INSTRUCTION HANDBOOK
PD22I / PD22P
PD22IP IH EN 74-125-102 v1.04
Page 12 of 20
6.3
Nature of fill media
The peristaltic dispensers are not suitable for viscous products. For viscous product another
type of dispenser from WM Flexicon can be used. In the case that the PD22 should be used
and the product is of viscous nature, then heating the product before dispensing with PD22 is
recommended.
Another consideration is the surface tension of liquid. Product with high surface tension tends
to produce drip. Due to this fact it is difficult to have sufficient cut off after every individual
dispense. When filling with small volumes and high surface tension present drips are often
produced and constitute inaccuracy.
6.4
Priming tubes
In order to evacuate air from the tubes and prepare the tubes for filling, it is necessary to
prime the tubes. Priming must be done adequately and continued until the tube material
hysteresis disappears as well as any air bubbles.
6.5
Drip
When dispensing very small volumes, the last drop of the filling constitutes a big part of the
total filling.
For small volumes a dumping nozzle system can be applied to control the last drop of filling.
When dispensing with very large volumes, the shape of nozzle and the filling speed required
may not always be compatible.
For this reason consideration should be done if using non-return valve or forced back-suction
is necessary.
Flexicon dispensers offer back-suction (reversing) after every individual dispensing.
6.6
Hard Feed
When dispensing with small tubes, counter pressure on the pressure side of pump head
might constitute inaccuracy and instability in filling (hard feed). In some cases the problem
can be resolved by using a larger tube on the pressure side (after Y-connector).
