1. (1) Confined spaces where dangerous air contaminants have been present, are present or could be introduced from potential sources shall not be entered by any person for any reason until the atmosphere of such confined spaces has been tested and found free of dangerous air contaminants. Any such confined space shall be continuously maintained free of dangerous air contaminants during any period of occupancy. If, however, due to emergency conditions any such confined space cannot be cleared of dangerous air contaminants by mechanical ventilation or equivalent means, any person entering such confined space shall be provided with and shall use an approved air line respirator, approved hose mask or approved self-contained breathing apparatus.

2. (2) Whenever a confined space is to be entered, a person who has been designated as a safety monitor shall function as required by this Part (rule). A confined space shall not be entered unless there is at least one other person in addition to the required safety monitor ready to render assistance in an emergency when alerted. Such additional person shall be located within 100 feet unobstructed walking distance from and not more than one floor above or one floor below the access opening of such confined space. The assigned duties of such additional person shall be such that they will not prevent him from responding immediately to an emergency when alerted.

   (b) Preparation for entering a confined space.

   Prior to entering any confined space, the following steps shall be taken to insure the safety of the person entering:

3. (1) Any contents shall be removed, emptied or drained from the confined space insofar as is possible and the interior shall be purged by water or other equivalent means.
4. (2) The person entering the confined space or a designated qualified person shall lock out the circuit breakers or switches of all electrically operated equipment such as agitator drives, pumps and similar equipment which is connected to or affects the confined space and could affect the health and safety of any person in the confined space. The keys for such locks shall be retained by the person entering the confined space.
5. (3) All manhole and clean-out covers shall be removed and the openings maintained clear of any obstructions.
6. (4) All input lines which discharge into the confined space shall be disconnected and capped or provided with line blank flanges. The use of a single in-line valve shut-off is prohibited as the sole means of isolating the confined space from any input line. However, the use of a double in-line valving arrangement with a vent in between the two valves is acceptable provided that dangerous air contaminants are not created by such venting.
7. (5) Tests in the confined space for the presence of dangerous air contaminants or lack of sufficient oxygen, or both, where the threat of each condition exists shall be made by a designated person who is qualified to conduct such tests by training and experience. Such tests shall be performed using calibrated equipment of a type suitable for the air contaminants involved. If such tests indicate that air contaminants in excess of the concentrations listed in subpart 12-3 of this Part (rule) are present in the confined space, the space shall be purged by mechanical ventilation until a subsequent test indicates that the air contaminant concentration is in compliance with subpart 12-3 of this Part (rule). If more than one type of air contaminant is known to be present or could be introduced in the confined space, additional tests shall be made for each contaminant. A confined space containing air contaminants which may develop an explosion hazard shall be purged by mechanical ventilation until tests indicate that the concentration of air contaminants in the confined space is not more than 25 percent of the lower explosive level of such air contaminants and that there is sufficient oxygen available in the confined space. In lieu of purging by mechanical ventilation, an inert atmosphere may be maintained in the confined space, provided that control devices are used to insure that combustion or ignition of material, including gases, cannot occur. Whenever an inert atmosphere is maintained in a confined space, every occupant shall be equipped with an approved self-contained breathing apparatus, an approved air line respirator or an approved hose mask. Every occupant shall leave the confined space immediately in the event of an interruption of the air supply to the breathing apparatus. The inert atmosphere shall be prevented from contaminating all other work areas, including the area of the access opening to the confined space and adjacent areas. Maintenance of the inert atmosphere shall in no way interfere with or prevent the emergency escape of an occupant from such a confined space.
8. (6) The mechanical ventilation system shall be so designed that the contaminants or contaminated air is transported to some safe location, without recirculation, and the replacement entry air does not contain dangerous air contaminants, but does contain sufficient oxygen. The provisions of this paragraph shall also apply to the exhausting of an inert atmosphere.

9. (7) Any person entering a confined space shall be provided with and shall use the following additional safety equipment: Exception:

   1. (i) Where the least dimension of any access opening to a confined space is less than 24 inches, approved wrist straps or approved noose-type wristlets shall be worn. Where the least dimension of such access opening is greater than 24 inches, either an approved life belt, approved safety harness, approved wrist straps or approved noose-type wristlets shall be worn.

