输液器 / Infusion Apparatus

Open the hook switch in the bottom of the infusion bottle to let air in.
The cone gets close to the bottle gradually with the drawdown of liquid level.
The blue hook mouth is close to bottom to make the bottle airtight when used to guarantee the security of liquid inside.
A rabbet connected with the bottom is designed on the hook mouth to ensure it won’t drop even when the hook mouth is open.
The cone will plug up the hole when reaching the bottom. The alarm will go off from the cone because of the same structure of the whistle when the air is through.