Ross CDA-10, Installation, Maintenance And Operating Manual

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© 2017 CHARLES ROSS & SON COMPANY
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5. When all of the materials have been added, increase the shaft speed of the mixers to the appropri-
ate tip speeds to allow for de-agglomeration/dispersion, mixing/blending and agitation. Proper tip
speeds are as follows:
- Agitation = 400 - 1200fpm.
- Mixing/blending = 2500 - 3500fpm.
- Dispersion = 4800 - 5200fpm.
6. Tip speed formula: Blade dia/12 x 3.1415 x shaft speed = FPM.
E. VACUUM MIXING.
Mixing under vacuum is normally used to remove air from the batch but may also increase the evaporation
of other volatiles such as solvents or wetting agents. The reaction of each formula to vacuum is different and
should be closely monitored during trial runs. The horse power requirements may change when mixing un-
der a vacuum along with the product viscosity. Air attached to "dry" particles or between wet surfaces will
be removed which will effect the rheological aspects of the batch.
1. Induction of dry powders while operating under vacuum is only recommended when introduced
from below the fluid level and into a "shear zone" to prevent dusting and quick wetting of the pow-
ders. Normally this is done through a valve installed in the bottom of the mixing vessel.