PVC wafer check valves from Asahi/America are installed on the discharge side of pumps to prevent backflow flooding. The body, disc and stopper assembly are machined from solid PVC plate stock, which conforms to ASTM D1784 Cell Classification 12454A and ISO 5752 face-to-face dimensions. They are installed by slip-fitting the valve between two mating flanges. The valve body automatically centers on the mating flanges, once the stud pack is installed. The design of the disc and stopper permits the disc to fully open when upstream flow is present, without interfering with schedule piping and mating flanges. Valves are available in 3 through 12 inches, with EPDM seals and no spring. All 3- to 8-inch valves operate at a maximum pressure of 150 psi; 10- and 12-inch at 90 psi and up to 120 degrees F. Optional seals in FKM and an ETFE-coated stainless steel spring are available. 800/343-3618; www.asahi-america.com.