ABSTRACT
Fig. 10.6 shows the layout of a land drainage pumping station equipped with axial flow unit. The purpose of the siphon arrangement is to obviate any risk of the flap valve, which is otherwise necessary, jamming and reverse flow taking place in the pipe, the pump then functioning as a turbine. A butterfly valve is fitted which serves to break the vacuum in the siphon. This valve is slightly off balance towards the open position and directly delivery ceases the valve opens and admits air, thus preventing any reverse flow. The pumping plant may be made fully automatic by means of electrodes which dip into the suction well and control the operation of the pump.
