A fluid delivery apparatus includes controller hardware, a diaphragm pump, a positive displacement pump, and a fluid conduit extending between the diaphragm pump and the positive displacement pump. During operation, and delivering fluid to a downstream recipient, the controller hardware draws fluid into a chamber of the diaphragm pump from a fluid source container. The controller hardware applies pressure to the chamber of the diaphragm pump to output the fluid in the chamber of the diaphragm pump downstream through the fluid conduit to the positive displacement pump. During application of the pressure to the chamber and outputting the fluid in the chamber of the diaphragm pump downstream, the controller hardware activates the positive displacement pump to pump the fluid from the positive displacement pump to the downstream recipient.

A reciprocating fluid pump may include a pump body, one or more subject fluid chambers within the pump body, one or more drive fluid chambers within the pump body, and a shuttle valve for shifting flow of pressurized drive fluid between two or more conduits. The shuttle valve includes a valve body and a spool disposed within the valve body and configured to move between a first position and a second position within the valve body. The shuttle valve also includes one or more magnets carried by the spool. The magnets are located and configured to impart a force on the spool responsive to a magnetic field such that the spool is magnetically biased away from an intermediate position between the first position and the second position.

A reciprocating fluid pump may include a pump body, one or more subject fluid chambers within the pump body, one or more drive fluid chambers within the pump body, and a shuttle valve for shifting flow of pressurized drive fluid between two or more conduits. The shuttle valve includes a valve body and a spool disposed within the valve body and configured to move between a first position and a second position within the valve body. The shuttle valve also includes one or more magnets carried by the spool. The magnets are located and configured to impart a force on the spool responsive to a magnetic field such that the spool is magnetically biased away from an intermediate position between the first position and the second position.

A pump housing includes an integral vent flow path extending between a low-pressure region and the reservoir. The vent path provides fluid communication between the downstream side of a throat seal dividing the low-pressure region from a high-pressure region and the reservoir. Lubricant flows through the vent path from the reservoir to the low-pressure region to provide lubrication to the throat seal.

A pump housing includes an integral vent flow path extending between a low-pressure region and the reservoir. The vent path provides fluid communication between the downstream side of a throat seal dividing the low-pressure region from a high-pressure region and the reservoir. Lubricant flows through the vent path from the reservoir to the low-pressure region to provide lubrication to the throat seal.

A fluid delivery apparatus includes controller hardware, a diaphragm pump, a positive displacement pump, and a fluid conduit extending between the diaphragm pump and the positive displacement pump. During operation, and delivering fluid to a downstream recipient, the controller hardware draws fluid into a chamber of the diaphragm pump from a fluid source container. The controller hardware applies pressure to the chamber of the diaphragm pump to output the fluid in the chamber of the diaphragm pump downstream through the fluid conduit to the positive displacement pump. During application of the pressure to the chamber and outputting the fluid in the chamber of the diaphragm pump downstream, the controller hardware activates the positive displacement pump to pump the fluid from the positive displacement pump to the downstream recipient.