The following are the key points for periodic maintenance of aerosol photometers:

1. Daily basic maintenance

Cleaning and Calibration of Optical Components

Use a dry and dust-free cloth or specialized lens paper to gently wipe the surface of the light source lens, scattering chamber, and photodetector to avoid fingerprint oil stains affecting the transmittance. If stubborn stains are found, a small amount of anhydrous ethanol can be soaked in a cotton swab and gently wiped, then immediately absorb the residual liquid with a dry cloth. Special attention should be paid not to scratch the coated lenses to prevent coating detachment and optical path deviation.

Regularly check the working status of the laser diode and observe whether the beam intensity is stable. For lasers with significant attenuation, it is necessary to adjust the power supply parameters or replace aging components in a timely manner to ensure the accuracy of the scattered light signal.

Integrity testing of pneumatic system

Before starting up daily, confirm that the sampling pipeline is tightly connected and leak free. The sealing can be verified by manually blocking the air inlet and observing changes in the pressure gauge. Focus on inspecting loose parts such as quick connectors and filter brackets, and if necessary, re tighten screws or replace aging sealing rings.

Clean up the large particles intercepted by the coarse filter to prevent blockage and flow imbalance. For high-precision HEPA filters, it is recommended to use compressed air to blow in reverse every week to remove dust and restore ventilation efficiency.

Sensor performance verification

Use standard latex ball suspension for zero and range calibration, record instrument response values and compare them with theoretical curves. If there is a systematic deviation, it is necessary to re-enter the correction factor or adjust the gain knob. Simultaneously test the linear correlation under different concentration gradients to ensure measurement reliability within the dynamic range.

Monitor the impact of environmental temperature and humidity fluctuations on readings, increase parallel test frequency under extreme conditions, and establish compensation algorithms to correct data drift.

2. Monthly deep maintenance of aerosol photometer

Disassembly and maintenance of core components

Dismantle the scattering chamber module and remove the particulate matter deposited inside. Use a soft bristled brush to sweep away the accumulated dust in the corners, and then aim a nitrogen cylinder at the narrow slit area to blow away residual debris. Check if the sheath gas nozzle is deformed. If there is any deformation, replace the spare parts to ensure laminar flow stability.

Lubricate mechanical transmission components (such as stepper motor gear sets) and use low volatility silicon-based grease to reduce wear and noise. When the tension of the synchronous belt is insufficient, adjust the position of the eccentric wheel according to the instructions to avoid positioning errors caused by belt slippage.

Electrical safety inspection

Measure the insulation resistance of the power cord and check for oxidation and discoloration of the wiring terminals. For equipment used in humid environments, moisture-proof covers can be installed and condensation droplets on the circuit board can be dried regularly. Test the effectiveness of the emergency stop button function to ensure that it can instantly cut off the high-voltage power supply circuit in case of emergencies.

Backup the current firmware version information, upgrade the latest patch program through official software tools, fix potential vulnerabilities, and optimize algorithm models.

Fluid circuit purification treatment

Drain the distilled water from the storage tank and add fresh ultrapure water to circulate and rinse the entire liquid system at least three times. Replace the aged and discolored silicone tubing to prevent secondary pollution caused by swelling and rupture. During the cleaning process, pay attention to observing whether the waste liquid discharge is smooth, and promptly clear the impurities in the drainage valve filter screen.

Calibrate the matching between the rotational speed of the peristaltic pump and the actual flow rate, and verify the accuracy of the liquid volume delivered per unit time using the weighing method. If the error exceeds the allowable range, the motor pulse parameters need to be reset.

3. Quarterly comprehensive testing of aerosol photometer

Cross module linkage testing

Simulate continuous monitoring scenarios under real working conditions to test the long-term stability of the data acquisition system. Set up multiple sets of standard substances with different particle size distributions for alternate injection to verify the response speed and repeatability of the instrument when automatically switching ranges. Pay close attention to the smoothness of the transition between high and low concentrations to avoid false alarms caused by jumping.

Test the compatibility of the communication interface, connect the device to the upper computer control system, and check the instruction transmission delay time and data transmission integrity rate. Synchronize triggering external trigger signals to verify the timeliness of the synchronous recording function.

Verification of the effectiveness of protective devices

Artificially creating slight overload conditions (such as temporarily blocking the laser beam), verify whether the safety interlock mechanism can activate the protection program normally. Test the operating status of the equipment with the dust cover closed and confirm the sensitivity and reliability of the cut-off switch.

Check the integrity of the radiation shielding material, use a Geiger counter to scan the seams of the casing for any leakage, and promptly repair areas with insufficient lead equivalent.

Historical data traceability analysis

Export quality control records from the past three months, draw trend charts to identify abnormal fluctuation cycles. Conduct correlation analysis based on laboratory temperature and humidity logs, power supply voltage fluctuation curves, and other factors to locate potential sources of interference. Perform retesting and comparison on suspicious data segments to eliminate accidental error factors.

Adjust the automatic alarm threshold range based on statistical analysis results and optimize the balance point between warning sensitivity and false alarm rate.

4. Annual overhaul plan for aerosol photometer

Whole machine performance restoration project

Replace all consumable components such as xenon flash tubes and photomultiplier tubes, and re calibrate the optical alignment system according to factory specifications. Use an interferometer to calibrate the optical path collimation, ensuring that the laser beam is fully focused on the center point of the detection plane.

Disassemble and clean the entire aerosol generation device, replace the severely worn ultrasonic transducer chip, and restore the atomization efficiency to its initial level. Re calibrate the gas conversion factor of the mass flowmeter and correct the measurement deviation caused by sensor aging.

Environmental adaptability transformation and upgrading

According to the annual fault statistics report, strengthen the redundancy design of weak links in a targeted manner. For example, adding shock-absorbing washers in vibration sensitive areas and installing magnetic shielding covers in places with severe electromagnetic interference. Evaluate the effectiveness of existing cooling solutions and, if necessary, increase the fan speed range or modify the liquid cooled cooling module.

Update the preventive maintenance checklist in the operation manual, include frequent unplanned downtime events as key monitoring items, and develop special improvement measures.