Valve assemblies for reciprocating downhole pumps are provided. The valve assembly may comprise: a flow cage comprising a housing and a tubular insert; an annular valve seat positioned below the tubular insert; and an elongated sealing member positioned above the annular valve seat and at least partially received into the tubular insert. In some embodiments, the elongated sealing member may be more stable and may more securely engage the valve seat compared to spherical valve balls. Related methods are also provided.

The subject of the present invention is a valve for extracting, by pumping, a fluid contained in a space, said valve comprising: a) a main body having a first opening for the passage of said fluid during pumping, and b) an indicator means configured to indicate whether or not the fluid is passing through the first opening.

A draining device for draining fuel from a fuel vapor system into a fuel tank is provided, the draining device comprising a port configured to be coupled to a fuel vapor accessory and a sealing member displaceable between a closed position in which the port is closed by the sealing member and an open position in which fuel from the fuel vapor accessory can be drained into the tank, wherein the sealing member is displaced into the open position when pressure in the tank is substantially equal to the atmospheric pressure and the fuel level in the tank is below the fuel level in the fuel vapor accessory.

Described is a check valve having a valve housing, a valve seat, a ball and a spherical loading element. The valve seat is disposed proximate to a first end of the bore. The ball is disposed in the bore and is movable between a closed position in which the ball is received against the valve seat and prevents a flow of fluid through the bore and an open position in which the ball is displaced from the valve seat and allows fluid to flow through the bore. The spherical loading element is disposed in the bore and is movable between the ball and the second end of the bore. The spherical loading element applies a supplemental force to move the ball against the valve seat during closing of the check valve. The check valve provides a low and predictable cracking pressure which does not vary significantly between similarly manufactured valves.

There is provided a powerless back-flow prevention apparatus comprising: a body having a sewage inlet at a front thereof, a sewage outlet at a rear thereof, and a length-wise sewage channel there between; a door pivotally coupled to the body at the rear thereof to open or close the outlet, wherein the door comprises: a number of floating members arranged spacedly with each other; and a guide disposed on the floating members to pivot upwards via the floating force to close the outlet, and to pivot downwards via a gravity in an absence of the sewage back-flow to open the outlet, and, then to guide the sewage from the outlet.

There is provided a powerless back-flow prevention apparatus comprising: a body having a sewage inlet at a front thereof, a sewage outlet at a rear thereof, and a length-wise sewage channel there between; a door pivotally coupled to the body at the rear thereof to open or close the outlet, wherein the door comprises: a number of floating members arranged spacedly with each other; and a guide disposed on the floating members to pivot upwards via the floating force to close the outlet, and to pivot downwards via a gravity in an absence of the sewage back-flow to open the outlet, and, then to guide the sewage from the outlet.