Definition
A thermostatic timing stirrer is a universal laboratory equipment that integrates temperature control, timing function, and stirring operation. It mixes samples evenly through mechanical stirring and maintains a constant temperature environment for a set time, making it suitable for sample preparation and reaction processes in many fields such as chemistry, biology, food, and environment.
Principle
The equipment is mainly composed of heating module, temperature sensing module, stirring module and timing control module. The heating module usually uses electric heating wire or PTC element to generate heat through energy conversion; The temperature sensing module (such as platinum resistor or thermocouple) monitors the sample temperature in real time and feeds the signal back to the control circuit to adjust the heating power through the PID algorithm to achieve temperature stability. The stirring module is driven by a motor to drive the stirring paddle, creating a vortex or convection that allows the sample to be thoroughly mixed. The timing control module automatically starts and stops the device based on the preset time, and its time control accuracy usually depends on the stability of the internal crystal oscillator.
Measurement method
In the performance evaluation of thermostatic timing agitators, the measurement of key parameters must follow the relevant standards. Temperature uniformity can be assessed by placing temperature sensors at multiple points in the sample container, recording the temperature values at each point after stabilization, and calculating their standard deviations. The mixing speed can be measured using a non-contact tachometer for readings by aligning the mixing shaft with a tachometer. Timing accuracy can be verified by comparing the set time of the device with the actual running time recorded by a standard timer. Among them, the temperature stability TsIt can be expressed as: Ts = (Tmax - Tmin)/2, where Tmaxand TminIt is the extreme value of temperature fluctuations within a specified time.
Influencing factors
Equipment performance is affected by a variety of factors. The material and shape of the sample container will affect the heat conduction efficiency and hydrodynamic properties. Fluctuations in ambient temperature may cause deviations in the temperature control system; If the geometric size and position of the mixing paddle are not set properly, it may cause local temperature unevenness or vortices; When the viscosity of the sample is high, the stirring speed needs to be adjusted to ensure the mixing effect. The stability of the power supply voltage will also indirectly affect the long-term stability of the heating and temperature control module.
Applications
Constant temperature timer stirrers are widely used in the field of non-medical drugs. In chemical synthesis, it can be used to promote reactant mixing and temperature control; In the food industry, for uniformity testing of sauces or beverages; In environmental testing, it can be used for constant temperature stirring extraction of water samples. In materials science, it is used for the preparation of nanomaterials or the mixing of coating solutions. Its versatility makes it a reliable tool for routine laboratory operations.
Key points of selection
When selecting, it is necessary to comprehensively consider technical parameters and actual needs. The temperature range should cover the required range of the experiment, and pay attention to its temperature control accuracy. The stirring speed range needs to match the viscosity of the sample to ensure sufficient shear force is provided; The timing function needs to meet the time control requirements of the experimental process. In terms of material compatibility, it is necessary to ensure that the contact parts of the equipment are resistant to the chemicals used. In addition, the user-friendly design of the user interface, safety protection features (such as overheating protection) and ease of maintenance are also considerations for long-term use.