This British Standard specifies requirements for cast or forged steel check valves with flanged or
butt-welding ends of the following types:
a) swing, for vertical or horizontal flow (see Figure 1);
b) lift:
i) piston type, for angle or horizontal flow (see Figure 2);
ii) ball type, for angle or horizontal flow (see Figure 3);
iii) ball type, for vertical flow (see Figure 4);
iv) disk type, for vertical flow (see Figure 5).
The terms “vertical”, “horizontal” and “angle” relate to the axes of the body ends.
When swing check valves are used in vertical lines the flow must be in an upward direction. For the
purposes of this standard any line with a slope (upward or downward) of 5° or less is deemed to be
horizontal. In the case of angle pattern valves the inlet should be vertical.