Respirator Components

Respirators are grouped by how they fit to the face, the type of treatment the breathing atmosphere receives, and the relationship 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 made of flexible molded rubber, silicone, neoprene, or other materials. Rubber or woven elastic head straps are attached and buckle together at the back of the head or form a continuous loop of material.

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

The breathing air for respirators 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. With negative pressure respirators, the pressure inside the respirator during inhalation is less than the pressure outside the respirator. With positive pressure respirators, the pressure inside the respirator is always greater than the pressure outside the respirator.

To learn more about MSHA Part 48 training requirements visit our MSHA Part 48 Subpart B Surface Mining Online Training web page.