Powered Air Purifying Respirator (PAPR)
The air purifying respirators depend on the wearer inhaling to draw the air through the respirator filter. The powered air purifying respirator (PAPR) uses a battery-powered blower that passes the contaminated air through the filter. The face covering can be a half-face mask or a full-face mask with an air flow rate of greater than 4 cfm (cubic feet per minute) for a tight fitting face-piece while 6 cfm is necessary for a loose fitting PAPR. Under normal conditions of use, the worker is supplied with more air than he/she can breathe so that the inside of the face-piece is under positive pressure and no contaminated air can leak in. Under positive pressure, all leakage should be outward rather than inward.