|
For
over 30 years, researchers have depended on Talboys overhead
mixers to deliver performance, durability, and quality
at an economical price. From general purpose, light duty
mixing to heavy duty, high viscosity mixing, Talboys has
a mixer for your laboratory's application. With our extensive
offering of mixing paddles, stands and clamps, you're
sure to find a complete mixing solution from Talboys.
Laboratory Mixers QuickLINKS:
> Light Duty Mixers
> High Speed Mixers
> Medium Duty Mixers
> Heavy Duty Mixers
> Mixer Chucks
> Mixer Stands and Support Clamps
> Propeller Paddles, Shafts, and Blades
There
are a number of factors to consider
when choosing the most efficient
overhead system for your needs
and requirements. Talboys recognizes
these needs and has created
a checklist of critical components
for our customers to review
when making such a purchase.
Step 1: Helpful Tips on Choosing the Paddle that Best Meets
Your Needs
We
realize that selecting the proper paddle can be a frustrating
process, but Troemner has devised a method that will help
you choose the best solution for your needs. Experimentation
is the key to finding exactly what you need. A blend of
experimentation and your own experience will reward you
with the answer you need for your projects.
The critical factors to consider when selecting a paddle
include:
- the viscosity of the fluid
- the power of the stirrer you are using
- the amount of agitation desired
- the volume of fluid to be mixed
- the speeds at which you must mix
- the size and shape of your vessel
It is pertinent to keep in mind that slow speed mixing is
more efficient than high speed mixing. High speed mixing
may tear a hole in the center of the fluid, generally
resulting in high local agitation and lower overall agitation.
The volume and shape of the vessel has often been overlooked
when selecting a paddle. These two attributes, however,
are very important. Here's why:
- Will the selected paddle fit into the opening in the vessel?
- Is the fluid volume suited to the vessel so that there
is sufficient depth to mix properly?
- What is the volume in comparison with the power of the stirrer/paddle
combination? The following analogy best explains this:
an outboard motor has little, if any, effect in the
ocean, but if that outboard motor is operating in a
fifty-five gallon drum, the agitation is significant.
The power required to drive a given stream of fluid is a function
of rpm and the paddle diameter. Selecting a 3-1/2"
propeller over a 2" propeller will produce more than
sixteen times the load seen by the stirrer. An extra propeller
added to the shaft will produce greater agitation but
limit the load on the motor.
Step 2: Helpful Tips on Choosing the Stirrer that Best
Meets Your Needs
Selecting
a stirrer is very similar to buying a new car. The options
you select will be based on your needs and how much you
can afford to pay for them.
When
choosing a stirrer that will be used for very generalized
requirements, select a model that provides the greatest
versatility yet fits within your budget. If you have a
specific stirring issue, the selection process becomes
more difficult. Listed below are some ways to find the
best stirrer for your needs, even when your project is
a bit complicated.
- Choose
a paddle that produces the desired agitation.
- Ensure
that the stirrer you choose turns the paddle at the
needed speed. This will be a trial and error process,
especially if there is a load change during the stirring
operation.
- Use
the motor's torque ratings to select the best stirrer.
Torque combines the function of horsepower and speed,
so you can gain valuable insight from such an evaluation.
An
Explanation of Torque and Horsepower
When
measuring horsepower, the torque increases as the rated
motor speed decreases and vice versa. This statement is
true only if the output speed is changed by mechanical
means, such as gear reducers. Electronic speed controls
will not change the torque.
- Many
speed controls reduce motor speed while they reduce
the torque.
- Transistorized
SCR type speed controls, like the Talboys Transi-Stir
Control, reduce motor speed, but the torque remains
constant.
- Gear
reducers reduce the speed while causing a directly proportional
increase in torque. The horsepower remains constant.
The
horsepower rating of a motor is the maximum available
horsepower of that motor. The running conditions of a
stirrer can be confirmed by measuring speed with a tachometer
or a probe and by measuring the motor current with an
ammeter. The volume of fluid being agitated has little
influence on the size of the motor required, but should
be considered when selecting the paddle.
Your current project specifications, your experience, and your
laboratory supplies distributor will be helpful in ensuring that
you find the best solution to your needs. If you are still having
trouble determining which stirrer will best fit your project, Troemner's
customer service department is available to assist you with your
purchase. Please call 1-888-TALBOYS.
Types
of Speed Control
Electronic Speed Control
The Talboys electronic speed control is a compact, low
cost speed control chosen for its reliability. This solid-state
electronic voltage control offers:
- Variable
speed over the motor range.
- An
engineering design that withstands a 300 percent overload.
- Minimal
heat production.
Transi-Stir Speed Control
The Talboys Transi-stir speed control is a solid-state
controller, similar to the electronic speed control. It
provides:
- The
ability to maintain desired speed even when there are
changes in viscosity.
- Capabilities
to sense increased resistance, thus sending more speed
to maintain momentum.
- Full
motor torque over a wide range of speeds. The result
is more torque over a wider speed range than with other
types of speed control.
Overload
Protection
Some model stirrers offer an internal thermal overload protection
cut-off. This will be noted in the product descriptions. When the
motor gets too hot, the cut-off feature shuts down the motor. Once
it has cooled, the motor will restart.
CAUTION:
- If
the cut-off stops the motor, be sure to turn the switch
to OFF and determine why the motor went into overload.
All model stirrers (with the exception of Models 105
and 107) are equipped with fuses as an integral part
of the circuitry. A current overload will blow the fuse
and shut off the motor.
- Any blown fuse should be investigated. It is possible to blow
a fuse by turning on the power to a unit with the speed control
set at any value above zero. Be sure to set the speed at zero
before flipping the switch. Never use the power cord to start
and stop the unit.
Overseas Voltage
Several Talboys mixers are available in 230 Volts for overseas
usage. Models 238 and 429 are available in 230V. Other models, which
are available in 230V, can be shipped by special order. These 230V
stirrers are sold without power cord plugs. Please contact Troemner
at 1-888-TALBOYS for further details and delivery information.
PTFE Coating
Many
of the Talboys accessories are available with PTFE coating.
The PTFE resists many laboratory substances. The PTFE
used is generally between 0.001" and 0.002"
thick.
Flammables
Talboys stirrers are electric, but they are not explosion-resistant.
The overhead stirrers should never be used with flammables. Use
of an electric stirrer in a hazardous location can cause fire and/or
explosion resulting in operator injury and damage to facilities.
Troemner does not assume liability for such damage.
Warranty
Talboys
stirrers come with a two-year limited parts and labor
warranty. Warranties are not available for brushes, springs,
gears, and other minor equipment because they are normal
maintenance components.
Top
|
