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    Confined Space

    Definition

    An enclosed or largely enclosed space, not designed for continuous occupancy, where entry can expose workers to risks such as fire, asphyxiation or drowning.

    Editorial definition: The QHSE Standard, updated 3 October 2026 · https://qhsetech.com/glossary/confined-space

    Scope: UK and US definitions differ: the UK ties it to specified risks, US OSHA to limited entry or exit and a separate permit-required class. Check the applicable regime.

    Example for your evaluation: Ask how a demonstration records the avoidance decision, test readings and entrant count for one entry.

    Sources checked: . Examples are editorial illustrations.

    How UK and US rules define a confined space

    There is no single definition. HSE describes a confined space under the Confined Spaces Regulations 1997 as one that is enclosed or largely enclosed and has a reasonably foreseeable specified risk to workers, and lists the specified risks as fire, explosion, loss of consciousness, asphyxiation and drowning. Size and shape are not the test: HSE's examples range from small restrictive areas to large structures such as grain silos. In the United States, 29 CFR 1910.146 treats a confined space as one that a worker can bodily enter, that has limited or restricted means of entry or exit, and that is not designed for continuous occupancy.

    Both systems then separate ordinary confined spaces from those needing the strictest controls. In OSHA's terms a permit-required confined space has a potential hazardous atmosphere, a risk of engulfment, an internal shape that could trap an entrant, or another recognised serious hazard. The employer must evaluate the workplace, post warnings, and, if employees will enter, keep a written permit-space programme. HSE reduces its approach to three duties: avoid entry where possible, for example by doing the work from outside; follow a safe system of work if entry cannot be avoided; and put adequate emergency arrangements in place before the work starts. HSE adds that it is not enough to rely on the emergency services.

    Where an entry permit is required under 1910.146, it must identify the space, the purpose and duration of entry, the authorised entrants, attendant and entry supervisor, the hazards and isolation measures, the acceptable entry conditions and test results, the rescue and communication arrangements, and the equipment needed, with any other permit such as hot work. Attendants stay outside and keep a count of entrants, and the standard sets expectations for rescue capability and practice. OSHA addresses confined spaces in separate standards for general industry, maritime and construction, so check which applies. This page is general information, not advice on a particular space.

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    What a confined-space record holds in software

    • A register of spaces on site: location, description, why each is classed as confined or permit-required, and the date the classification was last reviewed.
    • For each space, the hazards identified (atmosphere, engulfment, trapping shape, energy sources, temperature) and the control chosen against each.
    • Entry permits showing purpose, duration, entrants, attendant, supervisor, isolations, test readings with time and instrument, and cancellation.
    • Gas-testing and monitoring records, including the instrument, its calibration or function-check status, and readings before and during entry.
    • The rescue plan and its test records: who rescues, how quickly, with what equipment and communications, and the date of the last practice.
    • A live entry log that shows who is inside the space at any moment, so the headcount does not depend on memory.

    Confined space, enclosed space and permit-required space

    A confined space is not simply a small room, and a large tank can qualify. Nor is every confined space permit-required: in OSHA's terms the stricter class applies only where one of the listed hazards is present, and a space can be reclassified when its hazards are removed or its use changes. In UK terms the test turns on specified risks, so classification depends on what can reasonably be foreseen, not on the name or size of the space. A confined-space entry permit is also one kind of permit within the wider permit-to-work system, not a replacement for the risk assessment.

    A hypothetical example: a drainage chamber inspection

    This case is invented to illustrate the record and describes no real site. A contractor has to inspect a below-ground drainage chamber. The first question in the planning record is whether entry is needed at all. A camera on a pole can capture the condition of two of the three chambers, so those are inspected from outside. The third has a defect that needs repair, so entry is planned. The assessment notes a possible oxygen-poor or toxic atmosphere because the chamber connects to a sewer, and the entry permit names the isolation of the inlet, the readings required before and during entry, an attendant who stays at the top, a retrieval line and the rescue arrangement, including who calls the rescue team and the expected response time.

