Working Principle of Check Valve
Check valves are primarily used in pipes where media flow in one direction, allowing media to flow in one direction only, and preventing reverse flow to prevent accidents.Check valves are automatic valves, with the disc open under the action of fluid pressure flowing in one direction; when fluid flows in the opposite direction, the disc acts on the seat by the fluid pressure and the weight of the disc, thereby cutting off the flow
Check valves can be divided into threaded check valves, flanged check valves and welded check valves in connection form, and clamp check valves in 4 types.
Check valves are divided into lifting check valves, swing check valves and butterfly check valves according to their structure.Lift check valves can be divided into vertical check valves and horizontal check valves.Swing check valves are divided into three types: single-disc, double-disc and multi-disc.Butterfly check valves are straight-through check valves.
Swing check valves have a pin-shaft mechanism and a door-like disc resting freely on a sloping seat surface.To ensure that the disc is seated properly each time, the disc is set in a pin mechanism so that the disc has sufficient swing space and that the disc truly and fully contacts the seat.With swing check valves fully open, fluid pressure is virtually unhindered, so pressure drop across the valves will be smaller.The discs can be made entirely of metal, or can be metal inlayed with leather, rubber, or synthetic cover, depending on the applicability requirements.
The disc of the lift check valve is seated on the seating face on the valve body.Except for the free lift of the disc, the rest of the lift check valve is like a globe valve, where fluid pressure lifts the disc from the seating face and media return causes the disc to fall back onto the seat and cut off flow.Like globe valves, the flow path through the lift check valve is narrow, so the pressure drop through the lift check valve is greater than that through the swing check valve.Depending on the applicable conditions, the disc may have an all-metal mechanism or may have a rubber pad or rubber ring mounted on the disc holder.
The following points should be noted in the installation of check valves:
1. Attention should be paid to the direction of media flow during installation in accordance with the direction of arrow indicated on the valve body to prevent accidents.
2. The lifting vertical disc check valve shall be installed in the vertical pipe with the medium flowing from bottom to top.
3. The lifting horizontal disc check valve shall be installed in the horizontal pipeline.
4. Do not load check valves in the pipeline. Large check valves should be supported independently so that they are not piped.