R 408.41456 Definitions; M to W.

Rule 1456. (1) "Man lock" means a chamber through which employees pass from 1 air pressure environment into another. (2) "Materials lock" means a chamber through which materials and equipment pass from 1 air pressure environment into another. (3) "Occupied tunnel" means any tunnel entered by 1 or more employees. (4) "Pressure" means a force acting on a unit area, usually shown as pounds per square inch (p.s.i.). (5) "Qualified person" means a person who, by possession of a recognized degree, certificate, or professional standing, or who by extensive knowledge, training, and experience, has successfully demonstrated the ability to solve or resolve problems relating to the subject matter, the work, or the project. (6) "Safety screen" means an airtight and watertight diaphragm placed vertically across the upper part of a compressed air tunnel between the face and bulkhead in order to restrain sudden flooding of the crown of the tunnel between the safety screen and the bulkhead, thus providing a means of refuge and exit from a flooding or flooded tunnel. (7) "Shaft" means a vertical or inclined opening excavated below ground level, that is for the purpose of tunnel operations. (8) "Tunnel" means a generally horizontal excavation or facility more than l4 inches in diameter, width, or height and more than 6 feet in length below ground or water. Facilities used for the acquisition of minerals, ores, and fossil fuels, which are commonly known as mines, are excluded from this definition. (9) "Working chamber" means the space or compartment under air pressure in which the work is being done.