The swing check valve shall be
operated in a manner to avoid the following troubles;
1) formation of excessive high surge pressure as a result of valve
closing, and
2) rapid fluctuating movement of valve closing member. The
excessively high surge pressure by valve closing is prevented by
closing the valve fast enough not to develop a significant reverse
flow on a sudden shutoff which is a source of the surge pressure.
Thus, the closing speed of valve should match closely with the
speed of forward flow retard.
The rapid fluctuating movement of valve closing member must be
avoided to prevent the moving valve parts from excessive wear
which may result in early failure of valve.
Such movements can be precluded by sizing the valve to a flow rate
which forces the closure member not to move.
The swing check valve can
also be mounted to the vertical position, provided the disc should
not reach the valve position. However, the closing moment of disc
by weight is very low in fully-opened position, so the valve tends
to close late. In order to overcome
