Exhaust Valve 2 : Valve devices that allow one way air flow in order to prevent protective suits from over-pressurizing. Conversely, they also prevent outside chemicals from entering the suit
DuPont (The Miracles of Science), Literature & Technical Information, Industrial Personal Protection Glossary, Wilmington, DE, USA 2010http://www2.dupont.com/Personal_Protection/en_ HK/tech_info/glossary_industrial.html, (IndPP - Amer) {49}