Work history, personal opinion, and company policy seem to often “cloud the mind” and lead to practice, procedures, or opinions regarding Permit-Required Confined Spaces that are in conflict with the actual content of the OSHA regulation. Perhaps the most graphic way to explore this “compliance” gap is by means of the a simple 20 question quiz that will point out some common errors of interpretation sometimes found in both those who enforce the regulation and those who must develop programs to comply with the regulation.

1-20 Questions

1. (True or False)An employer must evaluate all places of work and if PRCS (Permit-Required Confined Spaces) are found, the employer must develop a confined space entry team and address the rescue requirements of the regulation. [Paragraph (k)]

2. (True or False)An employer must maintain a list, directory or database for all PRCS at their facility.

3. (True or False)Continuous ventilation is required for all Permit-Required Confined Space entries.

4. (True or False)A poured concrete dry vault 11-feet deep contains only water shutoff valves for fire-fighting purposes. A ladder is required for entry. This is a Permit-Required Confined Space.

5. (True or False)A state university campus has over five miles of below-ground utility service tunnels carrying steam lines, 220 VAC power, data, etc. The tunnel system is PRCS.

6. (True or False)Contractors are required by 1910.146 to follow the host employer’s PRCS entry program.

7. (True or False)Application of LO/TO (1910.147) allows an employer to reclassify a permit space to Non-Permit status prior to a (c)(7) entry.

8. (True or False)A below-ground utility vault contains a water main and meter. This space is a strong candidate for possible entry by Alternate Procedure (c)(5).

9. (True or False)A below-ground vault near an airport Jet A fuel storage area is tested with an industry standard “four-gas” meter and registers 20.9% O2, 0 LEL methane, 0 CO, 0 H2S. However, an odor of Jet fuel is present. This is a Non-Permit space and entry is OK without PRCS considerations.

10. (True or False)Local exhaust ventilation constitutes adequate ventilation for OSHA’s Alternate Procedure (c)(5).

11. (True or False)Continuous ventilation of a PRCS with a blower of 1500 cfm or greater suspends the need for air testing a confined space.

12. (True or False)A blower and/or hose can be removed temporarily during personnel or equipment entry when an Alternate Procedure entry is underway.

13. (True or False)Cancelled permits must be kept on file for 12 months after completion of the entry and reviewed annually.

14. (True or False)When atmospheric hazards of PRCS exceed limits of “Hazardous Atmosphere,” all entrants must evacuate the space and cease operations.

15. (True or False)Detector tubes are an acceptable methodology for testing atmospheric hazards prior to confined space entry.

16. (True or False)Continuous atmospheric monitoring of Permit-Required Confined Spaces is required during entry operations.

17. (True or False)The atmospheric testing instrument must be calibrated immediately prior to use at a confined space entry operation.

18. (True or False)The oxygen sensor mode of a “four-gas” (CO, H2S, O2, LEL) instrument can be used to estimate interferent gas levels such as argon, CO2, halon, freon, etc.

19. (True or False)A portable “combination” electronic gas detector must be certified intrinsically safe by one or more North American testing laboratories.

20. (True or False)A “four-gas” combination instrument has been factory (and field) calibrated at 50% LEL using methane gas. This unit is accurate to +/- 10% for other gas and vapor LELs.

1-20 Answers

1. (False)Having found PRCS on premises, an employer must identify such spaces, prohibit entry by their employees, and instead may choose to use outside contract personnel for tasks done in such spaces. [The contract should stipulate that the contractor follow a PRCS program and provide rescue capability.]

2. (False)It is required that the cognizant individual (safety director, maintenance supervisor, etc.) know where all PRCS are and their hazards, but no actual list or database is required by OSHA.

3. (False)Ventilation is mandatory under 1910.146 only for “Alternate Procedure” entries (See (c)(5) of regulations). OSHA recognizes ventilation for helping to keep atmospheric hazards “controlled” to safe levels while cautioning that ventilation cannot “eliminate” any hazard.

4. (True and False)Trick question. This space has no “physical hazards” such as machinery and no engulfment hazards. OSHA does not make depth (i.e. fall hazard) a condition of confined space. If air monitoring over a reasonable time period shows clean air (20.9/0/0/0 on a 4-gas meter), the employee could classify this as a Non-Permit Confined Space. [i.e. confined but hazard free.] Alternate Procedure (c)(5) would also be acceptable.

