CHECK VALVES ARE  2 TYPES:
SWING CHECK VALVES 
WAFER CHECK VALVES 
THAT ARE AVAILABLE IN A RANGE OF SIZES AND PRESSURES. CHECK VALVES ARE SINGLE-DIRECTION FLOW VALVES USED TO ALLOW UNLIMITED FLOW IN ONE DIRECTION AND TO RESTRAIN FLOW IN THE OPPOSITE DIRECTION
~ GENERAL DESIGN : API 600, API 602, API 6D
~ SIZE : 1/ 4 ” to 28 ”
~ STANDARD RATINGS
. 150LB, 300LB, 600LB, 900LB, 1500LB, 2500LB, JIS 10K, 20K, PN 10, PN 16
~ MATERIAL : ASTM A216 WCB, ASTM A105, ASTM A350-CF8