n
Figure 8
Never insert foreign objects in the vessel when
the mixer is operational.
To avoid dry running the speed has to be adjusted in
accordance to the level in the tank. This will depend on
the following:
• The diameter of the tank.
• The shape of the bottom of the tank.
• The viscosity; as viscosity increases, the flow through
the impeller decreases.
The above are process and installation parameters, not
mixer parameters. Specific maximum speed for an appli-
cation is not dictated by the mixer, but by the combination
of mixer, tank, process fluid and purpose of mixing.
4.5. Further operational advice
The impeller is factory cleaned prior to delivery. How-
ever, before it is put into service it must be cleaned in an
appropriate manner so that it is free from foreign parti-
cles, followed by CIP and/or SIP cycles as required by the
application.
The operational parameters are pre-set in the control
box (applies only to Steridose-supplied control boxes). In
extreme working conditions, uncoupling of the magnetic
coupling can occur, i.e. the motor rotates, but not the im-
peller. To avoid any uncoupling of the magnetic coupling,
the acceleration time (ramp up) and the maximum rpm
should be adjusted to conform to the specific application.
For a Sterimixer/Sanimixer supplied without a control
box, soft manual start of the motor is required to prevent
the magnetic coupling becoming uncoupled. A suitable
acceleration time up to the maximum rpm can be anything
from ten seconds to a couple of minutes depending on the
application.
CAUTION:
Never insert foreign objects in the vessel
when the mixer is operational.
4.5.1. Cleaning
guidance
for
SMA-type
impeller
equipped Sterimixers
The Sterimixer is designed for optimum performance in
cleaning in place (CIP) without any need for dismounting.
n
Figure 9
Succesful cleaning of the impeller relies on a
combination of the self-cleaning flow through design of the
SMA-type impeller, the cleaning-agent used and respecting
the prescribed time and temperature.
The flow channels in the impeller provide a process fluid
flow through the bearings. In order to achieve this, the
impeller should be covered with fluid and rotated at a
certain minimum speed. The flow of the process fluid
through the flow channels is very much determined by
the rotational speed of the impeller.
The result of the cleaning is dependent on many param-
eters such as temperature, time, and chemical composition
of the cleaning agent, mechanical conditions, speed and
the type of product to be removed.
The cleaning usually consists of several cycles e.g. pre-
rinse, cleaning with base and/or acid cleaning agents,
main rinse following acid or base cleaning, and a final
rinse.
+
NOTICE:
To achieve the optimal cleaning effect the
impeller should be covered with cleaning agent and
rotating.
Example of CIP procedure for SMA-type impeller:
1. Drain the vessel of process fluid.
2. Close the outlet and fill with cleaning agent having
the fluid level above the impeller with at least 150 -
200 mm.
3. A suitable speed is approximately 300 rpm with filled
vessel (depending on the size).
4. Normal cycle time is 5 - 20 minutes.
+
NOTICE:
The exact operational conditions for CIP must
be validated for each individual application.
+
NOTICE:
The cleaning method described above does
not remove any magnetic particles. Due to the strong
magnets inside the impeller all magnetic particles will
be stuck inside the impeller. To have these removed,
the impeller must be removed and cleaned separately.
Magnetic particles stuck to the impeller may cause dis-
colouration of the impeller surface.
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Installation & Operation
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