The rateof pressure rise should be kept under 200 psiper second, if possible. Valves may then be openedfully.5. Do not discharge large quantities ofnitrogen into closed compartments unlessadequate ventilation is provided.6. Do not subject compressed gas cylindersto temperatures greater than 130°F.Remember, any pressurized system can behazardous to your health if it is not maintainedand operated carefully and safely.11-9
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