How to Automate Overhead Stirrer Operations

Overhead stirrers are called upon to perform multiple mixing tasks in R&D labs.  When several of these versatile overhead mixers such as offered by CAT Scientific are employed in the lab the researchers’ monitoring tasks are greatly simplified if the equipment is managed by a PC.  This post describes how to automate overhead stirrer operations.

The computer program is designed to individually control different lab instruments at the same time. For example it can be used for

  • Overhead stirrers
  • Standard and hotplate magnetic stirrers
  • Bottle-top burettes
  • Micro-metering pumps

This is accomplished by assigning different “slave” addresses to each unit connected to the computer. That way the computer can access each unit individually. This sure beats lab assistants moving up and down aisles to check on the performance of each piece of equipment.

A Closer Look at Automating Stirrer Operations

First of all, a brief intro to lab overhead stirrers.  If you’re familiar with these versatile mixing devices, feel free to skip to the next section.

Where Overhead Stirrers are Used

An overhead stirrer is an example of several means by which ingredients can be blended as part of a research or pilot plant operation.

Powered by a drive motor affixed to an adjustable support stand they use impellers, paddles and blades to blend ingredients in the sample containers.  Their drive motors are specified by torque power necessary to work with samples based on viscosity, and by stirring speed and duration.

Self-test features will shut the equipment down in the event of overheating or sample viscosity exceeding the unit’s limits.

CAT Scientific offers several models of laboratory overhead mixers.

In general, all have adjustable speed control (typically 50 to 2000 RPM) and basic LED displays.  Higher end mixers display set and actual parameters along with other operational details. When used alone, RS232 interfaces can be used to operate an overhead stirrer by computer and collect operating data for record keeping.

See below for a CAT overhead stirrer close-up.

The Automation Operation

As suggested above, multiple experiments or pilot plant trials utilizing overhead stirrers as part of the mixing procedures are greatly simplified when overhead mixers can be individually controlled via a computer program.  In response to this a Windows-based PC program with comprehensive user interfaces provides researchers the option of manually or automatically controlling overhead stirrers.

Developed by CAT for its R series of lab equipment the software is easily installed into a PC.

Once installed it shows a collapsible split-screen display.  On the left the researcher enters data for each of the stirrers to be managed by the software, the top half of which is for manual control and the bottom half for automated control.

The manual control interface on the left panel provides time and speed options.  The bottom automatic control interface allows users to set time, start speed, stop speed and maximum torque options.

When these parameters are established the screen can be collapsed to show only the actual operations.  It will indicate:

  • Stirrer type, such as the CAT R100C (described below)
  • The control mode (stirrer will be controlled via the stirrer panel, manual control with the manual control interface and auto control via the automatic control interface)
  • Set and actual speed in RPM
  • Absolute and relative torque in Ncm
  • Absolute and relative power in watts
  • Set and elapsed stirring time

Other options and data include a panel update, when maximum torque is reached (in which case it will not be exceeded due to automatic reduced motor speed), frequency of data recording, an emergency stop, and data acquisition.

A CAT Scientific Overhead Stirrer Close-up

The microprocessor controlled CAT Scientific R100C overhead stirrer is the universal stirring motor for rheometric tests.  It delivers 150 Ncm torque energy and operates from 30 to 2,000 rpm. with higher speeds available on request.  Operational data are digitally presented on the control panel.

A dream to operate, the smartly styled 220-watt R100C stirrer can be PC controlled and features soft start and stop to avoid sample splashing.  Adding to its versatility the CAT 10.5 mm chuck accommodates a variety of stirrer configurations.

The unit’s robust, acid-resistant construction provides years of reliable service life, enhanced in part by a self-test feature that will shut the unit down if overloading or overheating occurs.    A variety of paddle configurations are available for stirring and dissolving applications.

More Info on Automating Overhead Stirrer Operations

The scientists at CAT Scientific are ready to help you select the right equipment for your research and manufacturing needs.  To get started all you have to do is contact us and provide some preliminary information.  We promise to get back to you soon.

 

Bob Wilcox

Bob Wilcox has represented CAT Scientific’s family of homogenizers, magnetic stirrers, liquid handling and related laboratory equipment since 2002 when Staufen, Germany-based CAT Ingenieurbüro M. Zipperer GMbH established operations in North America. Bob oversees CAT Scientific laboratory apparatus sales and service organization from the company’s headquarters in Paso Robles, CA. He also is in charge of the parent company’s line of JetCat jet turbines, turboprop, and helicopter power plants for hobbyists’ radio controlled fixed wing and helicopter model aircraft. -- Earlier in Bob’s career he was involved in visual and special effects as well as camera and electronics supervisory responsibilities for the motion picture and television industry.

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