|
Swing check valve.
The regular swing check is not a good choice in services with frequent flow reversal.
This causes the disc to pound into the seat and wear quickly.
In gritty liquid services a composition disc is required to reduce seat damage.
This valve may be installed vertically or horizontally.
The only concern in mounting this style vertically is that in streams where velocity changes slowly the valve has a tendency to stay opened.
A lever and counter-balance are available to handle this and to allow it to be opened by low pressure fluid.
|
|
Tilting-disc check valve This design is used for streams that frequently change direction of flow.
It will close quicker and seal better with less slamming then the swing check valve.
It has a higher pressure drop with large flow velocities and a lower pressure with small velocities then regular swing check valve.
This style also can be installed horizontally or vertically.
|
|
Lift-check valves These check valves have a disc that is guided.
Spring loaded types can operate in either vertical or horizontal mounting.
The style that lacks the spring must be mounted in such a way as to allow gravity to close disc.
Composition disc valves are available for gritty liquid services.
|
|
Piston-check valve This is a suitable valve where the direction of flow changes frequently.
Due to an integral dash pot pounding from the flow is minimized.
This valve is available with or without a spring.
This valve is not a good choice for gritty services.
|
|
Stop-check valve This is basically a check valve that can be kept closed automatically or manually.
It is typically found between boilers and in steam headers.
|
|
Ball-check valve This valve is usually good for most services.
It can even handle fluids that produce gummy deposits.
The ball is seated by gravity or by back flow pressure.
Since the disc is free to rotate wear is distributed evenly and this all helps to keep the valve seats clean.
|
|
Wafer-check valve Wafer check valves are closed by two semi-circular flaps that are hinged to a center post in the middle of it’s ring shaped body.
The valve is inserted between two flanges.
It is most commonly found in non-fouling liquid services.
Wafer-check valves are also compact and are of a relatively low cost.
A single disc version is also available.
|
