Upward motion of the buoy causes a suction which lifts the balls, thus allowing air to be drawn back down the counterweight tube.
浮标的向上运动则产生吸力，可将阀球提起，这样可允许气流受力并返回至配重管。
2
Seamless copper tube is pressed and drawn.
铜管是压制的和拉制的无缝管。
3
The extrusion process is a traditional method for the TP2 copper tubes, in which continuous casting solid billet is extruded to hollow tube billet firstly and then drawn to tube.