CONFINED SPACES
In nearly all cases atmospheric testing of permitted confined spaces is required.1 The tests are necessary to
evaluate the hazards of the permit space and verification that conditions within the space are acceptable for
entry.
1. Evaluation and Testing your Permit Required Confined Space. The atmosphere of a confined
space should be analyzed using equipment of sufficient sensitivity and specificity to identify and
evaluate any hazardous atmosphere that may exist or arise, so that appropriate permit entry
procedures can be developed and acceptable entry conditions stipulated for that space. Evaluation
and interpretation of the data and development of the entry procedure should be done by, or
reviewed by, a technically qualified professional (e.g., CTR Safety & Environmental Management
Services, certified industrial hygienist, or registered safety engineer) based on evaluation of all
serious hazards.
2. Testing and Atmosphere Verification of your Permit Required Confined Space. The
atmosphere of a permit space which may contain hazardous atmosphere should be tested for
residues of all contaminants identified by the evaluation testing using permit specified equipment to
determine that residual concentrations at the time of testing and entry are within the range of
acceptable entry conditions. Testing order should be oxygen, flammables, and then toxics.2 Results of
the actual concentrations obtained from the testing should be recorded on the permit in the space
provided adjacent to the stipulated acceptable entry condition.
3. Duration of Testing. Measurement values for each atmospheric parameter should be made for at
least the minimum response time of the test instrument specified by the equipment manufacturer.
4. Testing stratified atmospheres. When monitoring for entries involving a descent into atmospheres
which may be stratified, the atmosphere envelope should be tested a distance of approximately four
(4) feet (1.22 meters) in the direction of travel and to each side. If a sampling probe is used, the
entrant’s rate of progress should be slowed to accommodate the sampling speed and detector
response.
5. Periodically retest. Verify that the atmosphere remains within acceptable entry conditions.3
1. Title 29 Code of Federal Regulations 1910.146, Appendix B.
2. 29 CFR 1910.146 (c)(5)(ii)(C) and (d)(5)(iii)
3. 29 CFR 1910.146 (c)(5)(ii)(F) and (d)(5)(ii)
evaluate the hazards of the permit space and verification that conditions within the space are acceptable for
entry.
1. Evaluation and Testing your Permit Required Confined Space. The atmosphere of a confined
space should be analyzed using equipment of sufficient sensitivity and specificity to identify and
evaluate any hazardous atmosphere that may exist or arise, so that appropriate permit entry
procedures can be developed and acceptable entry conditions stipulated for that space. Evaluation
and interpretation of the data and development of the entry procedure should be done by, or
reviewed by, a technically qualified professional (e.g., CTR Safety & Environmental Management
Services, certified industrial hygienist, or registered safety engineer) based on evaluation of all
serious hazards.
2. Testing and Atmosphere Verification of your Permit Required Confined Space. The
atmosphere of a permit space which may contain hazardous atmosphere should be tested for
residues of all contaminants identified by the evaluation testing using permit specified equipment to
determine that residual concentrations at the time of testing and entry are within the range of
acceptable entry conditions. Testing order should be oxygen, flammables, and then toxics.2 Results of
the actual concentrations obtained from the testing should be recorded on the permit in the space
provided adjacent to the stipulated acceptable entry condition.
3. Duration of Testing. Measurement values for each atmospheric parameter should be made for at
least the minimum response time of the test instrument specified by the equipment manufacturer.
4. Testing stratified atmospheres. When monitoring for entries involving a descent into atmospheres
which may be stratified, the atmosphere envelope should be tested a distance of approximately four
(4) feet (1.22 meters) in the direction of travel and to each side. If a sampling probe is used, the
entrant’s rate of progress should be slowed to accommodate the sampling speed and detector
response.
5. Periodically retest. Verify that the atmosphere remains within acceptable entry conditions.3
1. Title 29 Code of Federal Regulations 1910.146, Appendix B.
2. 29 CFR 1910.146 (c)(5)(ii)(C) and (d)(5)(iii)
3. 29 CFR 1910.146 (c)(5)(ii)(F) and (d)(5)(ii)
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| This page was last updated: March 30, 2009 |
