BUCHI Encapsulator B-395 Pro - Manual (Page 51)

6 Operation
51 B-395 Pro Operation Manual, Version C
7. Set the liquid flow rate and the vibration frequency to a value where a clear bead chain is obtained.
Activate the electrostatic dispersion unit at 300 V and increase the tension stepwise by 100 V until
the one-dimensional liquid jet is transformed into a funnel-like multi-line stream. The higher the
electrostatic charge the earlier the bead chain is separated. This prevents the beads from hitting
each other in flight, and from hitting each other as they enter the hardening solution. Therefore the
Encapsulator can routinely generate bead batches with homogeneity greater than 95 %. If nothing
happens, check that the electrode is connected to the control unit.
8. Change the vibration frequency and the flow rate and observe their influence on the electrostatic
tension needed to generate a jet separation. The use of electrostatic tension enlarges the working
range.
It can happen that after some time, the beads no longer enter, or actually jump out of the beaker.
This is due to the fact that electrostatic charges have accumulated in the electrically isolated
beaker. To avoid this phenomenon, place the supplied stainless steel clip of the grounding wire
over the edge of the beaker so it extends into the receiving liquid and connect the green-yellow
wire to the grounding plug on the front panel of the control unit. If you work with the complete
reaction vessel, then the electrostatic charges will be automatically eliminated without the need for
the grounding wire.
General Rule:
The larger the beads, the higher the electrostatic voltage needed to seperate the jet.
9. Change the amplitude of the vibration. You will observe only slight changes of the bead chain.
Very often values between 1 and 3 are optimal for low viscous solutions. If using immobilization
mixtures with rather high viscosity (> 150 mPa s), values higher than 3 might be more appropriate.
10. Repeat this procedure with another nozzle size.
General Rule:
• Smaller nozzles generate smaller bead sizes.
• The final bead diameter will be approximately 2 times the nozzle size.