The difference between a thermostatic metal bath and a thermostatic water bath

Both are electric heating technologies, and electric heating incubators are also called ovens and drying ovens. It is a device that uses a heating wire compartment to heat and dry objects. It is used for operations such as constant temperature baking, drying, heat treatment, etc., in the range of room temperature to 300 °C.

Generally, it is composed of three parts: the box, the electric heating system and the automatic constant temperature control system.

1. Internal heating area: The internal heating area refers to the heating area inside the water bath heater, which is a closed space that contains the heater's pipes, heaters, controllers, temperature sensors and other equipment, which together control the change of water bath temperature.

2. External heating area: The external heating area refers to the heating area outside the water bath heater, which is an open space that contains water bath containers, water bath temperature sensors and other equipment, which jointly control the change of water bath temperature.

Thermostatic metal bath (dry thermostatic metal bath) is controlled by microcomputer and uses high-purity aluminum material as a heat conduction medium to replace the traditional water bath device, which has the characteristics of exquisite appearance, easy to use, high precision and small size. It can be widely used in sample preservation and reaction, DNA amplification and electrophoresis pre-denaturation, serum coagulation, etc.

In order to make the temperature of the heat block uniform, high-density aluminum alloy materials need to be used, and the best thing is that the tube is as close as possible to the metal surface to ensure that it is heated evenly to a greater extent.

Water bath heating: The substance to be heated is placed in water, and the effect of heating the substance is achieved by heating the water. Generally, the substance to be reacted is placed in a test tube, and then the test tube is placed in a beaker filled with water, and a thermometer is inserted in the beaker to control the reaction temperature.

The advantage of water bath heating is that it avoids the excessive intensity caused by direct heating and the uncontrollable temperature, and can be heated smoothly, and many reactions require strict temperature control, so water bath heating is required. The disadvantage of water bath heating is that the heating temperature can only reach a maximum of 100 degrees.

Water bath constant temperature: Water bath constant temperature is to maintain the substance at a certain temperature (first of all, the initial temperature of the object must be changed to the temperature of the water bath, which may be from low to high, or from high to low).

Generally speaking, water bath heating is suitable for chemical reactions such as Feilin reagent that do not have a very strict temperature control (50 60), while water bath constant temperature is generally used for delicate problems such as the optimal temperature for the activity of enzymes. The difference between the two concepts is not very obvious in high school, and the difference between the two is generally ignored, and the two can generally be substituted for each other.

Water bath heating is to change the substance from low temperature to high temperature.

The constant temperature of the water bath is to maintain the substance at a certain temperature (first of all, the initial temperature of the object must be changed to the temperature of the water bath, which may be from low to high, or from high to low).

The working principle of a thermostatic water bath is briefly described as follows: The bath consists of a container and a liquid medium. If the temperature required to be set is not much different from the room temperature, a 20dm3 round glass tank can usually be used as a container.

If the set temperature is high (or low), the entire tank should be insulated to reduce the heat transfer speed and improve the accuracy of constant temperature.

The thermostatic water bath uses distilled water as the working medium. If the device is slightly modified and other suitable liquids are used as the working medium, the above-mentioned thermostatic bath can be used in a wide range of temperatures. In cases where the set temperature is required to be higher than the room temperature, a continuous supply of heat must be provided to compensate for the heat lost to the environment by the bath.

The selection principle of electric heater is small heat capacity, good thermal conductivity and appropriate power. If the bath with a capacity of 20dm3 requires a constant temperature between 20 30, an electric heater of 200 300W can be used. When the room temperature is too low, a higher power or two sets of heaters should be used.

Mercury contact thermometer. Mercury contact thermometers are also known as mercury conductivity meters.

The upper part of the mercury ball is welded with a metal wire, and the upper part of the thermometer has another metal wire, both of which are connected to the signal feedback end of the relay through the lead wire. The top of the contact thermometer has a magnetic spiral adjustment cap to adjust the height of the wire contacts. At the same time, the approximate temperature control setting temperature can be estimated by adjusting the position of the indicator nut on the ruler from the thermometer.

When the temperature of the bath rises, the mercury expands and rises to the contact, the coil in the relay is energized to generate a magnetic field, the spring sheet of the ** circuit jumps open, and the heater stops heating. Then the heat of the bath spreads outward, causing the temperature to drop, the mercury shrinks and detaches from the contacts, the electromagnetic effect of the relay disappears, the spring springs back, and the heater circuit is turned on, and the system temperature begins to rise again. This contact thermometer works repeatedly.

And the system temperature is controlled. It can be said that it is the center of the thermostatic bath and plays a key role in the thermostat. The relay must be connected to the heater and contact thermometer in order to function as temperature control.

Relays commonly used in laboratories are tube relays and transistor relays.

To measure the quality of a thermostatic water bath, it can be measured by the sensitivity of the thermostatic water bath. Sensitivity is usually expressed as half the difference between the highest and lowest temperature values measured.

Since dry constant temperature metal baths are more common on the market and have different parameters, we take two instruments produced by Shanghai Broadcom Chemical Technology as an example.

Dry thermostatic metal bath parameters.

1. Real-time temperature and countdown display.

2. Automatic fault detection and buzzer alarm function.

3. Temperature deviation calibration function.

4. Built-in over-temperature protection device.

5. Convenient module replacement, easy to clean and disinfect.

6. The appearance is exquisite, and the blue LCD displays real-time parameter information.

7. Optional power-off automatic recovery function, start-up automatic operation function, improve work efficiency.

8. The intelligent algorithm ensures the accuracy of temperature control in the whole process and effectively reduces the experimental error.

9. Multiple safety protections to ensure the stability of long-term operation and safety in unattended situations, in line with CE standards.

10. The module can be customized according to customer requirements.

Data sheet overview

Dry heaters are available in three sizes: single module, double module and four modules, suitable for a wide range of temperature control, the maximum temperature can reach 150, with good uniformity, widely used in molecular biology, clinical, archaeology, environmental and other industries.

The instrument is controlled by a digital microprocessor and a high-power heater provides precise and accurate heating, and the stainless steel module ensures that the heater can uniformly transfer heat to all holes; There are a variety of different types of heating modules to choose from, different types of modules are suitable for tubes without aperture diameter, and solid modules are also available; In addition, each dry heater is equipped with a lifting rod to facilitate the operator to replace the module, and the module can also be lifted and replaced in a hot state, reducing the waiting time for cooling.

features

The wide temperature range with a maximum value of 150 °C and the metal modules have very good thermal homogeneity.

The metal module ensures that the heater can transfer heat uniformly to the various holes.

A digital microprocessor controls a high-wattage heater to provide precise, accurate temperatures.

A variety of pore size modules are available, ranging from PCR tubes to 50 ml centrifuge tubes and 96-well plates.

It is equipped with a lifting lever to facilitate the operator to replace the module, and the module can also be lifted and replaced in a hot state, reducing the waiting time for cooling.

Suzhou Hisiyuan.