Table of Contents
Introduction
1. Heating Power
2. Heating Precision
3. Heating Accuracy
4. Stirring Power
5. Stir Bar Configuration
6. Ease of Use
7. Safety
Summary and Recommendations

Introduction

1. Heating Power

Imagine completing your experiments faster than ever before. Precise temperature control is essential in labs, where accuracy can mean the difference between success and failure. With the Guardian 7000 and Guardian 5000 models, the SmartRate™ heating system allows you to switch between rapid or controlled heating depending on the sensitivity of your samples and to better suit your application.

• Rabbit Mode:

  • Rapid heating for fast-paced experiments.

  • Achieves target or set temperature more rapidly.

• Turtle Mode:

  • Slow and controlled heating.

  • Ideal for sensitive samples.

  • Prevents overshooting target temperature.

2. Heating Precision

Tight temperature control is essential to chemistry processes. It allows consistent experimentation regardless of exothermic reactions, provides safety from runaway reactions, and enables the ability to simulate and scale up production accurately. That’s why it’s critical to choose a hot plate stirrer that minimizes overshoot and maintains stable temperature over time.
 

The Guardian Hot Plate Stirrers are the ideal choice because they are designed with precision and accuracy in mind. They offer advanced temperature control, minimizing overshoot and maintaining stability. The Digital Guardian models (Guardian 7000, Guardian 5000, and Guardian 3000) provide additional temperature control with the option to use an external temperature probe. This ensures that the set temperature is based off of the sample and not off of the hot top alone.

3. Heating Accuracy

4. Stirring Power

The Guardian Advantage

Unlike many other hot plate stirrers, Guardian Stirrers allow you to fine-tune the stirring speed to match your needs, avoiding common issues like splashing, spillage, or decoupling of stir bars. The magnetic coupling strength of Guardian Stirrers further ensures reliable, consistent mixing every time, even with difficult samples.

The Guardian 7000 and Guardian 5000 models, equipped with the SmartRate™ feature, offer customizable stirring speeds to suit your specific needs:

• Default Mode: Optimized for most applications, efficiently adjusting stirring speed for optimal coupling and mixing.

• Turtle Mode: Gentle stirring for viscous fluids, preventing decoupling and ensuring even mixing.

• Rabbit Mode: Rapid stirring for less viscous materials, allowing quick, efficient homogenization.

Comparison to Competitors

Below, you'll find a comparison of our Guardian models against three leading competitors, based on a series of tests conducted using 1L of silicon fluid in a 2L Erlenmeyer flask:

Unlike many other hot plate stirrers that use traditional Neodymium (NdFeB) magnets, the OHAUS Guardian 5000 stirrers are equipped with high-performance, high-quality Samarium Cobalt (SmCo) magnets. In contrast to traditional Neodymium (NdFeB) magnets used by some competitors, SmCo magnets found in OHAUS Guardian 5000 stirrers maintain their performance at high temperatures and offer superior chemical resistance. This is especially important for applications involving high-temperature processes or exposure to harsh chemicals.
 

5. Stir Bar Configuration

Selecting the right stir bar is crucial for ensuring efficient and effective mixing in your lab applications. Consider these key factors:

1. Vessel Size and Sample Volume

• Smaller vessels: Opt for smaller stir bars to prevent unnecessary turbulence and ensure precise mixing.

• Larger vessels: Employ larger stir bars for thorough mixing of larger volumes, maintaining consistency and efficiency.

2. Vessel Shape

• General guideline: A good rule of thumb is that the stir bar length should be about two-thirds of the vessel's bottom diameter for optimal stirring performance.

3. Stir Bar Types:

• Multifaceted Flat:

  • Gentle Mixing: Ideal for low-to-medium stirring applications requiring gentle mixing and minimal turbulence.

  • Prevents Settling: The absence of a pivot ring allows the stir bar to stay close to the bottom of the vessel, preventing material from settling and ensuring thorough mixing.

• Multifaceted Surface with Pivot Ring:

  • Enhanced Mixing: Generates turbulence for efficient mixing, even in challenging applications.

  • Versatility: Supports a wider range of vessel sizes and higher stirring speeds.

  • Smooth Operation: The centered pivot ring (pictured below) minimizes the contact area between the stir bar and the vessel bottom, reducing friction and preventing the "chattering" sound often associated with stirring. This results in a smoother, quieter stirring process.

By carefully considering vessel size, sample volume, vessel shape, and stir bar type, you can select the optimal stir bar for your applications. OHAUS Guardian Stirrers offer a wide range of stir bar options to ensure efficient and effective mixing, helping you achieve reliable results in your experiments.

