Precautions for using a lifting bell jar furnace

As a high-temperature heat treatment equipment, the safe and efficient operation of the lifting bell jar furnace relies on standardized daily operation and maintenance. The following are key precautions during use, covering four aspects: safe operation, equipment maintenance, process control, and emergency response:

1. Safety operation standards
Personnel protection and operation qualifications
Protective equipment: Wear heat-resistant gloves, protective face shields, and heat-resistant shoes during operation to avoid direct contact with high-temperature furnace bodies or samples.
Qualification requirements: Operators must undergo professional training, be familiar with equipment structure, process flow, and emergency plans, and are prohibited from working without certification.
High temperature environment safety
Furnace temperature limit: When the furnace temperature is ≥ 200 ℃, it is strictly prohibited to open the furnace door or touch the furnace body to prevent burns.
Sample placement: Before loading into the furnace, it is necessary to confirm that the sample size matches the furnace opening to avoid jamming or tilting; Large samples (such as ceramic discs with a diameter>300mm) need to be fixed using specialized fixtures.
Gas usage safety
Ventilation sequence: First evacuate to the target pressure (such as below 5Pa), then introduce protective gases (such as nitrogen and argon) to avoid gas mixing and explosion.
Concentration monitoring: When using combustible gases (such as hydrogen), a concentration alarm device should be installed to ensure that the concentration is below the lower explosive limit.
Waste gas treatment: Waste gas needs to be discharged through dedicated pipelines and is prohibited from being directly discharged indoors to prevent the accumulation of toxic gases.
Vacuum operation specifications
Pressure limit: The pressure inside the furnace tube shall not exceed 0.02MPa (absolute pressure) to avoid equipment damage.
High temperature vacuum taboo: When the temperature of the furnace body is above 1000 ℃, the furnace tube should be kept in a normal pressure state and should not be in a vacuum state to prevent deformation or rupture of the furnace tube.

2. Key points of equipment maintenance
routine inspection
Electrical system: Check if the power cord, plug, and fuse are intact, and confirm that the touch screen display is normal.
Mechanical components: Check if the lifting chain, gears, and motor are adequately lubricated, without any abnormal noise or jamming.
Sealing: Check if there is any air leakage around the furnace door sealing strip, pipeline valves, and kiln car, and replace aging components in a timely manner.
regular maintenance
Heating element: Check the resistance value of silicon carbon rod/silicon molybdenum rod every 500 hours, and replace it if the deviation exceeds 10%.
Thermocouple: Calibrate every 1000 hours to ensure temperature measurement accuracy within ± 1 ℃.
Circulating fan: Replace the graphite packing every 2000 hours and check if the motor shaft is deformed.
Cleaning and anti-corrosion
Furnace cleaning: Remove residues after each use to prevent corrosion of the furnace lining (such as alumina fibers).
External rust prevention: Regularly wipe the surface of the furnace body, apply rust proof paint, and avoid rusting of metal parts in humid environments.

3. Key to process control
temperature control
Heating curve: Set segmented heating programs (such as preheating, insulation, and cooling) based on material characteristics to avoid sample cracking caused by thermal stress.
Temperature uniformity: Use a back mirror or observation window to confirm the uniformity of the temperature field. If the deviation exceeds ± 5 ℃, adjust the position of the thermocouple or the power of the heating element.
atmosphere control
Gas purity: The purity of the protective gas should be greater than the specified value to prevent impurities from contaminating the sample.
Flow regulation: Accurately control gas flow according to process requirements to avoid pressure fluctuations in the furnace caused by excessive flow.
Sample processing
Pre treatment: Metal samples need to undergo pre-treatment such as acid washing and polishing to remove surface oil stains and oxides.
Furnace loading method: The sample spacing should be ≥ 50mm to ensure smooth airflow circulation and avoid local overheating.

4. Emergency response measures
Over-temperature alarm
Immediate response: Press the emergency stop button to cut off the heating power supply.
Cause investigation: Check if the thermocouple is disconnected, if the PID parameters are out of balance, or if the heating element is short circuited.
gas leak
Emergency ventilation: Turn on the exhaust system and evacuate personnel quickly.
Turn off the gas source: Close the valve of the leaking pipeline and use soapy water to detect the leak point.
Lifting malfunction
Manual operation: If the motor is overloaded, switch to manual mode and slowly lift the kiln car.
Travel reset: Adjust the position of the travel switch to ensure that the kiln car is lifted and lowered properly.
fire fighting
Fire extinguishing equipment: equipped with carbon dioxide fire extinguishers, water-based fire extinguishers are prohibited.
Alarm process: Immediately dial 119 and notify the device administrator.