Yuken Check Valves

These valves allow free flow in one direction, while preventing flow in the reverse direction. They are used to prevent reversed flow, and two check valve types, in-line and right angle, are available. The poppet opens when the inlet pressure exceeds the spring force. The pressure at which the poppet starts to open is called cracking pressure. Check valves are often incorporated in sequence valves or pressure reducing valves to let them open in one direction and bypass the free flow in the reverse direction.

Figures 4.10 and 4.11 show the in-line and right angle check valves, respectively. Figure 4.12 shows their pressure drop characteristics.

In-Line Check Valve