Air is forced up from the buoy counterweight tube during downward motion causing the balls to seal the air ports in the valve, thus forcing the air to flow into the whistle.
空气在向下运动过程中受到浮标向上的推力，使阀球将阀门里的气舱密封住，这样迫使气流进入雾笛。
2
The fluid surface forcing control system applied on counter pressure casting is built based on the combined digital valve as the main flow control component.