Common faults and solutions of tube furnaces used in university laboratories

During the use of tube furnaces in university laboratories, some common faults may be encountered. The following are some common fault phenomena, possible causes, and corresponding solutions:

1、 No power supply or power indicator light not on
Phenomenon:

After turning on the power switch, the power indicator light of the tube furnace does not light up, or there is no power display on the instrument.
Possible reasons:

The plug is not properly inserted or the power cord is damaged.
The fuse is blown.
The fuse of the control circuit is blown.
resolvent:

Check if the plug is properly inserted and if the power cord is damaged to ensure normal power supply.
Replace the fuse.
Check the control circuit, eliminate the short circuit fault, and replace the fuse.
2、 The temperature inside the furnace does not rise
Phenomenon:

The power supply and heating elements of the tube furnace are normal, but the temperature inside the furnace does not rise.
Possible reasons:

The set temperature is relatively low.
The control circuit is damaged.
Heating element failure or damage.
resolvent:

Adjust the set temperature to ensure that it is higher than the current temperature inside the furnace.
Notify professional maintenance personnel to inspect and control the circuit.
Check the integrity of the heating element and replace it if damaged.
3、 Inaccurate or abnormal temperature display
Phenomenon:

The temperature display of the tube furnace is inaccurate, with deviations from the actual temperature, or there is no display at all.
Possible reasons:

The temperature sensor is damaged or malfunctioning.
The temperature controller is damaged.
There is a deviation between the temperature measurement point and the layout point.
There is dirt or uneven distribution of heating elements inside the furnace.
resolvent:

Use a thermometer and multimeter to test the temperature sensor and confirm if it is damaged. If it is damaged, replace it with a new temperature sensor.
Replace the temperature controller.
Set the layout position correctly to ensure accurate temperature measurement.
Clean the tube furnace, remove the dirt inside the furnace, and check the distribution of heating elements. Adjust if necessary.
4、 During the heating process, the temperature does not rise but instead decreases
Phenomenon:

During the heating process, the temperature of the tube furnace does not increase but decreases.
Possible reasons:

The positive and negative terminals of the thermocouple are reversed.
resolvent:

Swap the positive and negative wiring of the thermocouple.
5、 The ammeter has no current, while the voltmeter has voltage
Phenomenon:

During the heating process, the ammeter does not display current, but the voltmeter displays voltage.
Possible reasons:

The heating element is broken.
resolvent:

Open the furnace door and observe the integrity of the heating element. If there is any breakage, replace the heating element.
6、 Overtemperature alarm
Phenomenon:

The tube furnace emits an over temperature alarm during operation.
Possible reasons:

The set temperature is too high, exceeding the rated temperature of the tube furnace.
The temperature controller (temperature controller) has malfunctioned, resulting in inaccurate temperature control.
resolvent:

Adjust the set temperature to ensure it is within the rated temperature range of the tube furnace.
Replace the temperature controller.
7、 Furnace cracking or furnace tube damage
Phenomenon:

The furnace chamber of the tube furnace cracks or the furnace tubes are damaged.
Possible reasons:

Not preheated after first use or prolonged disuse.
The furnace temperature exceeds the rated temperature, causing damage to the heating elements and furnace lining.
Directly injecting various liquids or dissolving metals into the furnace can cause damage to the furnace.
resolvent:

After the first use or long-term disuse, perform preheating treatment: heat to around 120 ℃ and bake for 1 hour, then heat to around 300 ℃ and bake for 2 hours before use.
The furnace temperature should not exceed the rated temperature as much as possible to avoid damaging the heating elements and furnace lining.
It is prohibited to directly pour various liquids and dissolve metals into the furnace to maintain its cleanliness.
8、 Poor airtightness
Phenomenon:

The tube furnace has poor airtightness when vacuuming or introducing gas.
Possible reasons:

The sealing ring is aging or damaged.
Loose or poorly sealed furnace tube connections.
resolvent:

Check the condition of the sealing ring, and replace it with a new one in a timely manner if it is aged or damaged.
Tighten the furnace tube connection to ensure good sealing.
9、 Uneven heating
Phenomenon:

The sample heating inside the tube furnace is uneven.
Possible reasons:

Improper layout of furnace tubes.
Uneven or damaged distribution of heating elements.
Improper placement of samples.
resolvent:

Adjust the layout of the furnace tubes to ensure even heat distribution.
Check the distribution of heating elements and adjust or replace damaged heating elements if necessary.
Adjust the placement of the sample to ensure even heating.
preventive measure
Regular maintenance: Regularly maintain and upkeep the tube furnace, check the integrity of heating elements, temperature sensors, temperature controllers, and other components, and replace damaged parts in a timely manner.
Standardized operation: Strictly follow the operating procedures of the tube furnace to avoid equipment damage or experimental failure caused by improper operation.
Safe use: When using a tube furnace, pay attention to safety protection measures, such as wearing protective goggles, gloves, etc., to ensure the safety of experimental personnel.
Through the above measures, common faults in tube furnaces can be effectively prevented, and the reliability and service life of the equipment can be improved.