Patent ID: 8096785

Claim:
A hydraulically driven multicylinder diaphragm pumping machine, the pumping machine comprising a plurality of pump cylinders ( 10 . 1 - 10 . 12 ) each having a first end ( 20 ) with a first inlet and outlet ( 21 ) for fluid to be pumped and a second end ( 30 ) with a second inlet and outlet ( 31 , 32 ) for hydraulic fluid, the inlets and outlets being associated with respective valves ( 23 , 24 ; 33 , 34 ), a separator ( 40 ) located inside and movable to-and-fro along the pump cylinder ( 10 ), the movable separator ( 40 ) having a first side ( 40 a ) facing the first end ( 20 ) of the cylinder and a second side ( 40 b ) facing the second end ( 30 ) of the cylinder, wherein: the movable separator ( 40 ) is connected to the inside ( 12 ) of the first end ( 20 ) of the cylinder by a first flexible diaphragm ( 45 ) in the form of a bellows that is expandable and contractable in concertina-like manner inside the cylinder ( 10 ) along the length direction of the cylinder as the movable separator ( 40 ) moves to-and-fro along the cylinder, the first side ( 40 a ) of the movable separator delimiting a first pumping chamber ( 47 ) inside the expandable and contractable flexible diaphragm ( 45 ) for containing a variable volume of pumped, fluid material in communication with the first inlet and outlet ( 21 ) in said first end ( 20 ) of the cylinder, said first inlet and outlet ( 21 ) communicating with said first chamber ( 47 ) whereby in operation fluid material to be pumped enters said first pumping chamber ( 47 ) via the first inlet and pumped fluid material leaves said first pumping chamber ( 47 ) via the first outlet; the movable separator ( 40 ) is connected to the inside ( 14 ) of the second end ( 30 ) of the cylinder by a second flexible diaphragm ( 46 ) in the form of a bellows that is contractable and expandable in concertina-like manner along the length direction of the cylinder ( 10 ) in correspondence with expansion and contraction of the first flexible diaphragm ( 45 ), the second side ( 40 b ) of the movable separator delimiting a second pumping chamber ( 48 ) inside the second expandable and contractable diaphragm ( 46 ) for containing a variable volume of a pumping hydraulic fluid in communication with the second inlet and outlet ( 31 / 32 ) in said second end ( 30 ) of the cylinder, said second inlet and outlet ( 31 , 32 ) communicating with said second pumping chamber ( 48 ) whereby in operation pumping hydraulic fluid enters said second pumping chamber ( 48 ) via the second inlet ( 31 ) and leaves said second pumping chamber ( 48 ) via the second outlet ( 32 ); and a closed annular non-pumping space ( 49 ) is defined between the outside of the first and second diaphragms ( 45 , 46 ) and the inner wall of the pump cylinder ( 10 ), which annular non-pumping space ( 49 ) in use contains a non-pumping fluid that is the same as said pumping hydraulic fluid or is different to said pumping hydraulic fluid but has equivalent hydraulic characteristics.