Backwater Valve for gravity sanitary drainage system connected to municipal sanitary sewers or septic tanks.
Material SpecificationsThe assembly comprises numerous parts. The following is a brief description of the main components.
1. Gate - Manufactured from stainless steel type 304 with full port opening and integral closing stopper.
2. Body - Two cast iron halves, designed to bolt together to enclose gate. Cast iron shall be Class 25 to ASTM A48. Both sections are equipped with barrels suitable for mechanical coupling to upstream and downstream sections of pipe. Out (or downstream) fitting equipped with full port opening. Each half incorporates a continuous groove around the circumference of the opening to accept an O-ring. These O-rings act to seal against the gate.
3. Spacer - Stainless steel gasket placed between the two body halves to permit the (thinner) gate to slide within the two halves of the body.
4. Expansion chamber - Flexible PVC diaphragm.
5. Counterweight Plate, Plate Weight Holder, and Rod - Counterweight Plate is affixed to the top of the expansion chamber using a threaded rod equipped with nuts. The nuts compress the top surface of the expansion chamber between the counterweight plate on top and the plate weight holder on the bottom. The rod is connected to the top of the gate. Expansion chamber Counterweight Plate is made of cast iron.
6. Clamping Ring - Clamps the bottom skirt of the expansion chamber to the circumference of the body, forming a watertight seal. This seal prevents waste water which enters the expansion chamber through the downstream port under surcharge conditions from leaking out of the expansion chamber.
7. Cover - Polyethylene cylinder which is positioned over the expansion chamber to protect it and constrain its expansion under surcharge conditions.
8. Maintenance Handle - Tee shaped handle used to attach to stem in center of counter weight plate to exercise valve during annual maintenance.
