Canadian Finishing & Coatings Manufacturing Magazine Jan/Feb 2023 - 49

PAINT AND COATINGS MANUFACTURING: PORTABLE MIXERS
the tank (only position the prop one diameter from the bottom
when mixing slurries or products with solids) to gauge shaft
length.
Mixer Agitation Rate
Different applications necessitate different agitation rates, so it
is important to know the degree of agitation required. Agitation
rates range from mild to violent, with tank turnover varying from
1/2 turns to more than three turns per minute.
* Mild: Half to one tank turnover per minute.
* Medium: One and a half to two tank turns per minute.
* Vigorous: Two and a half to three tank turns per minute.
* Violent: Greater than three tank turns per minute.
Consult with mixer manufacturers to determine the prop's
pumping rate for a specific model type and size at the various
rpms at which they will operate. These rates are normally
measured in liters per minute (l/min) or gallons per minute
(gpm) of water pumped. Use this information to select the right
agitation rate. For example, a 378-liter (100-gallon) tank of a
water-like chemical requires vigorous agitation, or two and a half
turnovers. Knowing that a four-inch square pitch prop at 1,750
rpm delivers a pumping rate of 496 l/min (250 gpm), a portable
mixer could be selected. Keep in mind, however, that as liquid
viscosity increases the pumping rate decreases.
Mixer Positioning
The positioning of the shaft and prop within the mixer
container is vital to enabling any portable mixer to blend, dissolve
or disperse effectively.
In most mixing applications involving small cylindrical tanks
of 3,785 liters (1,000 gallons) or less, the mixer is clamped to the
side of the container. Effective mixing patterns will be achieved
if the mixer is angled 10 to 15 degrees away from the vertical,
either off-center or on-center. When mixing a slurry, angling the
mixer 15 to 20 degrees off the tank's centerline will result in good
material turnover. On-center angling is better for gentler mixing
and creates a vortex. Vortexing occurs when the contents of the
tank swirl around the walls of the tank without much top-tobottom
turnover; this creates a less-efficient mixing operation
and the possibility of uneven mixing or blending.
Cylindrical tanks with capacities of more than 3,785 liters
(1,000 gallons) may require that the mixer be mounted directly
in the center of the tank with the shaft in a vertical orientation.
In this configuration, it is recommended that the operator put
baffles on the walls of the tank in order to prevent the contents
of the tank from turning in the direction of the mix, or creating
an inefficient vortex. When this occurs, the mixing action in the
tank will be poor.
Be advised, though, that the presence of vortexing during
the mixing or blending process is not always detrimental. For
example, creation of a vortex is desirable when solids or powders
are added to the top of the batch, or liquids need to be drawn
rapidly into the batch. The level of vortexing also becomes less
severe with fluids that have higher viscosities.
It's a fact that portable mixers play a key role in industrial
manufacturing or fluid-handling applications. The right mixer
can streamline any operation and provide operators with a
consistent, hassle-free experience. By ensuring that you select
the proper mixer for your specific situation, you can gain an
January/February 2023
49
important advantage towards optimizing any fluid mixing
application.
Eulis Ester is a product manager for Neptune, a provider of systems
for handling of critical chemical fluids for water-treatment
processes and agriculture applications.
ROSS High Shear Mixer
Designed with efficiency and mobility in mind, the
ROSS Model HSM-405SC-25 Inline High Shear
Mixer with Solids/Liquid Injection Manifold (SLIM)
Technology is for production floors that require
flexibility. The easy-to-clean stainless steel portable
skid with built-in workbench saves time and money
as it allows the mixer to be used anywhere in a
plant. This eliminates the need for multiple mixers
separately dedicated to each vessel or product. As
an external mixer, the Inline SLIM can be piped to
the recirculation loop of virtually any size vessel.
Featuring sanitary tri-clamp connections, this
3A-compliant machine can be cleaned in place (CIP)
but is also quick to disassemble for deep cleaning
and sanitation.
The SLIM is a rotor/stator device capable of
injecting powders directly into a fast-moving liquid
stream without the use of an eductor or pump.
Engineered for high-speed and high-volume mixing
requirements, this device offers a straightforward
method of wetting out powders and creating
a fine immediate dispersion, greatly reducing
the occurrence of floating powders, lumps, and
agglomerates. Using the tabletop workbench,
operators can conveniently open bags and load
powders into the hopper that sits on top of the mixer,
ensuring a consistent feed and minimizing aeration.
Canadian Finishing & Coatings Manufacturing Magazine Jan/Feb 2023

Table of Contents for the Digital Edition of Canadian Finishing & Coatings Manufacturing Magazine Jan/Feb 2023
