Abstract: A reciprocating piston pump assembly comprises a cylinder housing with two internal chambers separated by a piston. The piston is coupled with a pushrod that reciprocates back and forth between two positions. The piston's position is tracked to measure the volume of fluid passing through the pump assembly. The pump assembly has two inlets, two outlets, two inlet passages, and two outlet passages. A first valve is positioned on the pushrod at a junction between the first inlet passage and first outlet passage. A second valve is positioned on the pushrod at a junction between the second inlet passage and second outlet passage. The pushrod can be positioned in a neutral position to simultaneously close both valves.

Abstract: A reciprocating piston pump assembly comprises a cylinder housing with two internal chambers separated by a piston. The piston is coupled with a pushrod that reciprocates back and forth between two positions. The piston's position is tracked to measure the volume of fluid passing through the pump assembly. The pump assembly has two inlets, two outlets, two inlet passages, and two outlet passages. A first valve is positioned on the pushrod at a junction between the first inlet passage and first outlet passage. A second valve is positioned on the pushrod at a junction between the second inlet passage and second outlet passage. The pushrod can be positioned in a neutral position to simultaneously close both valves.

Abstract: A reciprocating fluid meter assembly comprises a cylinder housing with two internal chambers separated by a piston. The piston is coupled with a pushrod that reciprocates back and forth between two positions. The piston's position is tracked to measure the volume of fluid passing through the meter. The meter has two inlets, two outlets, two inlet passages, and two outlet passages. A first valve is positioned on the pushrod at a junction between the first inlet passage and first outlet passage. A second valve is positioned on the pushrod at a junction between the second inlet passage and second outlet passage. The pushrod can be positioned in a neutral position to simultaneously close both valves. In some embodiments, the valves comprise a perforated spindle. The meter can also include a driving mechanism, such as an air cylinder or electric motor, for controlling the position of the pushrod.

Abstract: Apparatus, systems and methods in which an oscillating piston fluid meter assembly comprises a cylinder housing separated by a piston into two chambers and measures the flow volume of a fluid by tracking the distance traveled by the piston along a pushrod running through the cylinder. Preferably, the oscillating fluid meter assembly has two inlets, two outlets, two end-caps, and four passages each coupling one inlet or outlet to a chamber. A valve is positioned at a junction between two passages and can simultaneously control the two passages by shutting them both or allowing only one of them to be open. Magnets, springs, and various damping mechanisms are used to control the movement of the pushrod. Since fluid cannot pass through the system without triggering the traveling of the piston tracked by a tracking device, the oscillating fluid meter is highly sensitive and can detect a very small flow volume.