A valve comprising: an inlet port, an outlet port, and a fluid conduit extending between the inlet port and the outlet port; a valve core comprising at least one flow restriction member (105, 109, 110) and a portion of the fluid conduit enveloping the at least one flow restriction member (105, 109, 110); the fluid conduit comprising an inlet conduit, the inlet conduit being interposed between the inlet port and the valve core and having a length dimension extending between the inlet port and the valve core; the fluid conduit comprising an outlet conduit, the outlet conduit being interposed between the valve core and the outlet port and having a length dimension extending between the valve core and the outlet port; the valve further comprising a valve body enveloping the inlet conduit; wherein the valve core comprises a throttle situated in the fluid conduit; wherein the throttle is movable between a closed position and an open position; wherein the throttle in the closed position closes the fluid conduit; wherein the throttle in the open position opens the fluid conduit; wherein the valve core comprises a displaceable member situated in the fluid conduit; wherein the displaceable member is moveable to increase a volume of the fluid conduit such that the displaceable member increases a flow rate through the fluid conduit, and to decrease the volume of the fluid conduit such that the displaceable member lowers the flow rate through the fluid conduit; the valve comprising a biasing member coupled to the displaceable member and configured to urge the displaceable member such that the biasing member urges the volume of the fluid conduit to increase, thereby increasing the flow rate through the fluid conduit; wherein the displaceable member faces the throttle; characterized in that the valve body has a first slot and has a second slot, the first and the second slot being in fluid communication with the inlet conduit, the first and the second slot being disposed on opposite sides of the inlet conduit; and in that the length dimension of the inlet conduit exceeds the length dimension of the outlet conduit by at least ten percent; and in that the valve comprises a first ultrasonic transducer disposed in the first slot and a second ultrasonic transducer disposed in the second slot; and in that the inlet conduit diameter is at least ten percent less than the inlet port diameter. an inlet port, an outlet port, and a fluid conduit extending between the inlet port and the outlet port; a valve core comprising at least one flow restriction member (105, 109, 110) and a portion of the fluid conduit enveloping the at least one flow restriction member (105, 109, 110); the fluid conduit comprising an inlet conduit, the inlet conduit being interposed between the inlet port and the valve core and having a length dimension extending between the inlet port and the valve core; the fluid conduit comprising an outlet conduit, the outlet conduit being interposed between the valve core and the outlet port and having a length dimension extending between the valve core and the outlet port; the valve further comprising a valve body enveloping the inlet conduit; wherein the valve core comprises a throttle situated in the fluid conduit; wherein the throttle is movable between a closed position and an open position; wherein the throttle in the closed position closes the fluid conduit; wherein the throttle in the open position opens the fluid conduit; wherein the valve core comprises a displaceable member situated in the fluid conduit; wherein the displaceable member is moveable to increase a volume of the fluid conduit such that the displaceable member increases a flow rate through the fluid conduit, and to decrease the volume of the fluid conduit such that the displaceable member lowers the flow rate through the fluid conduit; the valve comprising a biasing member coupled to the displaceable member and configured to urge the displaceable member such that the biasing member urges the volume of the fluid conduit to increase, thereby increasing the flow rate through the fluid conduit; wherein the displaceable member faces the throttle; characterized in that the valve body has a first slot and has a second slot, the first and the second slot being in fluid communication with the inlet conduit, the first and the second slot being disposed on opposite sides of the inlet conduit; and in that the length dimension of the inlet conduit exceeds the length dimension of the outlet conduit by at least ten percent; and in that the valve comprises a first ultrasonic transducer disposed in the first slot and a second ultrasonic transducer disposed in the second slot; and in that the inlet conduit diameter is at least ten percent less than the inlet port diameter.