Confined Spaces Definitions

Acceptable entry conditions - the conditions that must exist in a confined space to ensure that employees can safely enter and work within the space.

Attendant - a designated individual stationed outside a permit space who monitors entrants and performs attendant's duties as required by this program.

Blanking or blinding - the absolute closure of a pipe, line, or duct by the fastening of a solid plate (such as a spectacle blind or a skillet blind) that completely covers the bore and that is capable of withstanding the maximum pressure of the pipe, line, or duct with no leakage beyond the plate.

• A blank is designed as a flat plate between two flanges, typically inside the flange bolt pattern. The blank must be sized for full design pressure (maximum non-shock presssure rating) of the line.
• A blind is designed as a bolted flat plate, which can be used to terminate a pipe line.

Confined space - any space that is 1) large enough and so configured that an employee can bodily enter and perform assigned work, 2) has limited or restricted means for entry or exit, and 3) is not designed for continuous employee occupancy.

• Confined spaces include, but are not limited to: storage tanks, pits, vats, vessels, sewer manholes, electrical manholes, vaults, pump or lift stations, septic tanks, boilers, pipelines, tunnels, ventilation and exhaust ducts, trenches, and excavations.

Double block and bleed - the closure of a line, duct, or pipe by closing and locking or tagging two in-line valves and by opening and locking or tagging a drain or vent valve in the line between the two closed valves.

Emergency - any occurrence or event inside or outside of the confined space that could endanger entrants.

Entrant - any authorized employee who enters a confined space, including any part of the employees' body breaking the plane of any opening of the confined space.

Entry Supervisor - the departmental person responsible for determining if acceptable entry conditions are present in a confined space where entry is planned, for authorizing and overseeing entry operations, and for terminating entry as required by this program.

Engulfment - the surrounding of a person by finely divided solids or a liquid. A worker in a storage tank filled with sawdust, for example, could fall into an air pocket, be completely surrounded by sawdust, and suffocate to death.

Ground-fault circuit-interrupter - a device designed to disconnect an electric circuit when it seeks ground through a person or grounded object, thus preventing electric shock and fires.

Hazardous Atmosphere - an atmosphere presenting a potential for death, disablement, injury, or acute illness from one or more of the following causes:

• A flammable gas, vapor or mist in excess of 10% of its' lower flammable limit (LFL),
• An oxygen deficient atmosphere containing less than 19.5% oxygen by volume or an oxygen enriched atmosphere containing more than 23.5% oxygen by volume,
• Airborne combustible dust at a concentration that meets or exceeds its LFL (airborne combustible dust which obscures vision at five feet or less),
• An atmospheric concentration of any substance for which a dose or a permissible exposure limit is published in Subpart G, Occupational Health and Environmental Control, or in subpart Z, Toxic and Hazardous Substances, which could result in an employee exposure in excess of its dose or permissible exposure limit, and that could cause death, incapacitation, impairment of ability to self-rescue, injury or acute illness,
• Any other atmospheric condition that is immediately dangerous to life or health (IDLH).

Hot work permit - the employer's written authorization to perform hotwork operations (e.g. welding, cutting, burning, or heating) capable of providing a source of ignition.

Immediately dangerous to life or health (IDLH) - any condition that poses an immediate or delayed threat to life, or that would cause irreversible adverse health effects or that would interfere with an individual's ability to escape unaided from a confined space.

Inerting - the displacement of the atmosphere in a confined space by a noncombustible gas (such as nitrogen) to such an extent that the resulting atmosphere is noncombustible. Note: This procedure produces an IDLH oxygen-deficient atmosphere that can only be entered using self-contained breathing apparatus (SCBA) and following permit-required confined space entry procedures.

Isolation - the process by which an energy source is removed from service and completely protected against the release of energy and material into the space by such means as: blanking or blinding; misaligning or removing sections of lines, pipes, or ducts; a double block and bleed system; lockout or tagout of all sources of energy; or blocking or disconnecting all mechanical linkages.

LEL/LFL - lower explosive/flammable limit; the minimum concentration of vapor-in-air or vapor-in-oxyten below which propagation of flame does not occure on contact with a source of ignition. Expressed in terms of percentage by volume of gas or vapor in air.

Line breaking - the intentional opening of a pipe, line, or duct that is or has been carrying flammable, corrosive, or toxic material, an inert gas, or any fluid at a volume, pressure, or temperature capable of causing injury.

Local exhaust ventilation - a system used during welding, cutting or other similar operations in confined spaces as necessary to remove harmful gases, smoke and fumes.

Lockout-tagout - placing locks or tags on the energy isolating device (e.g. breaker boxes, control switches, valves, etc.) to prevent the unauthorized reenergization of the device or circuit while work is being performed by personnel. Tags shall indicate that the energy isolated device must not be operated until the tag is removed by the individual(s) that installed the tag.

Non-permit confined space - a confined space which after evaluation is unlikely to have potential hazards, or the hazards have been eliminated by engineering controls.

Oxygen deficient atmosphere - an atmosphere containing less than 19.5% oxygen by volume.

Oxygen enriched atmosphere - an atmosphere containing more than 23.5% oxygen by volume.

PEL - permissible exposure limit; the allowable air contaminant level established by the Occupational Safety and Health Administration (OSHA).

Permit-required confined space - a confined space which after evaluation is found to contain actual or potential hazards which have not been eliminated by engineering controls. Written authorization for entry is required.

Rescue Team - those persons whom the employer has designated prior to any permit-required confined space entry to perform rescues from confined spaces. Blacksburg Volunteer Fire Department is the rescue team for Virginia Tech.

Retrieval System - the equipment used for non-entry rescue of persons from confined spaces, and includes retrieval lines, chest or full body harness, and a lifting device or anchor. A retrieval line is primarily for use in vertical entry confined spaces, and must not be used in confined spaces consisting of horizontal tunnels or spaces where obstructions could increase the hazard to the entrant during emergency retrieval.

Testing - the process by which the hazards that may confront entrants to a confined space are identified and evaluated.

UEL/UFL - upper explosive/flammable limit; the maximum proportion of vapor or gas in air above which flame propagation does not occur. Expressed in terms of percentage by volume of gas or vapor in air.

Zero Mechanical State - the mechanical potential energy of all portions of the machine or equipment is set so that the opening of the pipe(s), tube(s), hose(s) or actuation of any valve, lever, or button will not produce a movement which could cause injury.