    On the day, the first reading is outside the agreed limits. The permit is not issued, ventilation is added, and the reading is repeated. The second reading is acceptable and entry starts with continuous monitoring. Twenty minutes in, the monitor alarms, the attendant calls the entrant out with the agreed signal, and entry stops. The permit is cancelled with the reason recorded, and the space stays in the register as permit-required with a note that the ventilation plan needs a different design. The record made the stopping point clear.

    Common misunderstandings about confined spaces

    • A space is not safe because it has been entered before. Atmospheres can change with the work and with neighbouring processes. HSE's introduction cites a case in which oxygen depletion in a crane compartment overcame four workers, two of whom died.
    • A permit does not make a space safe. It records and communicates the checks and controls; isolation, ventilation, testing and rescue still have to be done in the space.
    • An attendant is not a rescuer who goes in. Under 1910.146 attendants stay outside, keep the count of entrants, monitor conditions and summon rescue.
    • A rescue plan that depends on the emergency services arriving in time is not enough by itself. HSE states that it is not enough to rely on them, and OSHA expects the employer to evaluate whether a rescue service can respond in a timely way.

    How a confined space relates to other glossary terms

    Confined-space entry uses several other controls at once, which is why it appears beside permits, isolations and protective equipment.

    • Permit to work: the system within which an entry permit sits, with its issue, handover and cancellation steps.
    • Lockout/tagout: isolating energy sources before entry; inflows and moving equipment are separate questions from the atmosphere.
    • PPE: respiratory and retrieval equipment is one layer of protection, used after avoidance, isolation and ventilation have been considered.
    • Hierarchy of controls: avoiding entry altogether is the first control, ahead of any equipment worn inside the space.

    Records and evidence that usually exist for a confined space

    • The space register and the classification decision, with the regime applied.
    • The assessment showing whether entry could be avoided and why it could not.
    • Entry permits, including test results, isolations, named roles and cancellation.
    • Rescue plans, the evaluation of the rescue service and records of practice.
    • Training and competence records for entrants, attendants and supervisors.

    What a software tool needs to capture for confined spaces

    • A space register with classification, location and hazards, and a prompt to review the classification when use or configuration changes.
    • A required question on whether entry can be avoided, answered before a permit can be raised.
    • Permit fields for the roles, duration, isolations and required readings, with other permits such as hot work linked rather than retyped.
    • Readings captured with time and instrument identity, and a visible flag when a reading is outside the limits the site has set in its procedure.
    • A live entrant count that the attendant can update, and a closing step that confirms everyone has left.
    • Competence checks for named entrants, attendants and supervisors.

    Catalog profiles documenting confined-space entry

    Each profile documents a confined-space capability in its record. Gas testing and rescue are physical controls that no record can perform.

    Same rule for every product: tagged “Permit to Work”, “Permits to Work (PTW)”, “Control of Work” or “Industrial Safety” or assigned primary category “EHS Management” or “Lone Worker Safety”, with a sourced confined-space entry or gas monitoring capability in its record, or one the vendor stated to us, labelled as vendor-stated. Documented and conditional capabilities qualify; check the linked scope before treating a module as included.

    Ordered by how closely our sources document this process, not by quality. Sponsored placements are labelled. How lists are ordered

    All 5 matching profiles are shown. Documentation review, not hands-on testing or a claim of compliance.

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    Frequently asked questions

    Is every tank or vessel a confined space?

    Not automatically. In the UK the test turns on whether a specified risk is reasonably foreseeable in an enclosed or largely enclosed space. Under US OSHA it turns on limited entry or exit and design for continuous occupancy, with a separate permit-required class. Record the assessment and the regime applied.

    Does an entry permit replace the risk assessment?

    No. The assessment decides whether entry is needed and which controls apply. The permit coordinates and records them for one entry.

    Who should carry out rescue?

    Decide and test the rescue arrangement before entry, and do not rely only on the emergency services. HSE requires emergency arrangements before work starts, and OSHA expects the employer to evaluate whether a rescue service can respond in a timely way.

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