The peristaltic pump is like squeezing a flexible pipe filled with fluid
with a finger, and moving the fluid forward along the sliding pipe with
the finger. Peristaltic pumps are also based on the principle that the
wheel replaces the finger. The fluid is pumped by alternating extrusion
and release of the flexible conveying hose of the pump. Like squeezing a
hose with two fingers, as the fingers move, a negative pressure is
formed in the hose and the liquid flows along with it.
Peristaltic pump is a kind of "pillow" fluid formed in a section of pump
pipe between two rollers. The volume of the "pillow" depends on the
inner diameter of the pump pipe and the geometric characteristics of the
rotor. The flow rate depends on the product of the rotational speed of
the pump head and the size of the "pillow" and the number of "pillows"
produced by the rotor in each turn. The size of "pillow" is usually
constant (except when pumping fluid with extra viscous fluid).
Comparing the pumps with the same diameter of the rotor, the pumps with
larger "pillow" volume are produced, and the volume of fluid transported
by the rotor in each turn is larger, but the pulsation degree is also
larger. This is similar to the case of diaphragm valves. A pump with a
smaller "pillow" volume is produced, and the fluid volume conveyed by
the rotor is smaller in each turn; moreover, the small "pillow" formed
rapidly and continuously makes the fluid flow more stable. This is
similar to the working mode of gear pump.