Manholes, sewers, boilers, silos, vessels, vats, pipelines, tunnels, storage tanks, ship compartments and underground vaults can be classified as confined spaces.
Some May Not Be So Easy To Recognize.
Open-topped water and degreaser tanks, open pits, and enclosures with bottom access are also confined spaces. They prohibit natural ventilation, are potential sources of gas generation and can keep gases from escaping, causing a potentially hazardous atmosphere.
When in Doubt, Expect the Worst.
To recognize a confined space, you must fully understand the potential hazards. The normal safety hazards of the workplace, whether mechanical, electrical or physical, are complicated by the limited area of most confined spaces Precautions must be taken. But the most serious threat to the health and safety of the worker concerns the atmosphere of the confined space.