Dual active valve fluid pressure operated positive displacement pump

A positive displacement pump comprising:

• a housing having at least three fluid ports, at least one inlet port configured to allow flow of a pumped fluid into the pump, at least one outlet port configured to allow flow of said pumped fluid out of the pump, and at least one driver pressure port configured to allow operating pressure into and out of the pump;
• at least one main piston movable within a space defined by at least one first interior wall of the housing between a first stable position and a second stable position under said operating pressure, said operating pressure acting in a space between the main piston and at least one second interior wall of the housing;
• at least one cavity coupled to or formed inside the main piston, said cavity divided into a first volume and a second volume by a freely moving divider;
• at least one first valve, operable by motion of said main piston, configured to provide fluid connection between said at least one inlet port and said first volume when the main piston in said first stable position;
• and
• at least one second valve, operable by the motion of said main piston, configured to provide fluid connection between said at least one outlet port and said first volume when the main piston in said second stable position;
• wherein said pump is operable by a single pressure, said operating pressure, pumping of fluid between the inlet port and the outlet port being controlled by said operating pressure, and fluid pressure at said inlet port and said outlet port determinable from measurement of said operating pressure.

A method of operating a positive displacement pump comprising steps of:

• providing a positive displacement pump comprising:
• a housing having at least two pumping ports for flowing a pumpable fluid into and out of the pump and at least one control port for flowing operating pressure into and out of the pump;
• at least one control port for flowing operating pressure into and out of the pump, connected to a pressure sensor;
• at least one cavity inside the housing, divided into a first volume and a second volume by a diaphragm, said first volume fluidly isolated from said second volume, said second volume fluidly connectable to said at least two pumping ports, said first volume fluidly connected to said at least one control port;
• said diaphragm movable by means of said operating pressure;
• said second volume reversibly enlargeable by movement of said diaphragm;
• and
• at least two actively controlled valves configured to control flow through said at least two pumping ports, fluid flow through all said at least two pumping ports controllable by at least one of said at least two valves, a first at least one of said at least two valves in fluid connection with a first at least one of said at least two pumping ports, a second at least one of said at least two valves in fluid connection with a second at least one of said at least two pumping ports, controlling of at least one of said at least two valves being independent of controlling of at least one other of said at least two valves;
• connecting at least one of said at least two pumping ports to a source of fluid;
• and
• executing at least one pump stroke, said pump stroke comprising:
• opening said first at least one of said at least two actively controlled valves and closing said second at least one of said at least two valves and decreasing said operating pressure, thereby enlarging said second volume and flowing said pumpable fluid into said second volume;
• and
• at such time as said second volume is fully enlarged, closing said first at least one of said at least two actively controlled valves and opening said second at least one of said at least two valves and increasing said operating pressure, thereby reversing enlargement of said second volume and flowing said pumpable fluid out of said pump
• wherein said diaphragm is a flexible plastic film, with a thickness in a range of 0.01 mm-0.5 mm, configured to freely move up and down in said at least one cavity leading to a movement of said diaphragm between a top of said at least one cavity and a bottom of said at least one cavity, during the pumping process, such that the same pressure is maintained in both volumes within said at least one cavity, thereby allowing a port pressure at at least two of said at least two pumping ports being determinable from measurement of said operating pressure received from the pressure sensor.