Peristaltic pump with offset rollers having different sized diameters

A peristaltic pump assembly, comprising:

• a pump head, comprising:
• a first station, the first station including (1) a first tube portion configured to receive a first tube and/or a first tube connector section and (2) a second tube portion configured to receive a second tube and/or a second tube connector section;
• a second station, the second station including (1) a first tube portion configured to receive a first tube and/or a first tube connector section and (2) a second tube portion configured to receive a second tube and/or a second tube connector section;
• a first outer tube interface surface portion positioned to contact a first tube extending between the first station and the second station;
• a second outer tube interface surface portion positioned to contact a second tube extending between the first station and the second station;
• a motor having a drive shaft;
• and
• a rotor connectable to the drive shaft so as to be rotatable therewith, the rotor comprising:
• a first pair of roller assemblies and a second pair of roller assemblies, each of the first pair of roller assemblies including a first roller portion having a first diameter and a second roller portion having a second diameter, wherein the first diameter is larger than the second diameter, each of said first pair of roller assemblies comprising a first side edge and a second side edge on either side of the first roller portion and extending radially outward therefrom, each of said first pair of roller assemblies further comprising a third side edge and a fourth side edge on either side of the second roller portion and extending radially outward therefrom;
• and
• each of the second pair of roller assemblies including a first roller portion having a first diameter and a second roller portion having a second diameter, wherein the first diameter is smaller than the second diameter, each of said second pair of roller assemblies comprising a first side edge and a second side edge on either side of the first roller portion and extending radially outward therefrom, each of said second pair of roller assemblies further comprising a third side edge and a fourth side edge on either side of the second roller portion and extending radially outward therefrom;
• wherein the first pair of roller assemblies and the second pair of roller assemblies are positionable around a circumference of the rotor such that each one of the first pair of roller assemblies is positioned around the circumference of the rotor and is directly proceeded by one of the second pair of roller assemblies and is directly followed by the other of the second pair of roller assemblies, and the first roller portion of the first pair of roller assemblies is aligned with the first roller portion of the second pair of roller assemblies and the second roller portion of the first pair of roller assemblies is aligned with the second roller portion of the second pair of roller assemblies;
• wherein the first roller portion of the first pair of roller assemblies and the first roller portion of the second pair of roller assemblies are configured to selectively compress tubing against the first outer tube interface surface portion and the second roller portion of the first pair of roller assemblies and the second roller portion of the second pair of roller assemblies are configured to selectively compress tubing against the second outer tube interface surface portion.