
Setting Up the XP3000 for Your Application
4-7
Another condition that affects breakoff is the formation of inertial air gaps. This is
seen as a small air gap inside the tubing at the tip. This occurs to a greater extent on
larger reagent syringes, and it enhances the breakoff of liquid from the tip of the
tubing. If an inertial air gap is not desired in the application, lowering the cutoff
velocity and/or the top velocity will remove the inertial air gap. However, this may
not give a clean breakoff of the fluid.
In some instances it may not be possible to improve fluid breakoff. Clean breakoff is
important to accuracy and precision; it is a concern especially when using slow
speeds because drops will usually adhere to the tip.
For example, using a 2.5 mL reagent syringe (P/N 5133, dispense tubing and
deionized water with a surfactant added):
* [S24IA3000OA0R] - will leave a drop on the tip
* [S24IA3000OA5S1A0R] - no drop will be left
* [V100IA3000OA0R] - will leave a drop on the tip
* [V100IA3000OA5V5500A0R] - no drop will be left
Increasing the cutoff velocity and ramp (slope) may also improve the fluid breakoff.
Smaller I.D. tubing may improve breakoff, especially for smaller syringes.
NOTE
It may not be possible to achieve good fluid breakoff under all
circumstances, especially with syringes smaller than 500 µL or with some
fluids.
11
Set backlash compensation.
The XP 3000 pump control includes backlash compensation during aspiration. The
backlash compensation causes the plunger to move down to the calculated stopping
point, then down an additional set number of steps. On reversing direction, the
plunger moves back up the same number of steps. Backlash compensation maintains
accuracy and precision in the syringe plunger movement when the plunger changes
direction.
Aspirate, then perform multiple dispenses. Compare the first aliquot to others; if low,
increase backlash and retest. Set backlash as low as possible, but keep the first
aliquot equal to subsequent aliquots.
Содержание XP 3000
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Страница 22: ...Hardware Setup 2 6 RS 485 CABLING Figure 2 4 RS 485 Multi Pump Cabling RS 485 A RS 485 B ...
Страница 23: ...Hardware Setup 2 7 CAN CABLING Figure 2 5 CAN Multi Pump Cabling ...
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