User Seal Check

Before each type of fit test, the user must perform a user seal check on the respirator to be tested. The user seal check consists of a negative pressure (inhaling) and positive pressure (exhaling) portion.

For the negative pressure check, the user wears the respirator and closes the inlet opening, either with the palm of his or her hand or by replacing the filter seal. The user then inhales gently so that the facepiece collapses slightly and holds his or her breath for 10 seconds. If the facepiece remains in its collapsed position and no inward leakage of air is detected, the check is considered successful. If the user cannot cover the inlet opening with his or her hand, a latex or nitrile glove may be used to cover the opening instead.

For the positive pressure check, the user wears the respirator and closes off the exhalation valve with his or her hand or a latex or nitrile glove. In many cases, this involves first removing the exhalation valve cover and then replacing it after the test. While the exhalation valve is covered, the user exhales gently. If slight positive pressure can be built up and there is no apparent outward leakage of air, the check is considered successful.

If the manufacturer of a respirator specifies different user seal check procedures, those procedures may be used instead, provided they are equally effective.

To learn more about Respiratory Protection visit our Cal/OSHA Respiratory Protection Online Training web page.