R 408.41455 Definitions; A to H.

Rule 1455. (1) "Atmospheric pressure" means the pressure of air at sea level, usually 14.7 p.s.i.a. (1 atmosphere) or zero p.s.i.g. (2) “Auger boring and jacking” means the mechanical removal of soil by use of a rotating auger and cutting head and simultaneously installing pipe or other lining where the section of lining is installed at the opening of the excavation and is jacked or otherwise forced toward the advancing face. (3) "Auger tunnel" means a tunnel that is excavated by use of a continuous flight auger system, with or without a sleeve or other type of liner. (4) "Bulkhead" means an airtight structure separating the working chamber from free air or from another chamber under a lesser pressure than the working pressure. (5) "Caisson" means either a generally vertical foundation unit below grade or a chamber placed in the ground or water for excavating earth and in which it is possible for a person to work under air pressure greater than atmospheric pressure to excavate material below water level. (6) "Cofferdam" means a temporary structure used to control the flow of water and other material during construction operations. (7) "Competent person" means a person who is experienced and capable of identifying existing and predictable hazards in the surroundings or under working conditions that are hazardous or dangerous to an employee, and who has the authority and knowledge to take prompt corrective measures to eliminate hazards. (8) "Compressed air" means an environment that has a pressure greater than atmospheric pressure. (9) "Decanting" means a method used for decompressing under emergency circumstances. In this procedure, the employees are brought to atmospheric pressure with a very high gas tension in the tissues and then immediately recompressed in a second and separate chamber or lock. (10) "Emergency lock" means a lock designed to hold and permit the quick passage of an entire shift of employees. (11) "Escape-only respirator" means a respirator intended to be used only for emergency exit. (12) "High air" means air pressure used to supply power to pneumatic tools and devices.