Key Terms

Adjacent piping: Refers to a device such as a pipe, line, duct, or conduit that is connected to a confined space or is so located as to allow a substance from within the device to enter the confined space.

Attendant: The name given to an individual stationed outside one or more permit spaces who monitors the authorized entrants and who performs all attendant's duties assigned in the employer's permit space program.

Authorized entrant: Refers to an employee who is authorized by the employer to enter a permit space.

Blank: Refers to a solid plate installed through the cross-section of a pipe, usually at the flanged connection.

Blanking: Refers to the absolute closure of adjacent piping by fastening across its bore a solid plate or cap that completely covers the bore and can withstand the maximum pressure of the adjacent piping.

Confined space: A confined space has limited or restricted means for entry or exit and is not designed for continuous occupancy. Confined spaces include, but are not limited to, tanks, vessels, silos, storage bins, hoppers, vaults, pits, manholes, tunnels, equipment housings, ductwork, and pipelines.

Double block and bleed: Refers to the closure of adjacent piping by locking out a drain or vent in the open position in the line between two locked-out valves in the closed position.

Entry Permit: An administrative tool used to document the completion of a hazard assessment for each confined space entry.

Harmful substance: Refers to a hazardous product or a substance that may have a harmful effect on a worker in a confined space.

High hazard atmosphere: Refers to an atmosphere that may expose a worker to risk of death, incapacitation, injury, or acute illness, or that may otherwise impair the ability of the worker to escape unaided from a confined space in the event of a failure of the ventilation system or the worker's respirator.

Inerting: A process of intentionally flooding the atmosphere inside a confined space with an inert gas, such as nitrogen, to eliminate the hazard of ignition of flammable vapors inside the confined space. The process creates an oxygen-deficient atmosphere.

Low hazard atmosphere: Refers to an atmosphere that is already known or shown by pre-entry testing to contain clean respirable air immediately prior to entry to a confined space. Furthermore, a low hazard atmosphere is not likely to change during the work activity, as determined by a qualified person after consideration of the design, construction, and use of the confined space; the work activities to be performed; and all engineering controls.

Moderate hazard atmosphere: Refers to an atmosphere without clean respirable air that is nonetheless not likely to impair the ability of the worker to escape unaided from a confined space in the event of a failure of the ventilation system or the worker's respirator.

To learn more about Confined Space Competent Person/Supervisor visit our Confined Space Competent Person/Supervisor Online Training web page.