Definition
The heated magnetic stirrer is a universal laboratory device that integrates heating and magnetic stirring functions. It uses a magnetic field to drive the agitator inside the vessel to rotate to achieve liquid mixing while temperature control of the vessel through a built-in heating system. The instrument is widely used in sample preparation, reaction process optimization and physical property research in chemistry, biology, food, materials and other fields.
How it works:
The working principle of the heated magnetic stirrer is based on electromagnetic induction and resistance heating technology. The instrument is equipped with a rotating magnet or electromagnetic coil, which generates a rotating magnetic field after energizing and drives the magnetic stirrer placed at the bottom of the container to rotate synchronously, thereby driving liquid mixing. The heating part usually uses resistance wires or ceramic heating plates to convert electrical energy into heat energy, which heats the bottom of the container through heat conduction. The temperature control module monitors the temperature of the heating surface through sensors and feeds back to the control system to achieve precise maintenance of the set temperature.
The regulation of stirring speed and heating power usually follows a linear or proportional relationship, and its basic control formula can be expressed as:
P = k × V and T = f(P, t), where P represents heating power, V represents regulation voltage, k is the proportional coefficient, T is the actual temperature, t is the time, and f is the transfer function of the control system.
Measurement and operation methods
Routine operations include placing the vessel, feeding the agitator, setting the temperature and speed parameters, and starting the operation. The measurement process mainly involves monitoring the mixing speed and heating temperature. The mixing speed is typically measured in revolutions per minute (RPM) and is indicated by a digital display on the instrument panel or on a knob scale. Temperature measurement relies on built-in thermocouples or thermal resistance sensors that display the actual temperature value in real time. For accurate experiments, it is recommended to use an externally calibrated temperature probe to measure the temperature directly of the solution to reduce system error. After the operation, the temperature and speed should be gradually reduced to avoid sudden changes in the solution.
Influencing factors
The stirring effect is affected by the shape, size and material of the agitator, and the common agitator is a magnetic material coated with polytetrafluoroethylene, and its geometric design affects the shear force and mixing efficiency of the fluid. The viscosity and volume of the solution directly affect the mass and heat transfer processes, and the equipment with strong driving force should be selected for high-viscosity liquids. The flatness of the bottom of the container and the thermal conductivity of the material affect the temperature uniformity, and it is generally recommended to use round or flat borosilicate glass containers. Ambient temperature and ventilation conditions may cause slight interference with the stability of temperature control during long-term operation. In addition, the matching degree between heating power and stirring speed should be adjusted according to specific reaction conditions to avoid local overheating or insufficient mixing.
Applications:
In chemical synthesis, this equipment is used to promote uniform mixing of reactants and temperature control to improve reaction efficiency. In biological experiments, it is often used for pretreatment steps such as medium preparation and bacterial solution mixing. It is used in the food industry for sample extraction, ingredient mixing and viscosity testing. In the field of environmental detection, it can be used for the pretreatment of water samples and the dissolution of reagents. In materials science, it is used for stirring and constant temperature in nanomaterial preparation, solution spinning and other processes. Its versatility makes it one of the basic equipment for routine laboratory operations.
Selection reference
When selecting a model, it is necessary to comprehensively consider the heating temperature range, temperature control accuracy, stirring torque, working plate size and safety functions. For high-temperature reactions, it is necessary to choose a model that meets the needs at the highest temperature and has good heating uniformity. High viscosity or large-range solutions should be selected with sufficient torque and stable speed. If the experiment involves corrosive solvents, attention should be paid to the corrosion resistance of the worktop material. In terms of safety, models with overheating protection, abnormal alarms, and anti-slip floor pads can be considered. In addition, equipment operating noise, energy consumption level and maintenance convenience can also be used as reference factors for long-term use. It is recommended to conduct a comprehensive comparison based on the core parameters of actual application scenarios.