Confined Or Enclosed Space
For purposes of this paragraph, “confined or enclosed space” means any space having a limited means of egress, which is subject to the accumulation of toxic or flammable contaminants or has an oxygen deficient atmosphere. Confined or enclosed spaces include, but are not limited to, storage tanks, process vessels, bins, boilers, ventilation or exhaust ducts, sewers, underground utility vaults, tunnels, pipelines, and open
top spaces more than four (4) feet in depth such as pits, tubs, vaults, and vessels.
Source: State of Wyoming Occupational Safety and Health Rules and Regulations for Oil and Gas Well Drilling, Revised January 8, 2013. Regulations