Construction of Thermostat
The structure of a thermostat: The thermostat consists of a constant temperature bath, heater, stirrer, temperature regulator (also known as mercury ammeter), relay, thermometer, etc.
(1) A constant temperature bath is usually made of a glass tank or metal pot, which contains water (or oil). To prevent the growth of enzymes and bacteria in the bath, it is important to change the water regularly. For constant temperature baths above 40 ℃, a layer of paraffin or olive oil (soybean oil is also acceptable) should be added to the water surface to prevent excessive evaporation of water.
(2) The commonly used heater is an electric heater. The power of its electric heating wire depends on the size of the constant temperature bath and the required temperature.
(3) The mixer used in the thermostat is usually an electric mixer, which should be able to stir vigorously to achieve uniform temperature in the constant temperature bath.
(4) Temperature regulator is the main equipment for controlling the constant temperature inside the constant temperature bath. Its function is to automatically heat the electric heater when the temperature of the constant temperature bath is lower than the required temperature; When the desired temperature is reached, heating will stop. The commonly used temperature regulator in laboratories now is a mercury conductivity meter, which is available in the market and easy to use. It can be adjusted and used freely within a large temperature range.
Precautions
(1) Before and after each use, the taper hole of the module must be cleaned with a cotton swab dipped in distilled water to ensure sufficient contact between the test tube and the taper hole wall.
(2) During the process of setting a new temperature, the local system continues to operate according to the last set temperature value until the SV window flashes and the number stops.
(3) If the displayed temperature (PV) differs from the third-party measured temperature by more than 0.1 ℃, contact the local custodian for temperature error correction.
(4) During the use of the thermostat, it is prohibited to press the (calibration/DJ) button.
(5) If the experimental operation is carried out at a constant temperature of 4 ℃ for more than 4 hours, the module condensate must be removed. The method is to unplug the power plug and cut off the power, then unscrew the two black knobs on the module, remove the module, use a soft cloth to clean the condensation water on each contact surface, and then install and reset the module.