What Is an Industrial Constant Temperature Dryer?
An industrial constant temperature dryer is a dryer that maintains a uniform temperature inside the chamber and is used to dry the moisture content of the object to be dried. They are broadly classified into two types: natural convection dryers and forced convection dryers.
In addition to industrial constant temperature dryers, they are also referred to as constant temperature dryers. The temperature inside the chamber is uniformly controlled with high precision, and the high-temperature environment is maintained at a constant level, enabling objects to be dried with efficient heating.
Most of them can be set up to a maximum temperature of 200 to 300°C, and the price is approximately 700 USD and up.
Uses of Industrial Constant Temperature Dryers
As the name suggests, industrial constant temperature dryers are most commonly used to dry objects, such as glassware for experiments and experimental samples. They are also used for degassing and curing samples, and for analysis such as heat resistance testing and moisture measurement under constant temperature conditions.
Among industrial constant temperature dryers, the natural convection type is suitable for drying powdery materials that easily scatter, since the air is circulated by natural convection of heater heat and is less likely to be scattered by the air flow. There are various sizes available, from small ones that can be used on a tabletop to large ones that can be placed on the floor and have a height of over 1 meter.
Principle of Industrial Constant Temperature Dryers
Natural convection constant temperature dryers use the buoyancy created by the generation of heat to create a natural convection current in the gas to equalize the temperature inside the chamber. Heat has energy in proportion to its temperature, and as heat is transferred to the air, the temperature of the air rises.
As the temperature of a substance rises, the movement of its molecules becomes more active, and as the temperature rises, the density of the substance decreases. The difference in density causes buoyancy in the opposite direction to that of gravity, resulting in convection, which is the mechanism of natural convection.
On the other hand, forced convection industrial constant temperature dryers use a fan to circulate the heat from the heater to equalize the temperature inside the chamber. The temperature distribution inside the dryer tends to be more constant than that of a natural convection dryer, and the drying time tends to be shorter than that of a natural convection dryer because of the firm air flow.
How to Select an Industrial Constant Temperature Dryer
There are seven main items to consider when purchasing an industrial constant temperature dryer:
- Size
- Power supply voltage
- Number and height of shelves
- Temperature and temperature control performance that can be set
- Convection system
- With/without timer/program function
- Over-temperature protection device
It is advisable to consider which model to choose based on the need for these features in combination with price. The following is a detailed description of each item.
1. Size
The model you choose will depend on whether you plan to install it on a laboratory table or shelf, or directly on the floor. In addition, since it is a heating device, it is necessary to provide space between the device and adjacent equipment or walls, so choose a size that allows for this.
2. Power Supply Voltage
Smaller models can be used with a 100 V power supply just like ordinary household appliances, but some larger models require a 200 V power supply. Some of them require a 200 V power supply even if they are small, so be sure to check not only the size but also the power supply voltage.
3. Number and Height of Shelves
The more shelves there are, the more space is available in the dryer. On the other hand, the height of each shelf is lower, so you will not be able to put taller utensils or samples in the dryer. Select the appropriate number and height of shelves based on the type of items to be placed in the dryer.
4. Temperature Setting and Temperature Control Performance
Since an industrial constant temperature dryer is a heating device, the lower limit of the temperature that can be set is room temperature. On the other hand, the upper limit of temperature setting can be as high as 200°C or as low as 300°C, depending on the model. The temperature control performance is a value that indicates the degree to which the temperature can be maintained at a constant level within a fluctuating range.
It is described by the notation “±○°C.” The higher the control capability (±○°C), the higher the temperature control capability (±○°C). The higher the control performance (smaller “±○°C” value), the higher the price.
5. Convection Method
As mentioned above, there are natural convection and forced convection types. The natural convection type is better for drying powders and other materials that easily scatter. Since the forced convection type is basically more expensive than the natural convection type, the natural convection type should be selected from an economic standpoint even when rough temperature distribution is sufficient, such as when drying glassware.
On the other hand, when strict temperature control is required, such as in heat resistance testing or moisture analysis, the forced convection type with its superior temperature control capability is preferable. For testing purposes, it is important to check not only the convection method but also the temperature control performance of the device.
6. Availability of Timer/Program Function
If the equipment has a timer function, it can be operated in the form of “turn off the power after ○ hours.” This function is useful when you do not want to apply more heat than necessary, or when you want to avoid running the unit all night long because you forgot to turn off the power.
Those with a program function can be programmed to operate with temperature and time settings, such as “XX hours at XX°C, then XX hours at XX°C,” and so on. The higher performance than the timer function comes at a higher price.
7. Over-Temperature Protection Device
The over-temperature protection function is a function that forcibly turns off the equipment if the temperature rises above the set temperature due to a malfunction in the equipment’s control system. The over-temperature protection temperature can be set separately from the dryer temperature setting.
For example, the dryer temperature and over-temperature protection can be set to 60°C and 100°C, respectively. Many of the dryers on the market today have a built-in over-temperature protection function as a safety feature, but some of the less expensive models do not have such a safety feature.
Since these devices can be set to temperatures as high as 200°C or 300°C, which can cause fires, it is recommended to purchase devices with an over-temperature protection function.