Demand Respirator 1 : An atmosphere-supplying respirator that admits breathing air to the facepiece only when a negative pressure is created inside the facepiece by inhalation
University of California (Environmental Health & Safety), Safety & Industrial Hygiene Glossary of Terms, Riverside, CA, USA 2010. http://ehs.ucr.edu/safety/glossary.html, (IndHygS - Amer) {500}