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Common faults of pressure swing adsorption nitrogen generators and their solutions I. Air pre-treatment system 1. Filters Phenomenon: The pointer of the pressure difference gauge moves into the red zone (the pressure difference is too high). Consequence: It causes an excessive pressure difference, leading to a decrease in adsorption pressure, and ultimately results in a reduction in the oxygen purity flow rate. Solution: Replace the corresponding filter element after shutting down the machine. Note: The lifespan of the filter element for pipeline filters is approximately 6 months; the model for this element is PE1. The lifespan of the precision filter elements is about 12 months, with the model being PE2. The lifespan of the ultra-precision filter elements is around 18 months, and these elements are of the German MF ultrafiltration type. The lifespan of the dust filter element is approximately 18 months, and the element model is PE3. 2. Automatic drain valve (SMC): Phenomenon: Air leaks from the drain port, and the liquid level inside the drain valve exceeds the maximum level (MAX) without any drainage occurring. Consequence: If the automatic drain valve in the air pretreatment section does not discharge waste, it will result in poor water and oil removal efficiency, ultimately affecting the performance of the molecular sieve. Processing: Clean it and put it back in place. Note: A slight amount of air leakage from the drain outlet is normal when in use. 3. Cold dryer: Overview: The cold dryer is a key component of the air preprocessing section; the performance of this device affects the system’s ability to remove oil and water from the air. Normal operating condition: The evaporation pressure is between 0.4 and 0.5 Mpa, usually around 0.41 to 0.42 Mpa ； High-pressure: 1.2~1.6 Mpa for air-cooled types, and 1.4~1.6 Mpa for water-cooled types. Common faults: (1) High high-pressure value: Consequence: If the pressure exceeds 2.0 Mpa, it will trigger the high-pressure shutdown protection of the refrigerated dryer. Air-cooled type: Pay attention to the ambient temperature and the cleanliness of the surface of the air cooler ； Water-cooled type: Check whether the flow rate, temperature, and pressure of the cooling water meet the requirements; turning the water flow control valve clockwise can reduce the high pressure. (2) Low high-pressure pressure: Air-cooled type: Check and adjust the settings of the fan’s high and low pressure switches. Water-cooled type: Adjust the water flow control valve counterclockwise. (3) High evaporation pressure: Consequence: It affects the water removal efficiency of the cold dryer, as well as the oil removal efficiency in subsequent stages. Solution: Adjust the hot gas bypass valve counterclockwise or adjust the expansion valve counterclockwise. (4) Low evaporation pressure: Consequence – ice blockage may occur (water vapor in compressed air condenses directly into ice, causing blockages in the pipes). Note: The valves for the hot gas lines, the water flow control valves, and the high/low pressure switches, as well as the expansion valve, are not independent of each other; adjustments to these valves need to be made while monitoring the instruments, until the parameters show within the normal range. (See the desiccant dryer user manual for details.) 4. Activated carbon oil remover: As the final barrier to protect the molecular sieve, the importance of this oil remover is self-evident. Note: The service life of the activated carbon in the oil remover is approximately one year. To protect the lifespan of the molecular sieve, the activated carbon must be replaced annually; it also needs to be replaced after an oil leakage issue occurs in the air compressor. (to be continued)