BUCHI Inert Loop B-295 - Manual (Page 50)

6 Operation
50 B-290 Operation Manual, Version I
6 .2 .3 Aspirator
The aspirator has a maximum gas flow rate
of approx. 35 m
3 /h. The flow depends on the
pressure drop of the overall system.
To determine the exact volume flow for steady
and re pro du cible operating conditions, a
measurement tube is supplied as an acces-
sory. A handheld gas flow meter (hot-wire flow
meter) is required for the mea surement.
Fig. 6.4: Aspirator settings versus throughput
6 .3 Spray process
During the spray process some parts i .e . all glassparts can get hot according to the
temperature settings of the instrument!
! Caution
Risk of minor or moderate burnings when handling hot parts.
• Do not touch hot parts
• Let the system cool down for some minutes after use
To carry out the spray process, proceed as follows:
1. Switch on the instrument. The instrument carries out an auto matic self check and then switches
automatically to the operating mode.
2. Set the air flow to about 40 mm with the rotary valve.
3. Pre-select the desired inlet temperature with the push-button.
4. Turn on the aspirator. As a standard, the aspirator rate should be 100 % to maximize the sepa-
ration rate of the cyclone. If a small powder humidity is required, the aspirator rate can be
decreased.
5. Turn on the heating and wait until the system has reached steady conditions.
6. If necessary, turn on the nozzle cooling.
7. Switch on the peristaltic pump. Pure solvent, e.g. distilled water in case of aqueous solutions,
is now sprayed in. The spray cone is symmetrical and located in the axis of the spray cylinder. If
this is not the case, the nozzle may be dirty or defective.
8. Set the automatic nozzle cleaning in case of clogging substance.
9. The spray quantity of pure solvent can be changed by means of the push-button of the peristaltic
pump. The spray flow strongly influences the outlet temperature, since the water draws energy
from the air by evaporation. Thus the outlet temperature can be set to the desired value by
means of the quantity of sprayed solution via the pump speed of the peristaltic pump.
The outlet temperature can be regarded as the upper thermal load of the product, so make sure
that the product is not damaged as a result of an excessively high outlet temperature.
10. As soon as the desired operating conditions have been achieved and are stable, change the feed
tube from pure solvent to the prepared feed solution.