Respirator Components

Respirators are grouped by how they fit to the face, the type of treatment the breathing atmosphere receives, and the relation of the pressure inside the facepiece to the atmosphere during inhalation. Components of a respirator include the facepiece, inhalation and exhalation valves, headbands, and a connection for an air purifying filter, cartridge, or a source of supplied air.

Facepieces are classified as either loose-fitting or tight fitting. Loose-fitting facepieces include hoods and helmets that cover the head completely. Tight-fitting facepieces include the following types:

• Quarter masks cover the mouth and chin (most commonly found on dust and mist respirators).
• Half masks fit over the nose and under the chin.
• Full facepieces cover the face from the forehead to the chin.

Breathing air is either filtered or supplied. Air purifying respirators filter contaminants from the air, while supplied air respirators provide breathable air from an uncontaminated source. Supplied air respirators are typically selected when the concentration of contaminant is high or unknown.

The pressure inside the facepiece, along with any facial movement, can allow contaminants to infiltrate the respirator. Negative pressure respirators mean that the pressure inside the respirator during inhalation is less than the pressure outside the respirator. Positive pressure respirators mean that the pressure inside the respirator is always greater than the pressure outside the respirator.

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