29 CFR 1910.146: Permit-required confined spaces
The official text is on the eCFR. This page maps how the section is organized, quotes the paragraphs our ASP, CSP practice questions are built on, and gives free questions you can try. Text below is quoted from the eCFR, current as of 2026-10-14; the section was last amended 2023-01-13.
How 29 CFR 1910.146 is organized
- (a) Scope and application1 paragraph
- (b)47 paragraphs
- (c) General requirements47 paragraphs
- (d) Permit-required confined space program (permit space program)41 paragraphs
- (e) Permit system9 paragraphs
- (f) Entry permit18 paragraphs
- (g) Training8 paragraphs
- (h) Duties of authorized entrants12 paragraphs
- (i) Duties of attendants19 paragraphs
- (j) Duties of entry supervisors7 paragraphs
- (k) Rescue and emergency services19 paragraphs
- (l) Employee participation3 paragraphs
- [Appendix B to § 1910.146]7 paragraphs
- [Appendix C to § 1910.146]73 paragraphs
- [Appendix E to § 1910.146]8 paragraphs
- [Appendix F to § 1910.146]40 paragraphs
Paragraphs our practice questions cite most
Counted across the 17 live PassCited questions built on this section. This reflects our question bank, not the real exam.
“(3) Is not designed for continuous employee occupancy.”
“(5) Any other atmospheric condition that is immediately dangerous to life or health.”
“(ii) If it is necessary to enter the permit space to eliminate hazards, such entry shall be performed under paragraphs (d) through (k) of this section. If testing and inspection during that entry demonstrate that the hazards within the permit space have been eliminated, the permit space may be reclassified as a non-permit confined space for as long as the hazards remain eliminated.”
“(iv) Ensure that affected employees practice making permit space rescues at least once every 12 months, by means of simulated rescue operations in which they remove dummies, manikins, or actual persons from the actual permit spaces or from representative permit spaces. Representative permit spaces shall, with respect to opening size, configuration, and accessibility, simulate the types of permit spaces from which rescue is to be performed.”
“(v) Debrief the contractor at the conclusion of the entry operations regarding the permit space program followed and regarding any hazards confronted or created in permit spaces during entry operations.”
Free practice questions on 29 CFR 1910.146
Question 1
A plant plans to declassify a tank by relying on a portable blower that keeps the atmosphere within safe limits while employees work inside. The safety coordinator says that this counts as eliminating the atmospheric hazard, so the tank can be treated as a non-permit space under the declassification provisions. How should this be evaluated?
Show answer and source
Answer: D. Incorrect, because controlling atmospheric hazards through forced air ventilation does not constitute elimination of the hazards
The standard says that control of atmospheric hazards through forced air ventilation does not constitute elimination of the hazards. Entry relying on ventilation alone is handled under paragraph (c)(5), not by declassification. The 15-minute figure is not in the standard.
Answer D rests on
29 CFR 1910.146(c)(7)(ii)(opens ecfr.gov in a new tab)“Control of atmospheric hazards through forced air ventilation does not constitute elimination of the hazards.”
Question 2
A crew is preparing to enter a process vessel for cleaning. The agitator motor has been locked out, and a blind has been installed in the corrosive feed line. A second line carrying a toxic solvent is still connected to the vessel and is controlled only by one closed valve. The supervisor wants the vessel to be completely protected against the release of energy and material into the space before entry. Which action is needed to finish isolating the vessel?
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Answer: A. Place a double block and bleed system on the solvent line, or blank or blind it
The standard describes isolation as complete protection against release of energy and material, achieved by means such as blanking or blinding or a double block and bleed system. A single closed valve does not meet this, so the solvent line still needs one of those measures. Ventilation, an attendant, and monitoring only react to or dilute a release and do not prevent it.
Answer A rests on
29 CFR 1910.146(b)(5)(opens ecfr.gov in a new tab)“Isolation means 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.”
Question 3
A plant's permit-required confined space (a process vessel) has a hazardous atmosphere that is controlled by continuous forced-air ventilation, plus an engulfment hazard from a product line that is blanked off. A supervisor proposes to declassify the vessel as a non-permit confined space by relying on the ventilation and the blank, and to record the basis in a signed, dated certification. Which response is correct under the standard?
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Answer: C. Declassification is not supported, because controlling atmospheric hazards with forced air ventilation does not count as eliminating them
Reclassification under (c)(7) requires that all hazards be eliminated, and the standard states that forced air ventilation controls atmospheric hazards but does not eliminate them. A certification cannot substitute for actual elimination, so the paperwork does not make declassification valid here.
Answer C rests on
29 CFR 1910.146(c)(7)(ii)(opens ecfr.gov in a new tab)“Control of atmospheric hazards through forced air ventilation does not constitute elimination of the hazards.”
Where it shows up in exam prep
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Other Part 1910 sections
- 29 CFR 1910.1020: Access to employee exposure and medical records
- 29 CFR 1910.1030: Bloodborne pathogens
- 29 CFR 1910.1053: Respirable crystalline silica
- 29 CFR 1910.106: Flammable liquids
- 29 CFR 1910.119: Process safety management of highly hazardous chemicals
- 29 CFR 1910.120: Hazardous waste operations and emergency response
This is a study aid, not legal advice or an official interpretation. Always check the current eCFR text. Original practice questions, not real exam items. PassCited is not affiliated with or endorsed by BCSP.