Troubleshooting of High Temperature Graphite Vacuum Furnace

The possible faults and troubleshooting methods during the operation of high-temperature graphite vacuum furnace are as follows:

1. Abnormal temperature
Unstable temperature or inability to reach the set value
Possible causes: heating element failure (such as burning or breakage), temperature sensor malfunction, control system issues, poor or damaged thermocouple contact.
Exclusion method:
Check the connection and resistance of the heating element, repair or replace damaged heating elements.
Check if the temperature sensor and thermocouple are damaged or poorly connected, replace or reconnect the sensors.
Restart the temperature controller, check if the parameter settings are correct, and calibrate the temperature control system.
Check the resistance of the output terminal of the solid-state relay. If it is broken down, replace it with a new relay.
High temperature alarm
Possible reasons: incorrect temperature controller parameter settings, continuous power on of heating elements, cooling system malfunction.
Exclusion method:
Check if the temperature controller parameters are normal, and refer to other normal equipment to calibrate the parameters.
Check if the heating element is continuously powered on and test if the wires connected to the heating tube in the corresponding work area are energized.
Check if the cooling water pipeline is unobstructed, ensure sufficient cooling water supply, and clean up blockages.

2. Insufficient vacuum degree
vacuum pump failure
Possible reasons: Abnormal operation of the vacuum pump, insufficient power supply, and expansion of mechanical components leading to insufficient clearance.
Exclusion method:
Check the operation of the vacuum pump, clean or replace damaged vacuum pump parts.
Ensure normal power supply and strengthen pump cooling.
Aging or damage of vacuum seals
Possible reasons: Long term aging of seals and improper installation leading to poor sealing.
Exclusion method:
Check and replace aging seals, reinstall seals to ensure sealing effectiveness.
Check if the door is tightly closed and if the sealing film at the entrance is damaged or deformed.
leak
Possible reasons: There may be leaks at locations such as pipelines, pneumatic valves, and thermocouple entrances.
Exclusion method:
Use a vacuum leak detector or other methods to inspect and repair the leak points.
Pay special attention to the inlet of the thermocouple. If the thermocouple is replaced, it may damage the vacuum sealing performance and needs to be re sealed with AB glue.

3. Power and circuit faults
power failure
Possible reasons: poor contact of power plug, broken or worn power cord, abnormal power output.
Exclusion method:
Check if the power plug is in good contact and if the power cord is broken or worn.
Use a multimeter or other tools to check if the power output is normal, replace the plug or power cord in a timely manner, or repair the power supply.
circuit fault
Possible reasons: Relay malfunction, controller setting error, circuit component burnout.
Exclusion method:
Check if the relay is working properly and replace the faulty relay.
Check the settings of the controller to ensure that the parameter settings are correct.
Check the circuit one by one according to the circuit diagram, identify the electrical cut-off point, and replace the burnt out components.

4. Mechanical structural failure
The door doesn’t close tightly
Possible reasons: Loose hinges, deformed buckles, damaged sealing strips at the door entrance, or deformed door panels.
Exclusion method:
Check and tighten the hinges of the door, adjust or replace any deformed buckles.
Replace damaged sealing strips, repair or replace deformed door panels.
Fan abnormal noise
Possible reasons: There are foreign objects inside the fan wheel and loose screws fixing the motor.
Exclusion method:
Clean the foreign objects inside the fan wheel and tighten the screws that fix the motor.
Pneumatic valve cannot operate
Possible reasons: malfunction of solenoid valve, insufficient compressed air pressure.
Exclusion method:
Check if the solenoid valve is working properly and replace the faulty solenoid valve.
Adjust the compressed air pressure to the normal operating range.

5. Other faults
Cooling system malfunction
Possible reasons: Insufficient cooling water supply, blocked cooling system.
Exclusion method:
Check if the cooling water pipeline is unobstructed to ensure sufficient cooling water supply.
Clean the blockage in the cooling system, such as scale, impurities, etc.
Improper sample handling
Possible reasons: The sample was not pre processed and placed in an improper position.
Exclusion method:
Ensure that the sample has been pre treated, dried, and free of impurities such as dust.
Place the sample inside the graphite boat and ensure a tight contact between the graphite boat and the sample.