Describe the critical differences between a confined space and a permit-required confined space, and explain how these distinctions impact entry procedures and hazard controls.

A confined space, generally, is defined as a space that is large enough and so configured that an employee can bodily enter and perform assigned work; has limited or restricted means for entry or exit; and is not designed for continuous employee occupancy. This definition focuses on the physical characteristics of the space – its size, accessibility, and intended use. Examples include tanks, silos, underground vaults, and certain large pipes or ducts. However, not all confined spaces present the same level of risk. A permit-required confined space (also sometimes called a "permit space") elevates the hazard profile. It shares the characteristics of a confined space, but critically, it also has one or more of the following: contains or has the potential to contain a hazardous atmosphere; contains a material that has the potential for engulfing an entrant; has an internal configuration that could trap or asphyxiate an entrant, such as converging walls or a floor that slopes downward; or contains any other recognized serious safety or health hazard. Examples include vessels containing residual chemicals or oxygen-deficient ....