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The micro-pump runs but does not produce a droplet
a)
Make sure liquid system is filled as described in section 5.3.
b)
If pump runs but liquid does not appear at the dispensing tip, make sure the pump lid screw
(C in Figure D-2) is firmly tightened.
c)
If still no liquid is pumped, release stop screw (B in Figure D-2) ½ a turn and then tighten
the pump lid screw (C) firmly again.
d)
Repeat (c) above until liquid is pumped inside tubing (use pump position FILL).
The pendant droplet continues to build up after pump has stopped
The pump tubing must be completely shut after the pumping has stopped. If not, liquid will continue
to flow through the pump tubing. See Appendix D of this manual to adjust the pump function.
The droplet climbs up on the outside of the dispensing tip
The outside of the dispensing tip is wet or is not clean.
Dip a cotton swab in an evaporating solvent (e.g. alcohol) and wipe the tip clean on the outside.
Some liquids of very low surface tension (e.g. organic solvents) might still tend to wet the outside of
the dispensing tip due to the tip material. To reduce this it might be necessary to use PTFE tubing with
a large cross section and a small inner diameter (P/N 860315,
Ø
1.5x0.2 mm) without inserting a metal
needle at the tip.
Droplet forms nicely at the dispensing tip but does not release from the tip in Dynamic test mode
Increase the droplet size to overcome the adhesion between the liquid droplet and the
dispensing tip.
The Dynamic test gives no test result at all
The dynamic test is triggered by the drop application. Possible errors are:
a)
The image capturing might start “too early”.
If the pendant drop is too close to the surface it might trigger the image capturing before the
droplet is dropped. Increase the distance to the surface slightly.
b)
The Dynamic test might have “timed out”
After the test button has been pressed the scanning process will time out after 30 seconds.
Pump out a droplet before the program button is activated and apply the droplet during the 30-
second period.
Test results appear to be incorrect or “zero”
When a captured image cannot be evaluated automatically, the result is a line of zeroes.
The automatic analysis will fail if the captured image is of poor quality because of incorrect settings.
Some examples could be a droplet contour that is broken, the droplet base is hidden in the background
or the image is too bright and the droplet cannot be detected.
The captured image is still available and can be displayed if the incorrect result line is double-clicked
(see Section 9.5 Manual testing in Static/Dynamic Mode)
