The following is an excerpt from the Complete Guide to Laboratory Safety, Third Edition, by Terry Jo Gile. To purchase this book, click here. 
George was a technologist who worked with liquid nitrogen. He was in the habit of taking shortcuts when he worked, and today was no exception. After all, he’d been a lab employee for more than 30 years and knew his way around the policies and procedures. When he noticed that the pressure- relief valve on a compressed gas cylinder had ruptured the burst disc, he solved the problem with a couple of brass plugs and went on a lunch break. When he returned, George discovered that the cylinder had exploded and shot across the room, lodging itself in a brick wall.
Lessons learned from this experience:
- An exploding cylinder can have the same destructive effect as a bomb, potentially injuring those in the vicinity
- Any refill, repair, modification, removal of valves or pressure-relief devices, or other container modifications must be done only by a qualified technician, under the right conditions, and by a representative of the manufacturer of the gas cylinder
- As a lab safety manager, you could place George on a corrective action matrix for endangering the safety of himself and his coworkers
Compressed gases are hazardous due to high pressure and the nature of gas. Pressure creates the possibility of explosion, either of the container itself or by escaping gas. Different gases present different chemical hazards, potentially including fire, toxicity, corrosion, or asphyxiation by air displacement. Only a few types of gases are used in clinical laboratories, but a potential hazard is present even with just one cylinder.