Box-type resistance furnaces are a common type of electric furnace and are widely used in various industries, including ceramics, metallurgy, electronics, glass manufacturing, chemical processing, and mechanical engineering. During operation, when the furnace temperature rises above 200°C, the significant temperature difference between the inside and outside of the furnace can cause damage to the furnace lining and heating elements if the door is opened at this time for rapid cooling. Therefore, to protect the equipment and ensure safety, it is stipulated that the furnace door must not be opened for rapid cooling when the temperature exceeds 200°C. When using a box-type resistance furnace, the following precautions should be observed to ensure safe operation and proper equipment performance:

I. Pre-Operation Preparation

1. Equipment Inspection: Prior to operation, first inspect the enclosure of the box-type resistance furnace to ensure it is intact, and check the power cord, controller, and interior of the furnace chamber for any damage or foreign objects. Ensure that the furnace door is properly sealed.
2. Wear protective equipment: Before commencing operations, be sure to don work uniforms, heat-resistant gloves, safety goggles, and other protective gear to prevent burns from high temperatures.
3. Clean the work area: Do not place flammable or explosive materials around the resistance furnace, and ensure adequate ventilation.

II. Operating Procedure

1. Preheating Preparation: Based on experimental or production requirements, set the appropriate heating temperature and holding time, and preheat the resistance furnace to a temperature within a specified range below the set point to minimize thermal shock.
2. Placement of Samples: Use a dedicated crucible or container to gently place the sample to be heated inside the furnace chamber, taking care to prevent contact between samples to avoid contamination and uneven heat distribution.
3. Starting the Equipment: After confirming that all settings are correct, connect the power supply and press the start button or initiate the heating program via the controller.
4. Temperature Monitoring: During the heating process, closely monitor the temperature changes displayed on the temperature controller to ensure that the furnace temperature rises according to the preset heating curve. If any abnormalities are detected, make timely adjustments or shut down the equipment for inspection.
5. Avoid opening the door during operation: When the high-temperature box-type resistance furnace is operating above 300°C, it is not recommended to open the door to prevent scalding from hot air jets or sudden temperature drops that could compromise heating performance. If it is absolutely necessary to open the door, wait until the furnace temperature has cooled to a safe level (e.g., below 200°C) before carefully opening the door.

III. Post-Operative Management

1. Remove the sample: After the furnace temperature has cooled to a safe range, carefully remove the sample using dedicated tools to prevent burns.
2. Cleaning and Maintenance: Turn off the power, clean the interior of the furnace chamber to remove any residue, and keep the chamber clean and tidy. Inspect the furnace door seal to ensure safe operation next time.

IV. Other Notes

1. Safe Electrical Use: Both the electric furnace and the temperature controller must be reliably grounded to prevent electric leakage and subsequent electric shock accidents.
2. Avoid overheating: During operation, never exceed the maximum operating temperature of the resistance furnace; in general, the temperature should not exceed 500°C to prevent equipment damage or safety incidents.
3. Safety during sample loading and unloading: Always disconnect the power supply before loading or unloading samples to prevent electric shock; minimize the duration that the furnace door is open during these operations to extend the service life of the electric furnace.
4. Prohibition of Liquid Injection: It is prohibited to inject any liquids or molten metals into the furnace chamber to prevent hazards such as explosions.
5. Adhere to Operating Procedures: Do not operate the resistance furnace without permission from management personnel, and strictly follow the equipment’s operating procedures.

In summary, when operating a box-type resistance furnace, it is essential to observe electrical safety precautions, set temperatures appropriately, avoid opening the furnace door during operation, perform timely cleaning and maintenance, and adhere to other relevant safety guidelines, in order to ensure safe operation and proper equipment performance.

After the temperature of the box-type resistance furnace has risen above 200°C, the furnace door must not be opened for rapid cooling, to prevent damage to the furnace lining and heating elements. ‌

In addition, when operating a high-temperature box-type resistance furnace, it is essential to ensure that the furnace chamber temperature does not exceed the rated temperature and that the furnace is not operated at or above the rated temperature for extended periods. Furthermore, the introduction of any liquids into the furnace chamber is strictly prohibited; samples contaminated with water or oil must not be placed in the furnace chamber, nor should samples be handled or removed using tongs or other tools that are wet or oily.