Which of the following is NOT one of the criteria for classifying a permit-required confined space?

The criteria for classifying a permit-required confined space are established to ensure the safety of workers who must enter such spaces. One of the key characteristics of a permit-required confined space is that it typically poses specific hazards to entrants.

An open entry without restrictions does not meet the definitions or regulations for a confined space requiring a permit. Instead, a confined space is defined by its limited means of entry and exit. The purpose of requiring a permit is to ensure that adequate safety measures are in place to protect workers from potential hazards such as toxic atmospheres, engulfment risks, or physical structures that may cause entrapment.

In contrast, the other criteria relate directly to potential dangers present in the space. These include hazardous atmospheres that may be present or develop, material that could engulf a worker (such as liquids or loose solids), and structural characteristics that could lead to entrapment, such as inwardly converging walls. Each of these factors necessitates a permit system to ensure that hazard assessments and necessary safety measures are implemented before entry.