Emergency detachment mechanism for fluid handling device

1. An emergency detachment mechanism for a fluid handling device which is suitable for application in a fluid handling device that handles a very-low-temperature fluid, comprising:

a pair of couplers, each provided with a valve body for blocking circulation of a fluid during an emergency, are separably connected in a state of abutment by a connecting mechanism; during an emergency detachment, the connecting mechanism performs a disconnecting operation to disconnect the couplers from each other, the valve bodies provided to the couplers close due to the couplers being disconnected, and opening parts of the couplers close due to the couplers being disconnected, and the couplers are emergency-detached in a state in which fluid circulation is blocked and the fluid is prevented from flowing out to the exterior; the emergency detachment mechanism for a fluid handling device;

wherein each of the pair of couplers is composed of a coupler body part formed into a tubular shape through which a fluid circulates, the valve body that closes off the opening part of the coupler body part during emergency detachment, and a valve body drive mechanism for actuating the valve body; all constituent members of the valve body drive mechanism are provided inside the coupler body part and the valve body drive mechanism has an urging body that urges the valve body toward the opening part of the coupler body part; the valve body is urged toward the opening part of the coupler body part by urging force of the urging body of the valve body drive mechanism provided inside the coupler body part; when the couplers are connected to each other, the valve bodies are pushed against each other to retract against the urging force of the urging bodies, opening up the opening parts of the coupler body parts, and when the couplers are disconnected and separated from each other, the valve bodies are caused to protrude by the urging force of the urging bodies to engage by pressure contact with the opening parts of the coupler body parts and close off the opening parts of the coupler body parts; the coupler body parts are each formed from an internal tube part in which a fluid passes through an interior, an external tube part which is more enlarged in diameter at a distal end side than the internal tube part, and a connecting flange part that closes off a space between the internal tube part and the external tube part, a vacuum layer being formed between the internal tube part and the external tube part; the connecting flange part has a wall thickness less than a wall thickness of the external tube part, and is provided between distal ends of the internal tube part and the external tube part where a clearance between the internal tube part and the external tube part is greatest; and when the couplers are connected to each other, a heat-conducting part between the internal tube part and the external tube part is only the connecting flange part.

2. The emergency detachment mechanism for a fluid handling device according to claim 1 , wherein the valve bodies are each composed of a valve body base part and a valve body distal end part that covers a distal end side of the valve body base part and that is exposed to the atmosphere when the couplers are separated from each other, and the valve body distal end parts are made of a resin.

3. The emergency detachment mechanism for a fluid handling device according to claim 2 , wherein a peripheral edge of the opening part of each of the coupler body parts is provided with a valve seat that sections off the opening part, and the valve seat and the valve body base part that engages by pressure contact with the valve seat are both made of a metal.

4. The emergency detachment mechanism for a fluid handling device according to claim 3 , wherein engaging surfaces where each of the valve seats and valve body base parts engage with each other are formed into level differences, seals are provided to the level-difference parts of the valve seats or the valve body base parts, and the valve seats and the valve body base parts are engaged by the plurality of seals provided in multiple rows.