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.

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.

A water hammer-proof air valve that has a valve body and a bonnet, that are fixedly connected, a valve opening is provided on the valve body, and a high-speed intake and exhaust device is provided in an inner cavity of the valve body. A bonnet opening is provided on the bonnet, an output end of the high-speed intake and exhaust device penetrates the bonnet opening and is communicated with a high-speed exhaust throttling device for limiting an exhaust amount of gas of the high-speed intake and exhaust device, an output end of the high-speed exhaust throttling device is communicated with an outside air, and a trace exhaust device for discharging the gas separated out from the pipeline to the outside through the high-speed exhaust throttling device after the high-speed intake and exhaust device closes the valve is further provided in the high-speed intake and exhaust device.

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 shut-off valve system includes a tank having an inlet and an outlet with a flow path defined therebetween. A float within the tank occludes the tank outlet at a first fluid level under positive G forces and unoccludes the tank outlet at a second fluid level under positive G forces. A flow restricting orifice and/or a hydraulic fuse is downstream of float and tank outlet to restrict fluid communication between tank outlet and an ejector pump. A method for restricting flow in an ecology fuel return system includes recovering fuel from engine components, communicating the fuel to an inlet of a fuel tank, pumping the fuel from an outlet of fuel tank to an inlet of an engine when a float within tank unoccludes the outlet of the fuel tank, and restricting fluid flow from tank outlet to an ejector pump with a flow restricting orifice and/or a hydraulic fuse.

A shut-off valve includes a float and a negative G control component. The float is configured to occlude a tank outlet at a first fluid level and 1 G and unocclude the tank outlet at a second fluid level and 1 G. The negative G control component is operatively connected to the float to limit fluid, e.g. liquid or gas, communication between a tank outlet and an ejector pump during negative G events. An ecology fuel return system includes a tank, an ejector pump, a float, and a negative G control component, as described above. The tank has an inlet and an outlet. The inlet is configured to be in fluid communication with components of an engine. The ejector pump is in fluid communication with the tank outlet and is configured to pump fuel from the tank to a fuel pump inlet of an engine.

A shut-off valve includes a float and a negative G control component. The float is configured to occlude a tank outlet at a first fluid level and 1 G and unocclude the tank outlet at a second fluid level and 1 G. The negative G control component is operatively connected to the float to limit fluid, e.g. liquid or gas, communication between a tank outlet and an ejector pump during negative G events. An ecology fuel return system includes a tank, an ejector pump, a float, and a negative G control component, as described above. The tank has an inlet and an outlet. The inlet is configured to be in fluid communication with components of an engine. The ejector pump is in fluid communication with the tank outlet and is configured to pump fuel from the tank to a fuel pump inlet of an engine.

A water hammer-proof air valve that has a valve body and a bonnet, that are fixedly connected, a valve opening is provided on the valve body, and a high-speed intake and exhaust device is provided in an inner cavity of the valve body. A bonnet opening is provided on the bonnet, an output end of the high-speed intake and exhaust device penetrates the bonnet opening and is communicated with a high-speed exhaust throttling device for limiting an exhaust amount of gas of the high-speed intake and exhaust device, an output end of the high-speed exhaust throttling device is communicated with an outside air, and a trace exhaust device for discharging the gas separated out from the pipeline to the outside through the high-speed exhaust throttling device after the high-speed intake and exhaust device closes the valve is further provided in the high-speed intake and exhaust device.