Acceptable Entry Conditions
The conditions that must exist in a permit space to allow entry and to ensure that employees involved with a permit-required confined space entry can safely enter into and work within the space.
An individual stationed outside one or more permit spaces who monitors the authorized entrants and who performs all attendant's’ duties assigned in the permit space program.
An employee who is authorized by the employer to enter a permit space.
Blanking or Blinding
The absolute closure of a pipe, line, or duct by the fastening of a solid plate 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 space that meets the following criteria: Is large enough and so configured that an employee can bodily enter and perform work and has limited or restricted means for entry or exit and is not designed for continuous employee occupancy. Examples include sewers, silos, pits, vaults tanks etc.
Double Block and Bleed
The closure of a line, duct or pipe by closing and locking or tagging a drain or vent valve in the line between the two closed valves.
Any occurrence (including any failure of hazard control or monitoring equipment) or event internal or external to the permit space that could endanger entrants.
The surrounding and effective capture of a person by a liquid or finely divided (flowable) solid substance that can be aspirated to cause death by filling or plugging the respiratory system or that can exert enough force on the body to cause death by strangulation, constriction, or crushing.
The action by which a person passes through an opening into a permit-required confined space. Entry includes ensuing work activities in that space and is considered to have occurred as soon as any part of the entrant's body breaks the plane of an opening into the space.
The written or printed document that is provided by the employer to allow and control entry into a permit space.
The person (such as the department supervisor, foreman, or crew chief) responsible for determining if acceptable entry conditions are present at a permit space where entry is planned, for authorizing entry and overseeing entry operations, and for terminating entry as required by this section. Note: An entry supervisor also may serve as an attendant or as an authorized entrant, as long as that person is trained and equipped as required by this program for each role he or she fills. The duties of entry supervisor may be passed from one authorized individual to another during the course of an entry operation.
An atmosphere that may expose employees to the risk of death, incapacitation, impairment of ability to self-rescue, injury, or acute illness from one or more of the following causes:
- Flammable gas, vapor, or mist in excess of 10% of its LEL;
- Airborne combustible dust at a concentration that meets or exceeds 10% of its minimum explosive concentration;
- Atmospheric oxygen concentration below 19.5% or above 23.5%;
- Atmospheric concentration of any substance for which a dose or a PEL is published in 29 CFR 1910.100 or Title 8 CCR 5155 and which could result in employee exposure in excess of its dose or PEL;
- Any other atmospheric condition that is immediately dangerous to life or health.
Hazardous Atmosphere Only Space
A confined space in which the only hazard posed is an actual or potential hazardous atmosphere, which can be controlled by continuous, forced ventilation.
Hot Work Permit
Employer's written authorization to perform hot work operations (for example, riveting, welding, cutting, burning, and heating) capable of providing a source of ignition.
Immediately Dangerous to Life or Health (IDLH)
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 permit space.
The process by which a permit space 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.
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.
The placement of a lockout device on an energy isolating device, in accordance with an established procedure, ensuring that the energy isolating device and the equipment being controlled cannot be operated until the lockout device is removed.
Lower Explosive Limit (LEL)
Also known as the lower flammable limit (LFL), this is the minimum concentration of a combustible/flammable gas or vapor in air that will ignite if an ignition source is present.
NonPermit Confined Space
A confined space that does not contain or, with respect to atmospheric hazards, have the potential to contain any hazard capable of causing death or serious physical harm.
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.
Permissible Exposure Limit (PEL)
The maximum permitted 8-hour time-weighted average concentration of an airborne contaminant. An employee exposure to an airborne contaminant in a workday, expressed as an 8-hour TWA concentration, shall not exceed the specified OSHA or Cal/OSHA PEL for that substance.
Permit-Required Confined Space or Permit Space
A confined space that has one or more of the following characteristics:
- Contains or has a potential to contain a hazardous atmosphere;
- Contains a material that has the potential for engulfing an entrant;
- Has an internal configuration such that an entrant could be trapped or asphyxiated by inwardly converging walls or by a floor which slopes downward and tapers to a smaller cross-section;
- Contains any other recognized serious safety or health hazard.
The equipment (including a retrieval line, chest or full-body harness, wristlets, if appropriate, and a lifting device or anchor) used for non-entry rescue of persons from permit spaces.
The placement of a tagout device or an energy-isolating device, in accordance with an established procedure, to indicate that the energy isolating device and the equipment being controlled may not be operated until the tagout device is removed.
The process by which the hazards that may confront entrants of a permit space are identified and evaluated. Testing includes specifying the tests that are to be performed in the permit space.
Threshold Limit Value (TLV)
Airborne concentrations of substances, which represent conditions under which it is believed that nearly all workers may be repeatedly exposed day after day without adverse effect. The three categories of TLVs established by the American Conference of Governmental Industrial Hygienists (ACGIH) include:
Time-Weighted Average (TWA)
The TWA air concentration of a toxic contaminant to which the average worker may be exposed for an 8-hour workday or 40-hour work week over extended periods of time without apparent injurious or deleterious health effect.
Short Term Exposure Limit (STEL)
The maximal concentration to which workers can be exposed for a period of Up to 15 minutes continuously without suffering ill effects, provided that no more than 4 excursions per day are permitted, with at least 60 minutes between exposure periods, and provided that the daily TWATLV is not exceeded. The STEL should be considered a maximum allowable concentration or ceiling, not to be exceeded at any time during the 15 minute excursion period.
Ceiling Limit (CL)
The concentration that should not be exceeded, even instantaneously.