As a key equipment for simulating oceanic climate and detecting product corrosion resistance, the stability of the salt spray test chamber directly affects the accuracy of test data. In the process of long-term use, uneven spray and inaccurate temperature are the two most common faults, which will not only lead to distortion of test results, but also may delay the progress of product development or quality inspection. This article will deeply analyze the causes of these two major faults, provide systematic troubleshooting ideas and practical solutions.
1、 Uneven spray fault: full process troubleshooting from "source to outlet"
The uneven spray is mainly manifested by the large difference in the salt fog deposition in different areas of the test chamber, the absence of salt fog coverage in some areas or the excessive concentration of salt fog. Its core causes are concentrated in the three major links of spray system, salt solution configuration and equipment installation.
First, check the core components of the spray system. Nozzle blockage or wear is the primary cause. The crystal of impurities in the salt solution will adhere to the nozzle aperture, causing deformation or blockage of the spray aperture. When troubleshooting, the device power should be turned off, and the nozzle should be disassembled and soaked in 5% dilute hydrochloric acid for 30 minutes. After removing the crystals, rinse with clean water and dry. If the nozzle is severely worn, it should be replaced with the same type of accessory in a timely manner. Secondly, the unstable pressure of the air compressor will lead to insufficient power for spray. It is necessary to ensure that the output pressure of the compressor is maintained at 0.2-0.4MPa. At the same time, check whether there is air leakage in the air conduit. Coat the interface with soapy water, and reseal the bubbling part.
Improper salt solution configuration will also lead to abnormal spray. The concentration of salt solution should be strictly controlled at 5% (mass fraction). If the concentration is too high, the pipeline will be easily blocked by crystallization. If the concentration is too low, the spray density will be affected. Distilled water or deionized water shall be used during configuration to avoid impurities contained in tap water affecting the spray effect, and at the same time, it shall be stirred evenly to ensure salt dissolution. In addition, the liquid level of the salt tank should be kept between the scale lines. If the liquid level is too low, it will cause the supply pump to run idle and unable to deliver salt normally. It is necessary to replenish the salt in a timely manner and check whether the supply pump is working properly.
The levelness of equipment installation is equally crucial. If the test chamber is not placed horizontally, salt spray will accumulate in low-lying areas due to gravity. A spirit level can be used to detect the four corners of the equipment. By adjusting the bottom anchor bolts, the equipment can be kept level, while ensuring that the sample racks in the test chamber are placed symmetrically to avoid blocking the diffusion path of salt spray.
2、 Temperature inaccurate fault: focusing on the three major modules of "sensing, heating, and temperature control"
Temperature inaccuracy is manifested as a deviation of more than ± 1 ℃ between the actual temperature and the set temperature, or excessive temperature fluctuations, which involve three core modules: temperature sensors, heating systems, and temperature control circuits.
The temperature sensor malfunction is the main cause. Scaling and corrosion of sensor probes can affect temperature sensing sensitivity. It is necessary to regularly disassemble the probe and wipe the surface dirt with a soft cloth. If the probe coating is damaged, it needs to be replaced. At the same time, check whether the sensor wiring is loose or aging, unplug and plug the wiring again, and wrap it with insulating tape to avoid poor contact and signal distortion. In addition, improper sensor installation position will also affect the accuracy of temperature measurement. It should be ensured that the probe is located in the middle of the test box, away from the heating pipe and spray port, and not less than 10cm from the box wall.
The heating system malfunction needs to be thoroughly investigated. Scaling of the heating tube can lead to a decrease in heat dissipation efficiency. The heating tube can be soaked in citric acid solution to remove the scale. If the heating tube melts or bulges, it needs to be replaced with accessories of the same power. At the same time, check whether the heating relay is properly engaged and measure the output voltage of the relay with a multimeter. If the voltage is abnormal, it may be due to the burnout of the relay contacts and needs to be replaced in a timely manner. In addition, poor sealing of the test chamber can lead to temperature loss. It is necessary to check whether the sealing strip of the chamber door is aging or damaged. If the sealing effect decreases, the sealing strip should be replaced and ensure that the chamber door is tightly pressed in place after being closed.
Temperature control circuit faults require professional troubleshooting. Drifting of temperature control instrument parameters can lead to a decrease in temperature control accuracy. The instrument parameters can be recalibrated according to the equipment manual, and the test temperature can be reset after restoring the factory settings. If the instrument display is abnormal, it is necessary to check whether the power supply voltage is stable and eliminate the influence of voltage fluctuations. For complex circuit faults, it is recommended to contact professional maintenance personnel to inspect the main control board, capacitors, resistors, and other components to avoid secondary damage caused by self disassembly.
3、 Daily maintenance: key measures to prevent malfunctions
Regular maintenance is the core of reducing the occurrence rate of failures. It is recommended to clean the salt solution tank and spray system every week, check the temperature sensor and heating pipe every month, and calibrate the temperature display accuracy every quarter. At the same time, standardize the operating procedures to avoid salt overflow and corrosion of equipment. After the test is completed, promptly drain the salt and clean the pipelines to keep the equipment dry and clean. In addition, the equipment should be placed in a ventilated, dry, and non corrosive gas environment, avoiding direct sunlight and severe vibration to extend its service life.
The fault troubleshooting of the salt spray test chamber should follow the principle of "easy before difficult, outside before inside". For the problems of uneven spray and inaccurate temperature, the troubleshooting should be gradual from the core components to the auxiliary system, which can not only quickly locate the fault point, but also avoid equipment damage caused by blind maintenance. Through standardized troubleshooting procedures and daily maintenance, the stable operation of equipment can be effectively ensured, providing reliable support for the accuracy of experimental data.