What is the working principle of bathing liquid by head?

Update:01-07-2019
Summary:

(1) When the pump head is depressed and then released, […]

(1) When the pump head is depressed and then released, the compressed spring pushes the piston upward, the air pressure in the space where the spring is located is reduced, and the air pressure in the large bottle presses the liquid upward through the conduit, and pushes the glass beads away. The liquid enters the space in which the spring is located.

    (2) Press the pump head again, the piston moves downwards, and the spring presses the glass beads down to seal the nozzle to prevent the incoming liquid from returning to the large bottle. Press the pump head while the piston moves up a little distance to expose the small hole in the shaft of the piston, and the liquid rises through the small hole.

(3) Loosen the pump head again, the piston moves upward, and the small hole on the counter-shaft of the piston is sealed, and the liquid is sucked again. In this way, the liquid can be squeezed out.

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