What are the safety precautions that must be followed when working with compressed air?

The hazard of compressed air (and all other compressed gases) is often underappreciated. If compressed gas is uncontrollably released it can propel tanks weighing 200 pounds with enough energy to bend I-beams in commercial buildings and still fly for hundreds of yards. This concern decreases as the pressure decreases. So tanks of compressed gas must be well secured in storage and use, and their valves must be protected from damage

Other precautions include the following.

For Tanks: corrosion, dents/damage, valve operation, seals, welds, and especially the protective guard around the valve. Most types of compressed gas tanks require testing and re-certification regularly (annually, every 5 years, etc). For typical air compressors, follow the manufacturers instructions for draining the tank (to prevent internal corrosion) and drier use/inspection/replacement.

For lines/tools: High pressure lines must be secured with a tether at their connection points to prevent wild flailing lines. For all lines ensure regular lubrication of the connectors, and inspection of rubber lines for abrasion, chemical damage, cracking etc. The same for air tools. Do not modify any air tool. Even the holes on the side of a compressed air blower or nozzle are there for a reason. Air at over 20 or 30 psi can cut through skin. The holes make that impossible by ensuring that nozzle pressure cannot rise above a set point, even if the nozzle opening is blocked.