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12
Positive and Negative Pressure User Seal Checks
Positive Pressure Seal Check (Figure 13)
fig. 13
Close off the exhalation valve by pushing firmly on the center of the exhalation valve cover with the heal of
one hand. It may be difficult to close the exhalation valve completely, therefore you must blow out or exhale
hard. If the facepiece bulges slightly and no air leaks between the face and facepiece are detected, a proper
seal has been obtained. If air leakage is detected around the faceseal, reposition the respirator on the face
and/or readjust the tension of the straps to eliminate leakage and perform another user seal check. If you
cannot achieve a proper fit, do not enter the contaminated area. See your supervisor.
Negative Pressure Seal Check (Figure 14)
fig. 14
The negative pressure seal check is the recommended user seal check method for this respirator. With the
palm of your hand, cover the inlet port on the outside of the cartridge. Inhale gently. If the facepiece
collapses slightly, and no air leaks between the face and facepiece are detected, a proper fit has been
obtained. If air leakage is detected, reposition the respirator on the face and/or readjust the tension of the
straps to eliminate leakage and perform another user seal check. If you cannot achieve a proper fit, do not
enter the contaminated area. See your supervisor.
Quantitative and Qualitative Fit Testing
The effectiveness of a respirator will be reduced if it is not fitted properly. Therefore, either quantitative or
qualitative fit testing must be conducted prior to the respirator being issued and used.
Note: Fit testing is both a U.S. Occupational Safety and Health Administration (OSHA) and Canadian
requirement.