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Dealing with the problem that reverse osmosis pure water equipment cannot start normally

Sep 04, 2020

First of all, the reverse osmosis pure water equipment cannot be turned on during the inspection process. The process of sequential inspection is to check whether the power plug is plugged in and whether the power supply is powered. Check whether the power switch cable is disconnected and reconnect the power cable. The system displays that there is no water and sounds an alarm to indicate that the inlet water pressure is lower than the set value. Please check whether the water source is open, whether there is water in the system, or whether the water pressure of the tap water is lower than 0.1MPa. If so, please improve the water inflow to the proper water pressure. If the water intake is normal, check whether the pretreatment filter element is clogged. If it is clogged, clean or replace the pretreatment filter element.

After field testing, it was found that the reverse osmosis pure water equipment could not be started because the pressure protection switch on the water inlet pipe and the water passage of the pressure protection switch in front of the high-pressure pump were blocked by rust, unable to sense pressure, and unable to output signals to PLC control Program, the device cannot be started. After testing, the turbidity of the effluent of the sand filter tank is not higher than 1.0NTU, which meets the requirements of entering the security filter, and the security filter is not likely to be blocked by solid impurities.

Cut slices of the same size from the clogged security filter and put them into the dilute hydrochloric acid solution. After 5 minutes, you can see that the security filter core slices in the hydrochloric acid solution have recovered white. The pressure protection switch was disassembled, and it was found that the water inlet pipe of the pressure protection switch had been blocked by yellowish brown material. After cleaning the pipeline, the pressure protection switch can reflect the water pressure normally. Water quality analysis showed that the iron ion content in the water body was as high as 0.5ppm at this time, and large yellow-brown patches were visible to the naked eye in the removed reverse osmosis membrane, and there were yellow-brown material accumulation at both ends of the membrane.

Through the inspection of the water inlet pipeline of the reverse osmosis equipment, it was found that the reason for the increase of iron ions was the use of the booster pump. The booster pump is introduced to ensure that the equipment has sufficient pressure to meet the pressure requirements of the sand filter and to ensure that the high-pressure pump has sufficient starting pressure. However, the salt content of the raw water is as high as 1.5g/L. Inappropriate selection of the booster pump causes the booster pump to corrode rapidly, causing a large amount of iron ions to enter the pipeline. However, the equipment was designed based on raw water, and there was no device for treating iron ions, which caused the sudden introduction of iron ions to affect the safe operation of the equipment. After stopping the use of the booster pump and cleaning the water pipe of the pressure protection switch, the equipment resumes normal operation.

Through failure analysis, the reason that the reverse osmosis pure water equipment cannot start normally and the security filter is blocked is the increase of iron ions in the raw water. These iron ions are reduced ferrous ions in raw water and can be dissolved in water. The water is adsorbed by the security filter or accumulated in the pipeline of the pressure switch. After the equipment is shut down, it is oxidized by the oxygen in the air and becomes insoluble trivalent iron, which is insoluble in water, resulting in the security filter element and pipeline. The blockage affects the normal operation of reverse osmosis pure water equipment.

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