6. Ease of Use

Time is of the essence in any lab. The OHAUS Guardian Series, with its intuitive controls and features, is designed to maximize your productivity and streamline your workflow. Here’s how:

• Dual-Knob Control: Our Guardian Hot Plate Stirrers offer two independent knobs for heating and stirring functions, allowing for quick adjustments without the hassle of toggling through menus with just one knob.

• Large, Clear LCD Displays: With the Digital models (Guardian 7000, Guardian 5000, and Guardian 3000), you can easily monitor your settings with large, easy-to-read LCD displays, making it easy to set parameters at a glance.

• Visible Timer: With the Guardian 7000 and Guardian 5000 models, you can keep track of your experiment’s progress with the built-in timer function.

• Heater Indicator Bar: Exclusive to the Guardian 7000, you can watch as your heater progresses toward the set temperature with the illuminating indicator bar.

• 5-Step Programming: The Guardian 7000 model allows you to automate your workflows with pre-set heating, stirring, and timing settings for added convenience. This means less time spent adjusting settings and more time focusing on your experiments.

7. Safety

While essential laboratory tools, hot plate stirrers can pose potential hazards like burns, fires, and electrical shock. To mitigate these risks, consider the following when buying a hot plate stirrer:

1. Choose products certified by Nationally Recognized Testing Laboratories (UL, CSA, TUV, etc.): Ensure your equipment meets rigorous safety standards.

2. Invest in Overtemperature Protection: Look for stirrers with built-in safeguards to prevent overheating and potential fires.

3. Consider Products with Separate On/Off Switches: Separate on/off switches will give you precise control over the heating and stirring functions.

4. Consider Models with Automatic Shut-Off Features: Minimize the risk of accidents by choosing a stirrer that automatically turns off when left unattended.

5. Make your work area safe: Keep plastic, paper, and other combustibles at least six (6) inches away and keep flammable solvents at least two (2) feet away, even when not in use
   

Safety is paramount when dealing with high temperatures and hazardous materials in the lab. The OHAUS Guardian Series is designed with uncompromising safety in mind, offering several advanced safety features:

• SafetyHeat™: An industry-leading overheat protection system with dual safety controls, safeguarding against potential hazards. Available on the Guardian 7000, Guardian 5000, and Guardian 3000 models.

• SmartPresence™ and SmartLink™: Automatically shuts off the heater if no one is present or if the Bluetooth connection is lost—perfect for preventing unattended heating accidents. Exclusive to the Guardian 7000 series.

• Hot Top Indicator Light: 13mm Hot Top Indicator light that remains lit even after the unit is off, ensuring lab personnel are aware of hot surfaces. Available on the Guardian 7000 model.

• RunDry Protection: Shuts off heating and alarms audibly, if a probe-controlled heating is running without the probe tip immersed in the sample.   
   

These safety features are vital for labs, where accidents can have severe consequences. Choosing Guardian ensures not only superior performance but also peace of mind in maintaining a safe working environment.

Summary and Recommendations

Why the OHAUS Guardian Series Is the Best Choice for Labs

OHAUS Guardian Series is the go-to choice for laboratories seeking high-performance, precise, and safe hot plate stirrers. With their advanced features and exceptional quality, OHAUS Guardian Stirrers offer unmatched performance in a variety of laboratory applications. Whether you need rapid heating, precise temperature control, or reliable stirring for sensitive applications, the Guardian Series is designed to meet your needs.

Key Benefits of the Guardian Series:

• Precise temperature control: Ensures accurate and consistent results.

• Customizable stirring speeds: Accommodates different sample viscosities and experimental requirements.

• Superior magnetic coupling: Minimizes decoupling and ensures reliable mixing.

• Advanced safety features: Protects against potential hazards and ensures a safe working environment.

• Ease of use: Intuitive controls and user-friendly features streamline workflows.

Selecting the Best Guardian Model for your lab needs:

• Guardian 7000: Ideal for complex, multi-step processes requiring advanced temperature control, external probes, and automated workflows.

• Guardian 5000: Perfect for labs needing customizable stirring and heating with superior magnetic coupling for reliable mixing.

• Guardian 3000 and Guardian 2000: A cost-effective solution for labs requiring basic but reliable heating and stirring without sacrificing precision.

No matter which model you choose, the OHAUS Guardian Series ensures optimal performance and safety, making it the obvious choice for laboratory professionals across a wide range of industries and applications.

Upgrade to OHAUS Guardian today and experience the difference in your lab’s efficiency and results.