Displacement Pump

A pump comprising:

• a variable volume compartment defined between a chamber-forming body and a movable member movable relative to the chamber-forming body wherein movement of the movable member changes a volume of the variable volume compartment between a first volume and a second volume different than the first volume,
• a tubular valve casing elongate along a casing axis and defining a valve chamber therein,
• the valve chamber having an inner wall circular in cross-section along the axis, an inlet end and an outlet end,
• a valve member coaxially located within the valve chamber,
• the valve member comprising a stem extending axially within the valve chamber,
• an inlet disc extending radially outwardly from the stem to a distal end in engagement with wall, the inlet disc engaging the wall to prevent fluid flow axially therepast in a direction from the outlet end towards the inlet end, the inlet disc being resiliently deflectable to be deflected from engaging the wall to permit fluid flow axially therepast in a direction from the inlet end towards the outlet end,
• an outlet disc extending radially outwardly from the stem to a distal end in engagement with wall, the outlet disc engaging the wall to prevent fluid flow axially therepast in a direction from the outlet end towards the inlet end, the outlet disc being resiliently deflectable to be deflected from engaging the wall to permit fluid flow axially therepast in a direction from the inlet end towards the outlet end,
• the inlet disc spaced axially away from the outlet end from the outlet disc,
• the outlet disc spaced axially away from the inlet end from the inlet disc,
• an inlet into the valve chamber spaced axially away from the outlet end from the inlet disc,
• an outlet from the valve chamber spaced axially away from the inlet end from the outlet disc the outlet disc,
• a fluid transfer port in communication with the variable volume compartment and open into the valve chamber in between the inlet disc and the outlet disc.