Stanford University

Permit-Required Confined Spaces

Confined spaces are:

  • Large enough (and so configured) that an employee can bodily enter and perform assigned work
  • Limited or restricted for entry or exit (e.g. tanks, vessels, silos, storage bins, hoppers, vaults, and pits)
  • Not designed for continuous employee occupancy

Note that all three conditions must be present for a space to be considered a confined space.

Permit-required confined spaces (permit spaces) have at least one of the following characteristics:

  • Contain, or have the potential to contain, a hazardous atmosphere
  • Contain a material that has a potential for engulfing an entrant
  • Have an internal configuration such that an entrant could be trapped or asphyxiated by inwardly converging walls, or by a floor that slopes downward and tapers to a smaller cross section
  • Contain any other recognized serious safety or health hazard

Note that if any of the above characteristics is present, the space shall be classified as a permit-required confined space.

All employees who will enter permit-required confined spaces (including entrants, attendants, and supervisors) shall receive training in confined space procedures. Training must occur:

  • Before assignment to confined space operations
  • When duties change
  • When a new hazard is present
  • When entry procedures change

These and other pertinent definitions are included in the Cal/OSHA Confined Spaces Regulations.

Stanford provides confined space guidance to:

  • Prevent employee injury, illness, or death resulting from confined space and permit-required confined space operations
  • Define a confined space and permit-required confined space
  • Identify hazards commonly associated with permit-required confined space entry and rescue
  • Train Stanford University employees who will enter confined spaces
  • Maintain records
  • Comply with the OSHA regulatory requirements for confined spaces

The Confined Space Program shall conform to Cal/OSHA requirements, which requires a written program. Where the word “shall” is used in this subtopic, requirements are mandatory by regulation.

  1. Authorized entrants

    Authorized entrants enter and work in permit-required confined spaces. All authorized enrants shall comply with the following requirements:

    • Know the hazards associated with the space
    • Use personal protective equipment correctly
    • Maintain communication with the attendant
    • Alert the attendant of warning signs or symptoms of exposure to a dangerous situation, or when detecting a prohibited condition (i.e. any condition in the permit-required confined space that is not allowed during the authorized entry period).
    • Exit the permit-required confined space as quickly as possible whenever:
      • Ordered by an attendant or entry supervisor
      • Experiencing symptoms of exposure
      • A prohibited condition is detected
      • An evacuation alarm is sounded


    An attendant is the person stationed outside the permit space. Attendants monitor authorized entrants and perform the duties listed below. The attendant is stationed at (and shall remain outside of) the permit-required confined space whenever authorized entrants are in the space. Attendants shall:

    • Know the hazards associated with the permit-required confined space
    • Know possible behavioral effects, signs, or symptoms of hazard exposure
    • Continuously maintain an accurate count of authorized entrants
    • Remain outside the permit-required confined space during entry operations until relieved by another attendant
    • Maintain continuous and effective communication with authorized entrants
    • Monitor inside and outside the permit-required confined space, as necessary
    • Order authorized entrants to evacuate immediately if any of the following conditions occur:
      • A prohibited condition is detected
      • Behavioral effects of hazards exposure are detected in an authorized entrant
      • A situation outside the space that could endanger the authorized entrants is detected
      • The attendant cannot effectively and safely perform all required duties
    • Know the emergency response plan and how to summon assistance
    • Warn unauthorized persons who are in (or about to enter) the permit-required confined space to leave
    • Inform the authorized entrants and the entry supervisor if unauthorized persons have entered the permit space
    • Perform non-entry rescue
    • Perform no other duties that may interfere with monitoring and protecting authorized entrants

    Entry supervisors

    The entry supervisor is responsible for:

    • Determining if acceptable entry conditions are present at a permit-required confined space where entry is planned
    • Authorizing entry
    • Overseeing entry operations
    • Terminating entry as required by the program

    Entry supervisors shall:

    • Know the hazards associated with the space
    • Verify that specified testing has been done, and that equipment and procedures specified by the permit are in place
    • Sign the permit and authorize entry
    • Terminate the entry and cancel the permit if the operations have been completed, or if an unacceptable or prohibited condition arises in or near the permit-required confined space
    • Verify that rescue services are available and that the means for summoning additional services are working properly
    • Remove unauthorized persons who enter, or attempt to enter, the permit-required confined space
    • Determine and ensure that operations comply with the terms and conditions on the permit

    An entry supervisor may also serve as an attendant or as an authorized entrant, as long as that person is trained and equipped for the duties of entry supervisor. The duties of entry supervisor may be passed from one individual to another during the course of an entry operation.

  1. Permit requirements

    The confined space entry permit certifies that specific precautions have been taken before employees enter the space.

    • The entry supervisor shall sign the permit when conditions for safe entry have been met.
    • The permit shall be posted or otherwise made available to authorized entrants.
    • The duration of the permit may not exceed the time required to complete the operation.
    • The permit may be revoked if entry conditions become unacceptable.
    • In order to make appropriate revisions to the Confined Space Program, any problems encountered should be noted on the permit.

