This rule covers enclosed spaces that may be entered by
employees. It does not apply to vented vaults if the employer makes a
determination that the ventilation system is operating to protect employees
before they enter the space. This rule applies to routine entry into enclosed
spaces in lieu of the confined space entry requirements contained in
437-002-0146(4) through
(11). If, after the employer takes the
precautions given in 437-002-2304 and
437-002-2319 of Division 2/RR,
the hazards remaining in the enclosed space endanger the life of an entrant or
could interfere with an entrant's escape from the space, then entry into the
enclosed space must meet the permit-space entry requirements of
437-002-0146(4) through
(11), Confined spaces, in Division 2/J.
(1) Safe work practices. The employer
must ensure the use of safe work practices for entry into, and work in,
enclosed spaces and for rescue of employees from such spaces.
(2) Training. Each employee who enters an
enclosed space or who serves as an attendant must be trained in the hazards of
enclosed-space entry, in enclosed-space entry procedures, and in enclosed-space
rescue procedures.
(3) Rescue
equipment. Employers must provide equipment to ensure the prompt and safe
rescue of employees from the enclosed space.
(4) Evaluating potential hazards. Before any
entrance cover to an enclosed space is removed, the employer must determine
whether it is safe to do so by checking for the presence of any atmospheric
pressure or temperature differences and by evaluating whether there might be a
hazardous atmosphere in the space. Any conditions making it unsafe to remove
the cover must be eliminated before the cover is removed.
Note to paragraph (4): The determination called
for in this paragraph may consist of a check of the conditions that might
foreseeably be in the enclosed space. For example, the cover could be checked
to see if it is hot and, if it is fastened in place, could be loosened
gradually to release any residual pressure. An evaluation also needs to be made
of whether conditions at the site could cause a hazardous atmosphere, such as
an oxygen-deficient or flammable atmosphere, to develop within the
space.
(5) Removing covers.
When covers are removed from enclosed spaces, the opening must be promptly
guarded by a railing, temporary cover, or other barrier designed to prevent an
accidental fall through the opening and to protect employees working in the
space from objects entering the space.
(6) Hazardous atmosphere. Employees may not
enter any enclosed space while it contains a hazardous atmosphere, unless the
entry conforms to the confined space standard,
437-002-0146 Confined spaces, in
Division 2/J.
(7) Attendants.
While work is being performed in the enclosed space, an attendant with
first-aid training must be immediately available outside the enclosed space to
provide assistance if a hazard exists because of traffic patterns in the area
of the opening used for entry. The attendant is not precluded from performing
other duties outside the enclosed space if these duties do not distract the
attendant from: monitoring employees within the space or ensuring that it is
safe for employees to enter and exit the space.
Note to paragraph (7): See
437-002-2319 Underground
electrical installations, for additional requirements on attendants for work in
manholes and vaults.
(8)
Calibration of test instruments. Test instruments used to monitor atmospheres
in enclosed spaces must be kept in calibration and must have a minimum accuracy
of ±10 percent.
(9) Testing
for oxygen deficiency. Before an employee enters an enclosed space, the
atmosphere in the enclosed space must be tested for oxygen deficiency with a
direct-reading meter or similar instrument, capable of collection and immediate
analysis of data samples without the need for offsite evaluation. If continuous
forced-air ventilation is provided, testing is not required provided that the
procedures used ensure that employees are not exposed to the hazards posed by
oxygen deficiency.
(10) Testing
for flammable gases and vapors. Before an employee enters an enclosed space,
the internal atmosphere must be tested for flammable gases and vapors with a
direct-reading meter or similar instrument capable of collection and immediate
analysis of data samples without the need for off-site evaluation. This test
must be performed after the oxygen testing and ventilation required by
paragraph (9) of this rule demonstrate that there is sufficient oxygen to
ensure the accuracy of the test for flammability.
(11) Ventilation and monitoring for flammable
gases or vapors. If flammable gases or vapors are detected or if an oxygen
deficiency is found, forced-air ventilation must be used to maintain oxygen at
a safe level and to prevent a hazardous concentration of flammable gases and
vapors from accumulating. A continuous monitoring program to ensure that no
increase in flammable gas or vapor concentration above safe levels occurs may
be followed in lieu of ventilation if flammable gases or vapors are initially
detected at safe levels.
Note to paragraph (11): See the definition of
"hazardous atmosphere" for guidance in determining whether a specific
concentration of a substance is hazardous.
(12) Specific ventilation requirements. If
continuous forced-air ventilation is used, it must begin before entry is made
and must be maintained long enough for the employer to be able to demonstrate
that a safe atmosphere exists before employees are allowed to enter the work
area. The forced-air ventilation must be so directed as to ventilate the
immediate area where employees are present within the enclosed space and must
continue until all employees leave the enclosed space.
(13) Air supply. The air supply for the
continuous forced-air ventilation must be from a clean source and may not
increase the hazards in the enclosed space.
(14) Open flames. If open flames are used in
enclosed spaces, a test for flammable gases and vapors must be made immediately
before the open flame device is used and at least once per hour while the
device is used in the space. Testing must be conducted more frequently if
conditions present in the enclosed space indicate that once per hour is
insufficient to detect hazardous accumulations of flammable gases or vapors.
Note to paragraph (14): See the definition of
"hazardous atmosphere" for guidance in determining whether a specific
concentration of a substance is hazardous.
Note to
437-002-2304: Entries into
enclosed spaces conducted in accordance with the requirements of
437-002-0146 (4) through
(11), Confined spaces, are considered as
complying with 437-002-2304 of Division
2/RR.
