As a key pre-treatment equipment in environmental monitoring, food safety and other fields, the stability of the blowdown and capture device directly affects the detection accuracy. The following is an analysis and solution for typical faults:

1、 Abnormal airflow fault

Phenomenon: Fluctuations or zeroing of carrier/auxiliary gas flow rate

Possible reasons:

Blockage of gas path: Accumulation of particulate matter or condensation water ice blockage in the injection pipeline;

Electromagnetic valve failure: Long term high-frequency operation leads to wear of the sealing ring;

Quality flow meter malfunction: poor signal line contact or sensor moisture.

Solution:

Segmented inspection of gas path: Starting from the outlet of the steel cylinder, dismantle the pipeline step by step and clean it with anhydrous ethanol ultrasonic cleaning;

Test the on-off function of the solenoid valve and replace the worn PTFE sealing gasket;

Restart the MFC controller, and if it fails, replace it with a flow meter of the same model.

2、 Temperature control system failure

Phenomenon: Abnormal heating rate of the cold trap or inability to reach the set temperature

Core incentives:

Overload of refrigeration unit: Dust accumulation on the cooling fan leads to a decrease in refrigeration efficiency;

Heating block aging: temperature control deviation caused by changes in the resistance value of the heating wire;

PID parameter drift: After long-term operation, the temperature control curve needs to be recalibrated.

Disposal plan:

Clean the dust on the condenser fins and replace the silicone grease if necessary to reduce thermal resistance;

Use a multimeter to check the resistance of the heating module and replace it with a heating rod that matches the specifications;

Enter calibration mode and reset PID parameters using a standard thermometer.

3、 Leakage and cross contamination

Features: Increased baseline noise or target peak appearing in blank samples

Root tracing:

Loose joints: The chromatographic column interface and capture tube flange are not tightened;

Seal damage: O-ring cracking or elastic failure;

Stain residue: High concentration sample residue leads to memory effect.

Repair strategy:

Gradually tighten all connecting nuts in diagonal order;

Replace with high temperature resistant fluororubber O-ring (recommended Viton material);

Execute high-temperature baking program (≥ 280 ℃), combined with inert gas backwash cleaning.

4、 Software communication malfunction

Performance: The computer cannot recognize the instrument or the control command is unresponsive

Technical investigation:

Poor contact of USB/RS232 interface: Re plug and unplug the communication cable;

Driver conflict: Uninstall the old driver and install the latest version of GC control software;

Insufficient operating system permissions: Run control programs as an administrator.

Emergency response: Reset the instrument communication protocol and restore the factory default settings.

5、 Mechanical motion stuck

Symptom: Improper switching of rotary valve or abnormal motor noise

Root cause:

Wear of transmission gears: Long term high load operation can cause excessive clearance between teeth;

Dry lubricating grease: The ball screw lacks necessary lubrication;

Synchronous belt slack: Insufficient belt tension causes slippage.

Repair method:

Replace the wear-resistant alloy gear set;

Inject an appropriate amount of high and low temperature lubricating grease (such as Krytox);

Adjust the tensioning wheel to maintain appropriate tension on the synchronous belt.

Preventive maintenance recommendations

Conduct monthly air pressure maintenance tests (close the outlet to observe pressure decay);

Replace the packing and dewatering membrane of the capture pipe every quarter;

Establish a consumables replacement file and record the service life of filters at all levels;

Regularly conduct no-load operation self checks to verify the timing of valve body actions.

Through systematic investigation and standardized maintenance, equipment reliability can be effectively improved, ensuring the accuracy of trace analysis results. For complex faults, it is recommended to contact the original factory engineer for in-depth diagnosis.