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5 Operation BÜCHI Mini Spray Dryer B-191
5.2 Spray process
1. Turn apparatus on using the main switch and open the
main compressed-air cock. The apparatus now carries
out an automatic self check and then goes automatically
into operating mode.
2. If the apparatus is provided with pneumatic nozzle cleaner
than the pressure in the manometer of the control unit
must display 4.5 bar. If this is not the case this must be
readjusted with the adjustment knob on the control unit.
3. Set air flow at about 600 l/h with the adjustment knob.
4. Preselect the desired input temperature with the adjust-
ment button.
5. Turn on the aspirator and set output with the adjustment
button. This output selection is an empirical value which
differs from product to product and can not be given.
6. Turn on heating and allow the system to warm-up. The
system regulates the input temperature itself. The LED in
the heating adjustment button only goes out when the
system temperature has stabilized. The LED is not a heat-
ing interval display.
7. If necessary, the nozzle cooling water and, if present, the
nozzle cleaner, are now turned on.
8. Distilled water is now slowly sprayed in by means of the
peristalsis pump. The spray cone now produced should
be located in the middle of the spray cylinder. If this is not
the case the nozzle may be dirty or defective.
9. The spray quantity of distilled water can be changed with
the adjustment button of the peristalsis pump. The spray
quantity in turn has an influence on the output temperature,
since the water draws energy from the air by evaporation.
In this way the output temperature can be set to the desired
value with the quantity of sprayed water and pump speed
of the peristalsis pump. Care is to be taken that the product
is not destroyed by a too high output temperature.
10. As soon as the desired operating conditions have been
achieved and are stable, the distilled water which is sprayed
in is replaced by the prepared product. Somewhat less
water is now sprayed into the system by the concentration
of the product in the water, which results in renewed ad-
justment of the output temperature (the pump output can
be slightly increased).
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