HH-S4 Thermostatic Digital Two-Row Four-Opening Laboratory Water Bath

Experimental principle: 

  The devices of the thermostat are various. It mainly includes the following components: 1 sensitive component, also known as temperature sensing component; 2 control component; 3 heating component. The temperature sensing element converts the temperature into an electrical signal for delivery to the control element, and then the control element issues an instruction to heat or stop heating the electrical heating element. Picture 1-1 

Figure 1-1 is a thermostat. It consists of a bath, a heater, a stirrer, a thermometer, a temperature sensing element, a thermostat controller, etc., and is described as follows:

  

  1, bath: usually used 10dm3 cylindrical glass container. Distilled water is generally placed in the tank. If the temperature is above 100 ° C, liquid paraffin and glycerin can be used. The range of temperature control is different, and the medium in the water bath is also different. Generally speaking: -60 ° C ~ 30 ° C with ethanol or ethanol aqueous solution.  Use water at 0 °C ~ 90 °C.  Physical and chemical experiments (1) Experiment 1 Assembly and performance measurement of thermostat

2. Use glycerin or glycerin aqueous solution at 80 °C ~ 160 °C.  Use liquid paraffin, silicone oil, etc. at 70 ° C ~ 200 ° C.

                        Figure 1-1 Thermostat device diagram

1 - Bath 2-battery 3-Agitator 4-thermometer 5-temperature sensing element (thermistor probe) 6-thermometer 7-Beckmann thermometer

Heater: The electric heater is commonly used. Our electric heater puts the electric resistance wire into the annular glass tube and bends it into a ring according to the diameter of the bath. It distributes the heat released by the heating wire evenly around the circular thermostat. The electric heater is automatically adjusted by an electronic relay to achieve a constant temperature. The power of the electric heater is determined by the capacity of the thermostatic bath, the temperature controlled by the constant temperature, and the temperature difference with the environment. It is preferable to make heating and stop heating for half of each time. In order to improve the effect and accuracy of the constant temperature, we connect a 1kV adjustable transformer between the thermostat controller and the electric heater. The circuit diagram of the thermostat is as follows:

                            Figure 1-2 Thermostat circuit diagram

At the beginning of the experiment, because the temperature difference between the room temperature and the constant temperature is large, in order to reach the constant temperature as soon as possible, we will increase the output voltage of the series, and when the temperature is gradually close to the constant temperature, in order to reduce the hysteresis, The output voltage of the adjustable transformer is reduced, which can better improve the accuracy of the temperature control of the constant temperature bath. 

  3. Stirrer: Generally use a power stirrer with a power of 40W, and connect the electric stirrer in series on a variable transformer to adjust the stirring speed so that the temperature of the constant temperature tank is as uniform as possible. Where the agitator is installed, the shape of the paddle has a large effect on the agitation effect. For this purpose, the agitating blades should be propeller-type or turbine-type, with appropriate number, diameter and area to allow the liquid to circulate in the thermostat to ensure uniformity of the overall temperature of the bath.

  4. Thermometer: The temperature of the constant temperature bath is often measured by a 1/10 °C thermometer in the constant temperature bath. The sensitivity of the bath was measured with a Beckman thermometer. The thermometer used must be calibrated and standardized before use.

                         Figure 1-3 temperature control schematic

Ningbo Scientz Specializing in the production of a variety of thermostat equipment, the products are exported to more than 30 countries in the United States, Britain, South Korea, Russia, etc., received the praise of customers.

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