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Determination of known exhalation valve damage using negative pressure user seal-check methods on full-face respirators.

Delaney-L; McKay-R
American Industrial Hygiene Conference and Exposition, May 20-25, 2000, Orlando, Florida. Fairfax, VA: American Industrial Hygiene Association, 2000 May; :45
Employees wearing respirators in industrial settings rely on users' positive- and negative-pressure seal checks to assess respirator fit. However, few studies have been performed to determine the adequacy of user seal checks in detecting poor-fitting or damaged respirators. In this study, the negative-pressure user seal check (NPUSC) method was evaluated for its ability to adequately detect known exhalation valve damage. The damage included a warped valve, a valve with three slits, and a valve with a small amount of glue. Twenty-six test subjects, wearing full-facepiece respirators, were asked to perform a NPUSC. Their responses as to whether they passed or failed the NPUSC were compared with fit-testing results from two quantitative fit-test methods. In addition, in-mask pressure differentials were measured during the performance of NPUSCs using equipment developed in the UC respirator laboratory. This method was developed as a more reliable technique to assess the ability of respirator wearers to properly conduct user seal checks. The data were analyzed to determine whether the NPUSC procedure is an effective method for detecting known exhalation valve damage. All test subjects reported passing the NPUSC with the undamaged valve. With the respirator equipped with the warped valve, 95% of test subjects reported passing NPUSCs. With the respirator equipped with the valve with adhesive, 65% reported passing. All fit factors were below the OSHA recognized pass/fail criteria, except one test with the respirator equipped with the slit valve. Results from the in-mask pressure measurements confirmed that 98% of all user seal checks were properly conducted. It was unable, however, to detect respirator leakage. In conclusion, NPUSC performed by the user rarely identified damaged exhalation valves.
Respirators; Respiratory-equipment; Leak-prevention; Equipment-reliability; Pressure-testing; Laboratory-testing; Face-masks; Failure-analysis; Testing-equipment; Personal-protective-equipment; Performance-capability; Materials-testing
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American Industrial Hygiene Conference and Exposition, May 20-25, 2000, Orlando, Florida