Abstract: A liquid tank connector for preventing leakage of contents in a liquid tank when removing a socket from a plug fixed to the liquid tank is provided. The liquid tank connector which includes a plug to be fixed to a liquid tank where liquid is stored, a socket which is able to be connected and disconnected with respect to the plug, and a sleeve for releasing a connected state between the plug and the socket by a relative movement with respect to the socket, and in which a liquid flow channels and gas flow channels are formed in a liquid deliverable state in which the plug and the socket are connected, and which includes: a cock which forms a gas flow channel in the liquid deliverable state, and the relative movement of the sleeve is controlled by the position of the cock in the liquid deliverable state.

Abstract: A plug structure is provided that can be installed on a container in which the thread of a container inlet for installing a cap is an outer thread, and furthermore, bubbles are not produced at the fluid surface inside the container even during fluid circulation. In a plug structure that is used in a container in which the thread of the container inlet for attaching the cap is an external thread, that is installed on the container inlet, that is capable of removing a fluid inside the container by using the siphon hose method, and that is capable of circulating the fluid that is inside the container, a fluid circulation path is provided that causes a fluid that is returning into the container during fluid circulation to fall along an external wall of a siphon hose during fluid removal.

Abstract: A fluid tank connector enables reliable separation of a plug and a socket by opposing the coupling force of a fluid sealing portion. The fluid tank connector is provided with a plug that is fit with play in the inner periphery of a fluid port of the fluid tank that stores a fluid, and a socket that is detachably connectable to the plug. The socket includes a sleeve that connects and disconnects the socket and the plug by being threadable on an external thread that is formed on the outer periphery of the fluid port. A pressing means is provided in the socket, and the pressing means applies a pressing force that separates the plug from the socket by opposing the coupling force of an 0-ring that seals the fluid path between the plug and the socket.