Describe a standard negative-pressure facepiece seal check.

Describe a standard negative-pressure facepiece seal check.

• A. The wearer blows into the facepiece to test breathing.
• B. The facepiece is heated to ensure seal.
• C. The user inhales through the cylinder while the valve is open.
• D. With the exhalation valve blocked, the user inhales and the facepiece should collapse slightly against the face with no air leaks around the seal.

Answer: (D)

A negative-pressure seal check tests whether the facepiece forms a proper seal to the face by creating a slight vacuum inside the mask. Block the exhalation valve and gently inhale. The facepiece should collapse slightly against the face, and there should be no air leaks around the seal. This indicates the gasket and fit are good and the wearer can safely proceed in a hazardous environment. If leaks are present, adjust the headbands or position the mask for a better seal. Methods that don’t create this negative pressure condition—like blowing into the facepiece, heating it, or inhaling with the valve open—do not reliably verify a proper seal.

A negative-pressure seal check tests whether the facepiece forms a proper seal to the face by creating a slight vacuum inside the mask. Block the exhalation valve and gently inhale. The facepiece should collapse slightly against the face, and there should be no air leaks around the seal. This indicates the gasket and fit are good and the wearer can safely proceed in a hazardous environment. If leaks are present, adjust the headbands or position the mask for a better seal. Methods that don’t create this negative pressure condition—like blowing into the facepiece, heating it, or inhaling with the valve open—do not reliably verify a proper seal.