Among all those valve types, the check valve is one of the principal kinds. It’s used to close off piping and to prevent backflow. Backflow occurs when the substance in the pipe flows in the opposite direction when the valve is shut.
There are many types of this type of valves like ball check valves, stop-check valve, cone check valves, and disc check valve and so forth. Learn more about check valves and strainers in detail on http://www.asia-pacifics.com/products_brand/Mueller%20Steam%20Specialty.
The first category is the most common one. A ball in the shell of the valve fits tightly against the face of the valve where the water comes in.
The second type is a product with override control to stop flow no matter flow direction or pressure. It can’t only close in response to backflow or inadequate forward pressure but can also be deliberately shut by an external mechanism, thereby preventing any flow regardless of forwarding pressure.
The third one is similar to ball check valves, but the plug which seals the valve is shaped like a cone. It also can be called a lift check valve in which the disc, sometimes known as a lift, can be lifted up off its seat by higher pressure of inlet or upstream fluid to allow flow into the outlet or downstream side.
The fourth one is the disc valve that’s also known as swing check valve. It operates in precisely the same manner as ball and cone valves, but the plug which settles over the opening is a disk.