Recognizing Confined Spaces

 Some Confined Spaces Are Easy To Recognize.
    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.