5. (False)Issue 1: Public employee facilities are not covered by Federal OSHA rules unless the state is one of the 23 “State Plan” states. Issue 2: In a “State Plan” state these utility service tunnels are not treated as PRCS. “A Tunnel Entrance Procedure” is written (an SOP), PPE specified for entrants, and an emergency response plan developed, but 1910.146 need not be followed.

6. (False)General Requirement Section (c) paragraphs (8) and (9) require a contractor to follow a PRCS entry program. However, by contract or negotiation the PRCS program may be either that of the host employer or that of the contractor, if both have OSHA-compliant written programs.

7. (False)Hazard elimination of a PRCS requires isolation of the space (such as double block and bleed, blanking, blinding, disconnecting), emptying the space of its contents and lockout/tagout. 1910.147 is only a part of isolation of a space.

8. (True)Underground vaults with standing water may potentially have atmospheric hazards and could pose an engulfment hazard. If the vault is dry and historical air test data is favorable, then it is a strong candidate for (c)(5) “Alternate Procedure” entry.

9. (False)The combustible sensor on a 4-gas portable instrument is the catalytic element (hot wire) type and is usually calibrated by using methane gas (CH4). However, fuel vapor such as diesel, Jet A, and heating oil may require a correction factor multiplier of 5 to 7 times the LEL reading. It would be best to check for fuel vapor with a MOS sensor, hydrocarbon detector tube, or PID before entry operations proceed.

10. (False)CFR 1910.146 (c)(5) requires forced air (positive pressure) ventilation from a clean source outside the space.

11. (False)A pre-entry air test is still required of “Alternate Procedure” (ventilated vault entries) under CFR 1910.146 (c)(5).

12. (False)When a blower stops for any reason, occupants must exit a space being entered under the (c)(5) “Alternate Procedure.”

13. (True)See OSHA CFR 1910.146 (a). Permits must be saved for 12 months, but review of permits can be monthly, quarterly, or annually. Certificates for (c)(5) and (c)(7) entries do not have to be kept on file.

14. (True and False)Trick question. When atmospheric hazards exceed OSHA limits for “Hazardous Atmosphere,” entrants must indeed exit a PRCS. However, the entry supervisor may require additional cleaning or isolation of the space or the use of IDLH-rated PPE by trained entrants supported by a rescue team. Work can continue in IDLH rated spaces when trained personnel use proper PPE.

15. (True)OSHA’s Compliance Directorate Office stated in an interpretation in 1993 that detector tubes and combustible gas indicators were acceptable methods for confined space air testing.

16. (False)Pre-entry testing is mandatory. Thereafter, “periodic” or “as necessary” is allowed. Only for sewer environments does CFR 1910.146 support “continuous atmospheric monitoring.”

17. (True and False)Trick question. CFR 1910.146 requires a portable gas detector to be maintained in accordance with the manufacturer’s instructions. OSHA does not address sensor technology or instrument design and maintenance. You must maintain your instrument consistent with the stated requirements of the owner manual supplied with your monitor.

18. (False)Oxygen sensors are very specific for oxygen (O2) gas. Interferent gases like argon, CO2, halon, etc. must reach about 70,000 ppm before an oxygen deficiency alarm of 19.5% is read by the instrument.

19. (False)CFR 1910.146 does not address electrical equipment approvals for hazardous locations. A properly maintained 20-year-old unapproved device is absolutely acceptable practice. In reality, almost all instruments on the market for the last decade bear one or more third-party approval labels for intrinsic safety.

20. (False)Instrument manuals will show “correction factors” or correction curves for combustible gas sensors in atmospheres other than that used by the factory. Correction factors can routinely be 1.5 to 2.5 and as high as 5 to 7 for kerosene and jet fuel (high flash-point hydrocarbons).

How’d you do?

Note from the author as a former teaching fellow and college professor:
  • 18 or more correct — Congratulations, you are a pro!
  • 14 to 17 correct — time for a review session!
  • Less then 14 correct — sign up for a PRCS seminar or PDC ASAP!