    Contents of permit

    Permits must contain the following information:

    • Identification of the permit-required confined space
    • Purpose of the entry
    • Date and authorized duration of the entry
    • Identification of the authorized entrant(s), attendant(s), and entry supervisor
    • Description of the hazards of the permit-required confined space
    • Measures taken to isolate the space and to eliminate or control hazards before entry
    • Acceptable entry conditions
    • Results of initial and periodic tests, including identification of the person conducting the tests and when the tests were made
    • The rescue and emergency services that can be summoned and the means for summoning them
    • Communications procedures used by the authorized entrant(s) and the attendant(s)
    • Special equipment required (e.g. personal protective equipment, testing equipment, etc.)
    • Any other relevant information
    • Any additional permits, such as those required for hot work
    • The entry supervisor’s signature or initials

    Recordkeeping for entry permits

    Supervisors shall retain canceled entry permits for at least one year.

Pre-Job Requirements
  1. Instrumentation

    Campus department personnel use several types of atmospheric monitoring instruments. EH&S must approve all types of instruments.

    Toxic gas monitor requirements

    • The gas monitor must be capable of monitoring for oxygen, combustible gases, hydrogen sulfide (H2S), and carbon monoxide (CO).
    • All gas monitoring equipment must be capable of real-time monitoring.
    • Manually check all alarms and operation modes before each use.
    • Maintain and calibrate instruments according to the manufacturers’ specifications.
    • Do not use instruments that are out of calibration or not working properly.

    Toxic gases other than H2S and CO

    In the event that toxic gases other than H2S and CO may be present:

    • Contact the Industrial Hygiene/Safety Program at EH&S for assistance (3-0448).
    • Do not enter the space until authorized by EH&S.

    Controlling sources of ignition

    Before any work is done which might release vapors, all sources of ignition, such as open flames or welding, must be eliminated.

    Purging and ventilating

    The permit-required confined space shall be purged, inerted, flushed, or ventilated as necessary to eliminate or control atmospheric hazards. If a confined space contains a sludge or other residue, tests positive for combustible or toxic elements, or indicates an oxygen deficiency or enrichment, purge the space with fresh air and provide positive ventilation before and throughout entry into the space.


    All energy sources in the permit-required confined space that are potentially hazardous shall be isolated to protect against the release of energy and material. These sources include electrical, pneumatic, chemical, mechanical, and hydraulic systems.


    Barriers to prevent individuals from falling into a permit-required confined space shall be provided.

    Retrieval systems

    Retrieval systems shall be used whenever an authorized entrant enters a permit space unless the retrieval equipment would increase the overall risk of this entry or would not contribute to the rescue of the entrant. Retrieval systems must be at the site during all permit-required confined space operations and shall meet the following requirements:

    • Each entrant shall use a chest or full body harness with a retrieval line (or use wristlets, if they are safer).
    • The retrieval line must be attached to a mechanical device or fixed point outside the space. A mechanical device (e.g., retrieval winch attached to a tripod or davit arm) shall be available to retrieve personnel from vertical type permit spaces more than 5 feet deep.

    Only use extraction devices specifically manufactured for the purpose of rescue. Do not use hoist devices if they are not intended for human rescue.


    • Equipment for communication by appropriate means (e.g. voice, radio, or rope signals) shall be provided.
    • Direct voice-to-voice communication alone should not be relied upon, unless the personnel working in the confined area are at all times in the line of sight of the standby personnel.
    • Communication equipment must be employed during the entire permit-required confined space operation.

    Prohibited conditions

    In the permit-required confined space, a prohibited condition is any condition not allowed by the permit during the authorized entry period. No person may enter a permit-required confined space if any of the following conditions are present, or if personnel are in the space:

    • Air monitoring results indicate the oxygen level is less than 19.5% or more than 23.5%, the atmosphere exceeds 10% of the LEL (lower explosive limit), or toxic gases or vapors are detected
    • The toxic gas monitor alarm sounds
    • Strong or unusual odors are detected, or a chemical leak is suspected
    • A vehicle is left running near the space which could introduce exhaust into the space
    • The attendant leaves his or her post
    • Any equipment fails (e.g. personal protective equipment, monitoring equipment, or rescue equipment)
    • Personnel in the space begin to exhibit dizziness, lightheadedness, confusion, or other unusual symptoms

    If any of these conditions are present, operations must be stopped and the space must be evacuated.

Emergency and Rescue Procedures
  1. Self-rescue and attendant rescue

    Self-rescue and attendant rescue are the lowest levels of emergency response and the only methods approved for Stanford University employees. The following actions shall take place if an emergency or prohibited operation occurs in a permit-required confined space:


    If the entrant is uninjured and in full command of his or her faculties, he or she shall perform self-rescue and evacuate the space.

    Attendant rescue

    • Employees shall not enter a permit-required confined space to attempt rescue.
    • If the entrant is unable to perform self-rescue and has not suffered severe trauma (e.g. a deep wound or fracture), the attendant shall rescue the entrant from outside the confined space, using retrieval equipment located outside the space.
    • If the entrant has suffered severe trauma, or must be immobilized before evacuating the space, the attendant shall contact an outside agency for rescue (see below).

    Rescue by outside agency (Palo Alto Fire Department)

    Stanford University uses an outside agency, the Palo Alto Fire Department (PAFD), to perform rescue operations.

    • The University must provide the PAFD with a copy of the Confined Space Entry Program.
    • The PAFD shall be informed of the hazards they may confront while performing rescues at the University.
    • The PAFD shall be given access to all permit spaces at least once per year to develop rescue plans and practice rescues.


    If entrants have been exposed to chemicals, the SDS (safety data sheet) shall be made available as soon as possible to the medical facility treating the exposed worker.

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