As the core component of precision analytical instruments, the performance status of the airtight injection needle directly affects the accuracy of experimental data and the service life of the instrument. Scientific maintenance management can not only maintain the airtightness of the system, but also significantly reduce the failure rate and ensure the smooth progress of the experimental process. The following provides a multidimensional analysis of the key points of professional maintenance.
1、 Standardized daily cleaning operations
After each use, the basic cleaning procedure should be performed immediately. Using a specialized cleaning kit, perform gradient rinsing with neutral detergent solution, ultrapure water, and anhydrous ethanol in sequence, focusing on removing trace residues inside the needle body and at the conical interface. For lipid soluble substance contamination, acetone or n-hexane can be used for deep degreasing. Special attention should be paid not to touch the inclined surface of the needle tip to prevent physical damage from damaging the surface smoothness. After cleaning, it should be placed in a constant temperature oven for low-temperature drying (≤ 80 ℃) to avoid metal deformation caused by high temperature.
2、 Special maintenance of key parts
The injection pad is a consumable material that is easily damaged. It is recommended to replace it with a new pad every 50 puncture operations. During installation, the nuts should be evenly tightened to maintain a moderate compression of the spacer. PTFE sealing rings need to be regularly checked for aging, and if hardening or cracking occurs, they should be replaced in a timely manner. For moving parts, apply an appropriate amount of silicon-based lubricant to the valve stem guide mechanism every month, taking care to avoid grease contamination of the flow path. The electronically controlled pneumatic sampler also needs to check the sensitivity of the solenoid valve and adjust the position of the travel switch if necessary.
3、 Construction of airtightness testing system
Establish a three-level testing system: conduct a simple bubble method test before starting up each day, immerse the needle in water and apply pressure to observe whether there are continuous bubbles generated; Use a dedicated leak detector for quantitative testing every week to ensure that the leakage rate is below the allowable value of the instrument; Quarterly pressure attenuation testing can comprehensively evaluate the sealing performance of the system. When a decrease in air tightness is found, each connecting part should be checked step by step, with a focus on checking the compression strength of the sleeve joint and the degree of pipeline aging.
4、 Standardized usage guidelines
Strictly follow the principle of "three checks": check the smoothness of the pipeline before plugging and unplugging, check the concentricity deviation during clamping, and check for pressure fluctuations during operation. It is prohibited to disassemble and assemble under pressure. When switching samples, the residual pressure in the system should be drained. Manual injection should be carried out at a constant speed to avoid sudden acceleration causing impact damage. Mixing adapters with different specifications of injection needles is strictly prohibited to prevent chronic leakage caused by excessive fitting tolerances.
5、 Refined management of storage environment
Unused spare parts should be stored in a dryer with a relative humidity controlled below 30%. Long term idle injection needles need to be coated with rust proof oil for protection, especially nickel plated parts, which should pay attention to oxidation prevention. Regularly power on and test the function of the solenoid valve during storage to prevent spring failure. During the transportation process, specialized shock-absorbing packaging must be used to avoid severe vibrations that may cause precise misalignment.
Implementing a preventive maintenance plan is key to extending the lifespan of injection needles. It is recommended to establish equipment archives to record the maintenance time, replacement parts model, and testing data for each maintenance. When there is an abnormal injection volume or peak broadening, priority should be given to the airtightness of the injection system. Through systematic scientific maintenance, the injection needle can maintain stable airtightness, providing reliable assurance for trace analysis and repetitive experiments.