An improvement to an air operated double diaphragm pump may include ball guides to restrain movement of balls relative to suction and delivery seats to substantially linear travel, as opposed to the prior art three-dimensional travel. The guides may have curved surfaces to reduce wear on balls over prior art designs. The pumps may have supports and an intake manifold whereby the intake manifold may be removed to access the intake balls and intake ball valve seals without requiring the pump to be completely removed from an installation as is required with prior art designs.

Pumps are provided, more particularly piston type pumps having increased energy efficiency, systems incorporating such piston type pumps, and methods of operating piston type pumps. The pumps are suitable for pumping of oil from an oil well or for pumping other liquids such as ground water, subterranean liquids, brackish water, sea water, waste water, cooling water, gas, coolants, and the like.

Valve assemblies and related pumps and methods may include an insert disposed in an internal flow path of a casing where an outer surface of the insert is fixedly engaged with an inner surface the casing with fluid sealing. The insert includes protrusions, each individually extending into the internal flow path of the casing and converging at an apex of the insert to define a cage in which the restriction element is configured to move axially through the internal flow path.

A check valve assembly includes a housing having a fluid inlet arranged to be fluidly connected, in use, to a source of hydraulic fluid, a first stage body having a first stage fluid outlet and a second stage body having a second stage fluid outlet and a flow passage between the first and second stage bodies. The first stage body is a hollow body having a first end in fluid communication with the fluid inlet and housing a hollow first stage retainer around which is mounted a first stage spring that biases a first stage ball. The second stage body is a hollow body housing a second stage retainer around which is mounted a second stage spring that biases a second stage ball, and wherein a first stage pressure differential between the first stage fluid outlet and the fluid inlet creates a fluid flow path from the inlet outlet.

Valve assemblies and related pumps, plungers, lift assemblies, and methods may include an insert disposed in an internal flow path of a plunger. The insert includes protrusions, each individually extending into the internal flow path of the plunger and converging at an apex of the insert to define a cage in which the restriction element is configured to move axially through the internal flow path.