Tank-locking device, system for managing liquid supply and method using the same

A tank-locking device, suitable for a liquid tank having an eye ring, comprising:

• a body;
• a fastening portion, connected to a side of the body for fastening the tank-locking device onto the liquid tank;
• a vessel body, embedded in the body, wherein a liquid inlet of the vessel body is protruded from the body;
• a piston, disposed in the vessel body;
• a driving rod, slideably disposed in the vessel body, wherein an end of the driving rod is connected to the piston;
• and
• a locking detent, connected to another end of the driving rod and having a cavity portion;
• wherein when the piston is exerted by a liquid pressure from the liquid inlet of the vessel body, the piston drives the driving rod to move the locking detent along a moving axis from a release position to a locking position so as to make the cavity portion snap the eye ring.