Clapper Valve 1 : (1) A hinged valve that permits the flow of water in one direction only. (2) A check valve in a siamese connection that prevents the escape of water through an unused inlet
Ralph W. Burklin & Robert G. Purington, Fire Terms: A Guide to Their Meaning and Use, National Protection Association, Boston, MA 1980 USA. (Guide: Meaning and Use, Nat Prot Association Fr Srvc - Amer) {457}