Abstract: A sealing structure includes a first connector body having a groove, a second connector body encompassing the first connector body, an O-ring partially received in the groove of the first connector body, and a variable back-up ring partially received in the groove of the first connector body and holding the O-ring. The variable back-up ring is deformable in a radial direction depending on a magnitude of a fluid pressure applied between the first connector body and the second connector body.

Abstract: An embodiment gas leak detection device includes a tip head part having a spherical shape, a tip connection part configured to communicate with the tip head part and connectable to a hydrogen detection line, a reference detection hole disposed at an end of the tip head part based on a longitudinal direction of the tip connection part, and a peripheral detection hole disposed in the tip head part, spaced apart from the reference detection hole, and directed in a direction intersecting the reference detection hole.

Abstract: A sealing structure includes a first connector body having a groove, a second connector body encompassing the first connector body, an O-ring partially received in the groove of the first connector body, and a variable back-up ring partially received in the groove of the first connector body and holding the O-ring. The variable back-up ring is deformable in a radial direction depending on a magnitude of a fluid pressure applied between the first connector body and the second connector body.

Abstract: A variable back-up ring includes: a first half shell; a second half shell having a symmetrical shape to the first half shell; and an inner cavity defined by the first half shell and the second half shell. The first half shell and the second half shell are deformable depending on a magnitude of a fluid pressure acting on the first half shell and the second half shell.

Abstract: A hydrogen supply apparatus is provided. The apparatus includes a first connecting member having a first flow path through which hydrogen is supplied and a second connecting member connected to the first connecting member and having a second flow path that communicates with the first flow path. A back-up ring has a first packing portion abutting an inner surface of the first connecting member, a second packing portion abutting an outer surface of the second connecting member, and a connecting portion connecting ends of the first packing portion and the second packing portion. An elastic member is elastically compressible and expandable between the first and second packing portions.