As the core equipment for measuring the thermal conductivity of materials, the stable operation of the thermal conductivity meter is crucial for the reliability of experimental data. The following are common fault diagnosis and daily maintenance guidelines to help users efficiently solve problems and extend equipment life.
Common fault diagnosis
Abnormal temperature control
Performance: Heating wire breakage or temperature control circuit malfunction causing large temperature fluctuations.
Diagnosis: Use a multimeter to check the resistance value of the heating wire and the voltage of the temperature control circuit. If the resistance is abnormal or the voltage is unstable, the heating wire or temperature control component (such as thyristor or thermistor) needs to be replaced.
Case: A laboratory experienced a temperature deviation of ± 5 ℃ due to aging temperature control components. After replacement, the accuracy was restored to ± 0.1 ℃.
Measurement result fluctuation
Performance: Unstable data and poor repeatability.
Diagnosis: Check if the sample processing system is blocked (such as pressure pipes, filter dust accumulation), or if the thermocouple is aging and causing poor contact. When the ambient temperature fluctuates greatly, it is necessary to strengthen temperature control.
Case: A certain enterprise blocked the heat flow meter due to residual impurities in the sample, and after cleaning, the measurement repeatability increased from ± 8% to ± 2%.
Indication error or drift
Performance: Zero point or range deviation, data does not match the standard value.
Diagnosis: Improper calibration operation or deviation in standard gas composition are the main causes. Re calibrate with qualified standard gas and ensure stable sample flow rate.
Case: A research institute failed calibration due to contamination of standard gas cylinders, and the problem was resolved after replacing the cylinders.
Key points of daily maintenance
Cleaning and maintenance
Surface cleaning: Wipe the instrument casing with a soft cloth to avoid the use of corrosive reagents.
Internal cleaning: Clean the holes and hot wires in the thermal conductivity pool after power outages every quarter to prevent dust accumulation from affecting heat conduction.
Key components: Clean the heat transfer disk and thermocouple after each test to prevent residue from interfering with the measurement.
Calibration and Debugging
Regular calibration: At least once a year, use high-precision standard materials (such as standard glass, metal) to verify the zero point and range.
Environmental control: Before calibration, ensure that the ambient temperature is stable, the humidity is below 60%, and stay away from vibration sources and electromagnetic interference.
Operating Specifications
Sample processing: Dehumize the sample before testing to avoid droplet damage to the sensor; During continuous testing, it is necessary to cool down at intervals (for example, silicone rubber needs to be cooled to room temperature for more than half an hour).
Transportation protection: Avoid severe vibration or impact. When not in use for a long time, cover with plastic bags to prevent moisture and preheat for 30 minutes every half month.
Component replacement
Vulnerable parts: Regularly inspect thermocouples, sensors, seals, etc., and replace them promptly if aging or damage is found.
Power cord: Check if the wiring is loose to prevent poor contact from causing faults.
summary
Through systematic troubleshooting (such as temperature control, cleaning and maintenance, calibration operations) and periodic maintenance (such as quarterly cleaning, annual calibration), the sudden failure rate can be reduced by more than 80%, and the service life of equipment can be extended. It is recommended to establish maintenance records, including calibration dates, component replacement situations, and environmental parameters, to form a standardized management system and provide stable and reliable testing support for scientific research and production.