Atmospheric Testing

DOE-EM-STD-5503-94

from foreign objects entering the space. If it is in a traffic area, adequate barriers should be

erected.

13.9. ATMOSPHERIC TESTING

Atmospheric test data is needed prior to entry into any confined space. Atmospheric testing is

required for two distinct purposes: evaluation of the hazards of the permit space and verification

that acceptable conditions exist for entry into that space. If a person must go into the space to

obtain the needed data, then Standard Confined Space Entry Procedures should be followed (i.e.,

rescue team, attendant, entry supervisor). Before entry into a confined space, a qualified person

should conduct testing for hazardous atmospheres. The internal atmosphere should be tested

with a calibrated, direct-reading instrument for the following, in the order given:

Oxygen content,

Flammable gases and vapors, and

Potential toxic air contaminants.

Testing equipment used in specialty areas should be listed or approved for use in such areas. This

listing or approval should be from nationally recognized testing laboratories such as Underwriters

Laboratories or Factory Mutual Systems.

13.9.1. Evaluation Testing

The atmosphere of a confined space should be analyzed using equipment of sufficient sensitivity

and specificity The analysis should identify and evaluate any hazardous atmospheres 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 these data and development

of the entry procedure should be done by, or reviewed by, a technically qualified professional

(e.g., OSHA consultation service, certified industrial hygienist, registered safety engineer, certified

safety professional).

13.9.2. Verification Testing

A confined space which may contain a hazardous atmosphere should be tested for residues of all

identified or suspected contaminants. The evaluation testing should permit specified equipment

to determine that residual concentrations at the time of testing and entry are within acceptable

limits. Results of testing (i.e., actual concentration) should be recorded on the permit. The

atmosphere should be periodically retested to verify that atmospheric conditions remain within

acceptable entry parameters. Initial testing of atmospheric conditions and subsequent tests after a

job has been stopped should be done with the ventilation systems shut down. If the confined

space is vacated for any period of time, the atmosphere of the confined space should be retested

before re-entry is permitted. Further testing should be conducted with ventilation systems turned

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