Irrigation valves for channels and for irrigation tanks are of three types. All are activated by a pair of tilting float arms to which a pair of floats are attached. One type is a T-shaped duct with a cylindrical valve disposed at 90 degrees to the part that is connected to the incoming flow. The floats rotate the valve. The second type has the same construction as the first type, thereby giving flow control but additionally has a rise and fall gate in the duct part that is connected to the incoming flow. The gate acts as a stop valve. The third type has a cylindrical duct connectable to the incoming flow but no valve and provides both flow control and stop valve facilities through a rise and fall gate actuated by the tilting of the float arms.

A negative pressure pipeline opening-and-closing device includes a blocking member and a buoyant member. The buoyant member comprises two floats and a connection rod connected to the two floats. The liquid reservoir is provided with a guide therein, and the guide confines the two floats, the blocking member and the liquid outlet port in the same vertical line. A limiting member is arranged between the two floats and is fixed to an inner wall of the liquid reservoir. A maximum distance between the limiting member and a top wall of a lower float of the two floats is smaller than a maximum distance between a top wall of an upper float of the two floats and a top wall of the liquid reservoir. The negative pressure pipeline opening-and-closing device can replace an existing electrically controlled valve. Therefore, the cost is reduced, the maintenance is convenient and service life is prolonged.

A negative pressure pipeline opening-and-closing device includes a blocking member and a buoyant member. The buoyant member comprises two floats and a connection rod connected to the two floats. The liquid reservoir is provided with a guide therein, and the guide confines the two floats, the blocking member and the liquid outlet port in the same vertical line. A limiting member is arranged between the two floats and is fixed to an inner wall of the liquid reservoir. A maximum distance between the limiting member and a top wall of a lower float of the two floats is smaller than a maximum distance between a top wall of an upper float of the two floats and a top wall of the liquid reservoir. The negative pressure pipeline opening-and-closing device can replace an existing electrically controlled valve. Therefore, the cost is reduced, the maintenance is convenient and service life is prolonged.

A valve assembly may be used with a container for holding a fluid including a liquid and a gas. The valve assembly may have a chamber, inlet, and outlet. The chamber may provide an exhaust route for fluid from the container to the outlet. A check valve including a sealing member with a through hole may move between an open and closed position. In the open position, check valve may provide a main flow route for fluid leaving the internal chamber. The through hole may provide a limited return flow route for gas returning to the internal chamber when the check valve is closed. The valve assembly may include a breather check valve movable between a closed and open position in which it provides fluid communication between the exhaust route and externally of the housing. A filter may communicate with the breather check valve.

In a valve device for a fuel tank, a fuel liquid level of filling-up fuel feed and an allowable fuel amount of additional fuel feed can be easily and appropriately changed by replacing only a part of components forming the valve device. A first valve chamber has a structure of positioning an open end below a support portion of a first float having a passage portion for a fluid. A second valve chamber includes a support portion of a second float having a passage portion for the fluid. The first valve chamber and the second valve chamber are formed by fitting a lower-portion including the support portion and the open end of the first float and the support portion of the second float relative to an upper-portion including a first valve opening and a second valve opening.

A negative pressure pipeline opening-and-closing device includes a blocking member and a buoyant member. The buoyant member comprises two floats and a connection rod connected to the two floats. The liquid reservoir is provided with a guide therein, and the guide confines the two floats, the blocking member and the liquid outlet port in the same vertical line. A limiting member is arranged between the two floats and is fixed to an inner wall of the liquid reservoir. A maximum distance between the limiting member and a top wall of a lower float of the two floats is smaller than a maximum distance between a top wall of an upper float of the two floats and a top wall of the liquid reservoir. The negative pressure pipeline opening-and-closing device can replace an existing electrically controlled valve. Therefore, the cost is reduced, the maintenance is convenient and service life is prolonged.

There is provided a liquid level control device (20) for location in a vessel to control the liquid level in the vessel. The liquid level control device (20) comprises: a first chamber (22) including: an opening (26) to allow movement of liquid between the first chamber (22) and the vessel; a vent (28) to allow egress of air from the first chamber (22); and an inlet (30) connectable to a liquid source (34); a first flow controller including a first float (36) arranged in the first chamber (22) such that the flow of liquid into the first chamber (22) raises the first float (36) and displaces air in the first chamber (22) via the vent (28), the first flow controller including a first closure member (40) movable to selectively close and open the inlet (30), the first float (36) further arranged in the first chamber (22) such that, in use, when the first float (36) is at a first position when the liquid level in the first chamber (22) is at or below a first predetermined level, the first float (36) positions the first closure member (40) to open the inlet (30) to allow liquid into the first chamber (22) via the inlet (30), and when the first float (36) is at a second position when the liquid level in the first chamber (22) is at or above a second predetermined level, the first float (36) positions the first closure member (40) to close the inlet (30) to block liquid from entering into the first chamber (22) via the inlet (30); and a second flow controller including a second float (42) and further including a second closure member (46) movable to selectively close and open the vent (28), the second float (42) arranged such that, in use, when the second float (42) is in a first position, the second float (42) positions the second closure member (46) to close the vent (28) to block air from flowing from the first chamber (22) via the vent (28) to escape to atmosphere, and when the second float (42) is in a second position, the second float (42) positions the second closure member (46) to open the vent (28) to allow air to flow from the first chamber (22) via the vent (28) to escape to atmosphere, wherein the first and second floats (42) are arranged such that, in use, when the first float (36) is in its second position and the second float (42) is in its first position, air is trapped in the first chamber

In a valve device for a fuel tank, a fuel liquid level of filling-up fuel feed and an allowable fuel amount of additional fuel feed can be easily and appropriately changed by replacing only a part of components forming the valve device. A first valve chamber has a structure of positioning an open end below a support portion of a first float having a passage portion for a fluid. A second valve chamber includes a support portion of a second float having a passage portion for the fluid. The first valve chamber and the second valve chamber are formed by fitting a lower-portion including the support portion and the open end of the first float and the support portion of the second float relative to an upper-portion including a first valve opening and a second valve opening.

A backflow valve assembly for preventing gas and backup waste from escaping a floor drain includes a tube that is configured to fluidically couple to a drain line. A pipe is coupled to and axially positioned in the tube. The pipe has upper and lower ends that are closed. At least one gasket is coupled to an inner surface of the pipe and defines upper and lower chambers. Penetrations are positioned through the pipe to allow flow of gasses and liquids into the pipe. First and second balls, which are less dense than water, are positioned in the upper and lower chambers, respectively. The first ball prevents escape of the gasses from the tube. The first ball floats to open the gasket to permit the flow of the liquids to the drain line. The second ball floats to close the gasket to prevent escape of waste from the tube.

An opening/closing device according to the present invention includes a gate, a fall prevention unit, a support release unit, a first float, a floating prevention unit, a second float, and a floating prevention release unit. The gate receives a flow of fluid, and is able to fall down toward a downstream direction of the flow. The fall prevention unit supports the gate, thereby preventing the gate from falling down. The support release unit releases the support for the gate by the fall prevention unit. The first float is arranged on an upstream side of the gate, is arranged on one of the left side and the right side of the gate viewed from upstream, and is less in the specific gravity than the fluid. The floating prevention unit prevents the first float from floating.