A peristaltic pump comprising a pump housing, a compressible pump tube
positioned between rotatable occluding members and a pump tube track in
the housing, where there is an opening in the pump tube track between a
first occluding member and a second occluding member such that when the
second occluding member has exited occlusion of the pump tube at the
opening, a third occluding member completes occlusion of the pump tube
thus capturing a compensating volume of fluid between the first and third
occluding members, and when the second occluding member reenters
occlusion at the end of the opening, it displaces the compensating volume
towards the outlet of the pump tube, thus maintaining fluid velocity in
the outlet stream.