AWWA C518:2013
AWWA C518:2013 Dual-Disc Swing-Check Valves For Waterworks Service Gives minimum requirements for dual-disc swing-check valves, 2-in. (50-mm) through 48-in. (1,200-mm) NPS for clean water having a pH range from 6 to 10 and a temperature range of 33 degrees-125 degree