Watson-Marlow PF22 - Manual (Page 20)

Operators Manual
PF22
PF22 OM EN 74-132-005 v1.02.doc Version: 1.02 Page 20 of 34
6.2 Choice of tube
PF22 can operate with six different tube dimensions chosen according to the volume to be
dispensed.
The tubes are designated by their internal diameters (i.d.) in millimetres. This value is always used
as designation for the tube, and this is also the value to be entered in Function 2 of PF22.
PF22 can operate with the following tubes:
Tube dimension
Min. volume
recommended
3.0 mm i.d. 10 ml
5.0 mm i.d. 20 ml
6.5 mm i.d. 50 ml
8.0 mm i.d. 85 ml
10.0 mm i.d. 150 ml
12.5 mm i.d. 250 ml
In order to obtain consistent and good results, the choice of tube should be made according to the
above recommendations.
Example of tube choice:
The filling time for a volume of 10.0 ml with a Ø3.0 id. tube in a PF22 dispensing head is 1.1
seconds with dispenser running at speed of 250 rpm and 100 in acceleration.
The same volume can be obtained with Ø5.0 id. tube in 0.65 seconds with the same parameters.
The choice depends on the actual need. The Ø3.0 id. tube yields the better accuracy. The Ø5.0
i.d. yields the better capacity, since filling time is less.
Tubes must be cut in the right length in order to achieve optimised dispensing. It is
recommendable to keep the tubes as short as practically possible.
The tube ends must always be kept below the liquid level of the suction vessel in order to keep the
tubes from sucking air.
Avoid having tubes close to the bottom of product vessel.
The above is a guide only, and it will sometimes be necessary to make adjustments for the
individual applications.
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.
Priming is performed by pressing “PUMP” on the keypad.
Hold down “PUMP” for 1 second and the pump will start priming with 125 rpm.
Priming will continue as long as “PUMP” is held down.