Automatic air venting device for electromagnetic plunger pump

摘要

An automatic air venting device including a venting cylinder communicating with the pressure side of an electromagnetic plunger pump down-stream of a discharge valve thereof, a valved plunger fitted in the venting cylinder for sliding reciprocatory movement, a valve mounted at an end of the valved plunger on the side of a return port, a valve seat located at the return port and adapted to be engaged by the valve when the internal pressure of the pump is above a predetermined value during operation of the pump, a spring urging the valve to be brought out of engagement with the valve seat, and a leak passage formed in the valved plunger for bringing the pressure side of the pump into communication with the return port when the valved plunger is urged by the spring to move in a direction in which the valve is brought out of engagement with the valve seat. When the internal pressure of the valve drops below the predetermined value as the pump draws air at initial stages of operation or draws air bubbles entrained in the liquid during operation of the pump, the valve is brought out of engagement with the valve seat and the pressure side of the pump is communicated with the return port through the leak passage, the air or air bubbles in the liquid are rapidly vented through the return port.