Bredel Hose pump Series Manual page 18

DESCRIPTION
(C). A bearing-mounted rotor (D) with two facing
integral pressing shoes (E) is in the centre of the pump
head.
In phase 1 the lower shoe compresses the pump hose
by the rotational movement of the rotor, forcing the fluid
through the hose. As soon as the shoe has passed, the
hose recovers to its original shape due to the
mechanical properties of the material.
In phase 2 the product is drawn into the hose by the
(continuous) turning motion of the rotor.
In phase 3, the second integral pressing shoe will
subsequently compress the pump hose. Due to the
continuous rotating movement of the rotor not only new
product is sucked in, but also the already present
product is pressed out by the shoe. When the first shoe
runs from the pump hose, the second shoe has already
closed the pump hose and the product is prevented
from flowing back. This method of liquid displacement is
also known as the "positive displacement principle".
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