Precautions for operating customized experimental muffle furnace

Customized experimental muffle furnaces require strict adherence to specifications during operation due to complex configurations such as vacuum, atmosphere control, high temperature, etc., to ensure experimental safety, accurate data, and extend equipment lifespan.

1. Preparation before the experiment
Environmental inspection
Ventilation conditions: Ensure good ventilation in the laboratory and avoid the accumulation of high temperatures or toxic gases (such as gases produced by hydrogen reduction reactions).
Power stability: Use independent power sockets to avoid sharing power lines with other high-power devices and prevent voltage fluctuations from damaging the equipment.
Equipment grounding: Check whether the grounding wire of the furnace body is firm to prevent electric shock accidents caused by leakage.
Sample pretreatment
Drying treatment: Samples containing volatile components (such as moisture and organic solvents) need to be dried in advance to avoid releasing gases during vacuum pumping that can contaminate the vacuum system or cause sample splashing.
Fixed and packaged: Powder samples need to be compacted or packaged in crucibles to prevent them from being evacuated by vacuum pumps; Fragile samples need to be fixed with high-temperature resistant brackets to avoid tipping during the heating process.
Equipment status confirmation
Sealing inspection: Check whether the sealing rings of the furnace door, observation window, gas interface and other parts are intact, without aging or damage.
Vacuum pump oil level: If vacuum pumping is required, confirm that the mechanical pump oil level is at 1/2-2/3 of the oil window, and the oil quality is clear without emulsification.
Gas pipeline: Check whether the connections of hydrogen, nitrogen and other gas pipelines are firm and leak free (soap water can be applied to the interface to observe bubbles).

2. Standard operating procedures
Heating and temperature control
Segmented heating: Set up multiple program heating stages based on the characteristics of the sample (such as raising from 50 ℃/min to 300 ℃, holding for 30 minutes, and then raising to the target temperature at 10 ℃/min) to avoid rapid heating that may cause sample cracking or equipment overload.
Temperature calibration: When first used or not used for a long time, use a standard thermometer to calibrate the deviation between the actual temperature inside the furnace and the displayed value (usually ≤± 5 ℃ is qualified).
Overtemperature protection: Confirm that the overtemperature alarm device is activated and the set temperature is 20-50 ℃ lower than the target temperature to prevent accidents caused by temperature control failure.
Vacuum and Atmosphere Control
Vacuum extraction steps:
Close the furnace door and lock it tightly, confirming that there are no foreign objects in the sealing ring;
Start the vacuum pump and slowly open the valve to pump air to the target vacuum level (to avoid splashing the sample due to rapid pumping);
During the vacuuming process, observe the reading of the vacuum gauge. If it cannot reach the set value for a long time, stop the machine and check for leaks.
Inflating operation:
Close the vacuum pump valve first, and then slowly introduce gas to atmospheric pressure (to avoid damage to the furnace caused by sudden pressure changes);
If a mixed atmosphere (such as 5% hydrogen+95% nitrogen) is required, the gas ratio must be accurately controlled through a mass flow meter.
Atmosphere circulation: For experiments that require maintaining an atmosphere for a long time, regularly check the gas flow rate to prevent pipeline blockage or leakage.
Furnace door opening and closing
Cooling requirement: After the temperature inside the furnace drops to ≤ 200 ℃, open the furnace door to prevent high-temperature burns or cracking of the furnace due to rapid cooling.
Emergency situation: If you need to open the furnace door halfway, you must first cut off the power, close the gas valve, and wear insulated gloves and protective face shields.

3. Safety protection measures
Personal protective equipment
High temperature resistant gloves: Wear them when operating the furnace door or taking and placing samples to prevent burns.
Protective face mask: Avoid damage to the face from high temperature splashes.
Gas mask: Used when handling toxic samples (such as sulfur and phosphorus compounds) to prevent inhalation of harmful gases.
Experimental clothing and goggles: Wear them throughout the entire process to prevent chemical reagents or high-temperature particles from coming into contact with the skin or eyes.
Equipment safety device
Access control interlock: Ensure automatic power-off when the furnace door is opened to prevent accidents caused by misoperation.
Hydrogen concentration monitoring: If hydrogen is used, a hydrogen leak alarm must be equipped. When the concentration exceeds the limit, the gas source will be automatically cut off and the exhaust system will be activated.
Emergency stop button: Familiarize yourself with the location of the emergency stop button and immediately press it in case of unexpected situations (such as abnormal equipment noise or smoke).
Emergency Response Plan
Fire response: When a fire breaks out in the furnace, immediately cut off the power, close the gas valve, and use a carbon dioxide fire extinguisher to extinguish the fire (water is strictly prohibited).
Vacuum pump malfunction: If there is abnormal vibration or increased noise in the pump body during the vacuum pumping process, immediately stop the machine to check the oil level or replace the pump oil.
Gas leakage: When a gas pipeline leak is found, quickly close the gas source main valve, open doors and windows for ventilation, and contact professional personnel for repair.

4. Maintenance and upkeep
Daily cleaning
Furnace cleaning: After each experiment, use a soft bristled brush to remove any residue in the furnace to avoid volatilization and contamination of the sample at high temperatures.
Observation window cleaning: Use a dust-free cloth dipped in alcohol to wipe the quartz observation window and maintain its transparency.
External dust removal: Regularly wipe the surface dust of the furnace body with a dry cloth to prevent dust accumulation from affecting heat dissipation.
Regular maintenance
Heating element inspection: Check whether the silicon carbon rod/silicon molybdenum rod is aging every 3-6 months (if the resistance value changes by more than 10%, it needs to be replaced).
Sealing ring replacement: Replace the sealing rings of furnace doors, observation windows, and other parts every 1-2 years to prevent vacuum leakage.
Vacuum pump maintenance: Replace the mechanical pump oil every 500 hours, clean the oil circuit filter, and ensure stable vacuum degree.
Long term disuse treatment
Power outage and gas cut-off: Turn off the power supply and gas main valve of the equipment, and exhaust the gas inside the furnace.
Moisture prevention measures: Place desiccants in the furnace and cover the equipment with dust covers to prevent moisture or dust from entering.
Regular power on: When not in use for a long time, power on 1-2 times a month (30 minutes each time) to dispel internal moisture and avoid damage to electronic components.