   2. (ii) A lifeline, as specified by the provisions of Industrial Code Part (Rule No.) 23, shall be attached to such life belt, approved safety harness, approved wrist straps or approved noose-type wristlets with the other end securely anchored outside the confined space.

      Exception:

      Where such a lifeline attached to approved wrist straps or approved noose-type wristlets interferes with the performance of the work duties of the person occupying the confined space, such lifeline complete with safety snaps may be disconnected from the wrist straps or wristlets provided the lifeline safety snap remains within three feet of the person in the confined space for quick attachment to the wrist straps or wristlets.

   3. (iii) A safe means of ingress and egress, such as a portable ladder, provided such means will not obstruct the access opening.
   4. (iv) An explosion-proof battery-operated portable light in good working order.

   5. (v) Non-sparking striking, chipping, hammering or cutting tools and equipment where the confined space may contain explosive or flammable air contaminants.

      (c) Safety monitors.

10. (1) A person designated as a safety monitor shall be stationed at the access opening of any confined space while such space is occupied for any reason. The safety monitor shall maintain visual contact with every occupant in the confined space where the construction of the confined space permits, or shall have continuous knowledge of the activities and well-being of every occupant of the confined space via verbal communication or other positive means at all times. Such safety monitor may assist an occupant of a confined space in such light duties as handling tools or supplies or removing containers of refuse or debris provided that these tasks do not interfere with his primary duty as a safety monitor.
11. (2) The safety monitor shall be an alert, competent person, fully capable of quickly summoning the assistance of a person or rescue team for the administration of emergency first aid treatment if required.
12. (3) The safety monitor must be physically able to assist such summoned person or rescue team in the extrication of an occupant from a confined space under emergency conditions.

13. (4) The following emergency equipment shall be available to the safety monitor or rescue personnel for use if required.

    1. (i) Approved air line respirator, approved hose mask or approved self-contained breathing apparatus.
    2. (ii) Explosion-proof battery-operated portable light in good working order.
    3. (iii) Safety equipment as specified in subpart 12-1, section 12-1.9, subdivision (b), paragraph (7), subparagraphs (i) and (ii) of this Part (rule).

14. (5) Such emergency equipment shall be located at the access opening of the confined space or not more than 15 feet from such opening.

    (d) Operations requiring continuous testing.

    If the nature of the work to be performed produces or has the potential to produce dangerous air contaminants as specified in this Part (rule), continuous testing shall be performed. If such tests indicate evidence of dangerous air contaminants exceeding the concentrations listed in subpart 12-3 of this Part (rule) or in quantities greater than 25 percent of the lower explosive level, the occupants shall be ordered to evacuate the confined space immediately.

    (e) External alarm signal.

    Outside of every occupied confined space there shall be an audible alarm signal device located within 15 feet of the access opening. Such device may be of the portable type and shall be maintained in good working order. When actuated, such audible alarm shall be louder than the general background noise level and should be capable of being heard clearly by any person located within 100 feet of the access opening. In case of an emergency in a confined space, the safety monitor shall immediately actuate the alarm signal. In no case shall the safety monitor or other rescue personnel enter the confined space without first actuating the alarm signal and, secondly, putting on his personal protective equipment.

    (f) Illumination.

    There shall be installed and maintained an independent substitute emergency lighting system in addition to the principal lighting system in any area where a confined space is located and which is entered frequently for cleaning and maintenance purposes. Such substitute emergency lighting system shall operate automatically upon failure of the principal system and shall be capable of providing distinct illumination for a period of at least 30 minutes of all access openings of confined spaces as well as of the general surrounding area and exits. Whenever the principal lighting system fails, the confined spaces shall be evacuated immediately. Where any confined space is to be entered infrequently for inspection or similar purposes, sufficient quantities of battery-powered lights in good working order shall be provided to afford distinct illumination at every access opening and its surrounding area and exit. These lights shall be capable of providing illumination for a period of time of at least one hour.

(a) General.