Provided are a check valve which can be easily mounted, a check valve structure which includes the check valve, and a hydraulic system which has the check valve structure. A check valve structure includes a partition wall for defining a first hole including a part of a hydraulic passage, and also includes a check valve inserted in the first hole, wherein the check valve structure is provided with: a base body having a base section which closes an open end of the first hole, and having a tubular section which has one end connected to the base section; and a sphere capable of making contact with the other end of the tubular section. The tubular section has formed therein a first through-hole communicating with a second hole connected to the first hole.

A gas safety valve for controlling a gas flow includes a valve body providing a body inlet port for coupling to a first gas supply and a body outlet port for coupling to an appliance, the valve body extending along a longitudinal axis between the body inlet port and the body outlet port, the valve body further providing an inlet bore extending downstream from the body inlet port, and an outlet bore extending to the body outlet port. A valve has a valve chamber having a valve inlet and a valve outlet, a ball located within the valve chamber and a valve seat provided at the valve outlet such that the ball is retained in the valve chamber upstream of the valve seat. The valve body includes an internal junction positioned upstream of the valve inlet, and a side inlet port.

A gas safety valve for controlling a gas flow includes a valve body providing a body inlet port for coupling to a first gas supply and a body outlet port for coupling to an appliance, the valve body extending along a longitudinal axis between the body inlet port and the body outlet port, the valve body further providing an inlet bore extending downstream from the body inlet port, and an outlet bore extending to the body outlet port. A valve has a valve chamber having a valve inlet and a valve outlet, a ball located within the valve chamber and a valve seat provided at the valve outlet such that the ball is retained in the valve chamber upstream of the valve seat. The valve body includes an internal junction positioned upstream of the valve inlet, and a side inlet port.

Provided is a ball check valve apparatus including: a first body into which wastewater is introduced; a second body coupled to the first body to be communicated with the first body and configured to discharge the wastewater introduced into the first body; and a valve member disposed in the first body such that the valve member is movable up and down in the first body and configured to close an opening/closing hole formed in the first body by a self-weight thereof and open the opening/closing hole by a pressure of wastewater introduced through the opening/closing hole.

Provided is a ball check valve apparatus including: a first body into which wastewater is introduced; a second body coupled to the first body to be communicated with the first body and configured to discharge the wastewater introduced into the first body; and a valve member disposed in the first body such that the valve member is movable up and down in the first body and configured to close an opening/closing hole formed in the first body by a self-weight thereof and open the opening/closing hole by a pressure of wastewater introduced through the opening/closing hole.

A Y-tool is configured for use with a pumping system that includes an electric submersible pump and bypass tubing. The Y-tool includes a slave valve assembly that controls access to the bypass tubing. The Y-tool also includes a master valve assembly driven by pressure from the electric submersible pump and a linkage assembly connected between the master valve assembly and the slave valve assembly.

A shoe in form of a slipper or sandal, includes a body 100 adapted to have a first fluid casing 12 and a second fluid casing 14, each having an elastic property, embedded in the front and rear portions of the body, respectively, and an instep strap 120 supported to the body in such a way as to be rotated in a specific section. A rotating shaft 16 is rotated in conjunction with the instep strap, and it includes a first connecting portion connected to the first fluid casing and a second connecting portion connected to the second fluid casing and an internal passage having respective check ball seating portions formed on the inside of the first and the second connecting portions, and with check ball received in the internal passage. When the rotating shaft is inclined by rotation of the rotating shaft, the check ball closely adheres to any one of the check ball seating portions by gravity or buoyancy and regulates a fluid flow to any one of the first and the second connecting portions.

A shoe in form of a slipper or sandal, includes a body 100 adapted to have a first fluid casing 12 and a second fluid casing 14, each having an elastic property, embedded in the front and rear portions of the body, respectively, and an instep strap 120 supported to the body in such a way as to be rotated in a specific section. A rotating shaft 16 is rotated in conjunction with the instep strap, and it includes a first connecting portion connected to the first fluid casing and a second connecting portion connected to the second fluid casing and an internal passage having respective check ball seating portions formed on the inside of the first and the second connecting portions, and with check ball received in the internal passage. When the rotating shaft is inclined by rotation of the rotating shaft, the check ball closely adheres to any one of the check ball seating portions by gravity or buoyancy and regulates a fluid flow to any one of the first and the second connecting portions.

An apparatus to allow or stop a flow into an enclosed environment or piping system comprises: (a) a housing having an upper flow passage, a middle flow passage, a lower flow passage; (b) a first valve seat, wherein the first valve seat is between the upper flow passage and the middle flow passage, and wherein a first opening is formed on the first valve seat; (c) a first rotary valve inside the housing, moving inside the upper flow passage and above the first valve seat; (d) a second valve seat, wherein the second valve seat is between the middle flow passage and the lower flow passage, wherein a second opening is formed on the second valve seat; and (e) a second rotary valve inside the housing, moving inside the middle flow passage and above the second valve seat.

An apparatus to allow or stop a flow into a piping system or an enclosed environment comprises a housing having an upper flow passage, a gasket, and a lower flow passage, wherein said gasket is between said upper flow passage and said lower flow passage, wherein said gasket has an inner diameter less than an inner diameter of said upper flow passage; a rotary valve inside said housing, wherein said rotary valve further comprises a main body and two guides affixed to said main body in opposition to each other, wherein said main body of said rotary valve is configured to be between said inner diameter of said gasket and said inner diameter of said upper flow passage, and wherein said rotary valve can move inside said upper flow passage and above said gasket; and two guide rails inside the upper flow passage.