Confined space decision flowchart

A space is a confined space when it is large enough for a worker to enter and perform work, has limited or restricted means for entry or exit, and is not designed for continuous worker occupancy. Employers should evaluate the size, access points, and intended occupancy of the space when making this determination. See the Permit-Required Confined Space Decision Flow Chart in Appendix A to 1910.146 and the definitions and requirements in 1910.146 for more detail.

A confined space becomes a permit-required confined space if it contains or has the potential to contain a hazardous atmosphere, a material that could engulf an entrant, an internal configuration that could trap or asphyxiate, or any other recognized serious safety or health hazard. If any of these conditions exist or could reasonably develop, the space must be treated as a PRCS under 1910.146 and the decision steps in the Appendix A flow chart should be followed.

Yes — but only when continuous forced air ventilation alone is sufficient to maintain a safe atmosphere and the employer follows the standard's requirements for that exception. 1910.146 contains an exception that allows a space with a hazardous atmosphere to be entered without a permit if the hazard is eliminated by continuous forced air ventilation and the employer documents and maintains appropriate monitoring and procedures. Consult 1910.146 and the Appendix A decision flow chart to confirm the conditions and controls required for this exception.

Treat it as a permit-required confined space until testing and evaluation show it is safe. Unknown or untested atmospheres must be assumed hazardous; the employer must test and identify atmospheric hazards and apply the permit-space procedures in 1910.146 before allowing entry, as outlined in the Appendix A flow chart.

Engulfment is a hazard where loose material or liquid in a space can flow over and bury or suffocate an entrant (for example, grain, sand, or liquids). If a confined space presents a risk of engulfment, it is a permit-required confined space and must be managed under the permit-space procedures in 1910.146; the Appendix A flow chart specifically directs you to treat spaces with engulfment potential as PRCS.

Yes — an employer may reclassify a permit space to a non-permit confined space but only when the employer can demonstrate that all hazards have been eliminated and that no hazard remains or can be introduced during entry. The reclassification must meet the criteria and procedures in 1910.146, and the Appendix A flow chart helps determine when elimination and reclassification are appropriate.

Yes — when entry is made into a permit-required confined space, the employer must have a trained attendant stationed outside the space to monitor entrants, communicate, and initiate rescue if needed. The attendant and their duties are required by 1910.146, and the Appendix A flow chart incorporates the need for attendant responsibilities in deciding permit-space actions.

You must test for oxygen concentration, flammable gases/vapors, and potential toxic contaminants — in that order — and continue monitoring as required to ensure conditions remain safe. Employers should follow the atmospheric testing and monitoring guidance and procedures in 1910.146 and use the Appendix A flow chart to determine when testing is required.

Yes — any recognized serious hazard inside a confined space, including hazardous energy sources (mechanical, electrical), chemical hazards, or other safety hazards, makes the space a permit-required confined space and requires permit-space procedures under 1910.146. The Appendix A flow chart directs employers to treat spaces with such hazards as PRCS.

An entry permit must document the space to be entered, purpose of entry, date and duration, authorized entrants, attendants, entry supervisor, hazards identified, measures used to isolate and control hazards, results of initial and periodic atmospheric testing, required rescue/emergency services, and any special equipment or procedures used. Employers must complete and follow these permit requirements set out in 1910.146 and the related guidance in the Appendix A flow chart.

Follow the flow chart step-by-step: first decide whether the space is a confined space, then ask whether any hazardous atmospheres, engulfment, internal configuration, or other serious hazards exist or could develop; if any do, the space is a permit-required confined space and a permit is needed. The Appendix A decision flow chart and the text of 1910.146 together provide the questions, possible controls, and required steps for deciding whether a permit must be issued.

Employers must ensure that adequate rescue and emergency services are available and that rescuers are trained and equipped to perform confined-space rescue without creating additional hazards. The employer must evaluate rescue capability and provide on-site or off-site rescue service as required by 1910.146; use the Appendix A flow chart to identify when rescue requirements apply.

Yes — the host employer must inform contractors of the hazards, the host's permit-space program, and any precautions or procedures required; both host and contractor must coordinate to ensure safe entry under [1910.146]. See 1910.146 for host/contractor responsibilities and the Appendix A flow chart for decision steps related to contractor entries.

Employers must train entrants, attendants, and entry supervisors so they understand the hazards, safe entry procedures, use of equipment (including PPE and testing instruments), and emergency and rescue procedures. Training must be provided before assignments and refreshed as necessary to maintain proficiency, as required by 1910.146; the Appendix A flow chart supports these training needs by clarifying when permit-space measures apply.

If an employer can completely eliminate all hazards (including atmospheric and other serious hazards) through isolation or other methods so that no hazard remains or can be introduced during entry, the space may be reclassified as a non-permit confined space. However, if any hazard remains or could reasonably develop, a permit is required. Follow the reclassification and elimination criteria in 1910.146 and consult the Appendix A decision flow chart when evaluating elimination and reclassification.

Continuous atmospheric monitoring may be used where it provides reliable assurance that atmospheric conditions remain within acceptable limits for the duration of the entry; employers must ensure monitors are calibrated, appropriate for the contaminants of concern, and alarmed for prompt response. The need for continuous versus periodic monitoring and the monitoring requirements are addressed in 1910.146 and should be applied consistent with the guidance in the Appendix A flow chart.

Yes — employers must retain entry permits and related records as required by the standard (including documentation of atmospheric testing, rescue arrangements, training, and procedures) and make them available for inspection as required by 1910.146. Review the recordkeeping and permit-retention provisions in 1910.146 to determine specific retention requirements.

The employer is responsible for evaluating each space, determining whether it meets the definition of a confined space and whether hazards present make it a permit-required confined space, and implementing the appropriate permit or non-permit procedures. This responsibility and the decision steps are set out in 1910.146 and the Appendix A flow chart.

You must treat the space as a permit-required confined space and use permit procedures because the hazard could reasonably develop during entry; simply ventilating before entry is not sufficient if the hazard can return. The Appendix A flow chart and 1910.146 require continuous control and monitoring when hazards can reoccur, and if they cannot be reliably prevented, a permit and full PRCS procedures are required.