A liquid pumping apparatus for pumping liquids, more specifically a linear
peristaltic pump apparatus. The apparatus consists of a high durometer compressible elastomeric liquid flow tube (12), an infeed valve
assembly (26), an outfeed valve
assembly (38), an extensible and retractable
actuator anvil (34) having a round surface which engages the flow tube (12) at all times, an opposed anvil (24.1) having a round surface in engagement with the flow tube at all times, the flow tube being held between the anvils (34, 24.1) in a slightly compressed state when the anvil (34) is retracted, and a control
assembly (100) for causing the movable anvil to be sequentially extended and retracted to cause flow within the flow tube (12) from the infeed valve assembly (26) to the outfeed valve assembly (38). With this apparatus the lumen of the flow tube (12) to the sides of the anvils is not completely reduced to zero volume during displacement compression whereby gas embolisms do not erupt or explode when discharged. Two principal embodiments are disclosed, one having infeed and outfeed check valves which oclude the flow tube, and the other having check valves.