Failure Analysis of Reverse Osmosis Water Purifier Unable to Start

The placement requirements of the reverse osmosis water purifier are relatively high, so the environmental requirements are relatively high. First of all, select hundreds of common desktop reverse osmosis water purifiers, which can be placed on a flat workbench. There should be enough space near the entire system to connect water pipes, power supplies and replace consumables. Please install the machine near the water source, power supply and water tank. The requirement for water source environment is that the system takes tap water as the water source, and the required inlet pressure is 1.5-3.5Kg/CM3. The inlet pipe diameter shall not be less than 4 branch pipes. The hardness of the influent should be considered. If the hardness is high, the influent should be softened first.

The reverse osmosis pure water machine should be operated in a standardized manner. Whether in the selection of environment or in the case of failure, it should be operated according to the corresponding process, so that there will be no unnecessary loss. For systems with purified water as the water source of reverse osmosis water purifier equipment, the TDS value of influent water shall be less than 20PPM. The power supply required for the reverse osmosis water purifier is all systems with a water yield of 15L-125L/h. The required power supply is 220V/10A three-hole and two-hole national standard socket. These are the necessary requirements for the environment of the reverse osmosis water purifier before installation.

When the reverse osmosis water purifier fails to check, press the pure water key or the ultra-pure water key to take out the water, indicating that the water level in the water storage tank has been lower than the low level switch. At this time, please wait patiently for the equipment to make water. When the water level in the tank exceeds the low level switch, you can take water. It indicates that the liquid level switch of the water storage tank may not have good contact with the liquid level signal line of the ultrapure water machine. Please check and improve.

The reverse osmosis water purifier has some small faults in daily life, which should be checked reasonably. First, the reverse osmosis water purifier cannot be started during the inspection process. The process of checking in order is to check whether the power plug is plugged in properly and whether the power supply is powered on. Check whether the connecting wire of the power switch falls off and reconnect the power cable. The system displays no water and sends 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 is lower than 0.1MPa. If yes, please improve the water inlet to the proper water pressure. If the water inflow is normal, check whether the pretreatment filter element is blocked. If it is blocked, clean or replace the pretreatment filter element.

Analysis and solution of reverse osmosis equipment failure to start

Through field test, it was found that the reverse osmosis equipment could not be started because the water passage of the pressure protection switch on the water inlet pipeline and the pressure protection switch in front of the high-pressure pump was blocked by rust, and the pressure could not be sensed, so the signal could not be output to the PLC control program, resulting in the equipment could not be started. According to the test, the turbidity of the outlet water from the sand filter tank is not higher than 1.0NTU, which meets the requirements for entering the security filter. The security filter is not likely to be blocked by solid impurities.

Cut slices of the same size from the blocked cartridge filter and put them into dilute hydrochloric acid solution. After 5 minutes, you can see that the cartridge slices in the hydrochloric acid solution return to white. As shown in Figure 3. After removing the pressure protection switch, it was found that the water inlet pipe of the pressure protection switch had been blocked by yellow-brown substances. After cleaning the pipeline, the pressure protection switch can normally reflect the water pressure. The water quality analysis shows that the iron ion content in the water body is as high as 0.5ppm at this time, while the naked eye can see large yellow-brown patches in the removed reverse osmosis membrane, and there are yellow-brown substances 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 booster pump. The booster pump is introduced to ensure that the water inlet of the equipment has sufficient pressure to meet the pressure requirements of sand filtration and ensure that the high-pressure pump has sufficient starting pressure. However, the salt content of raw water is as high as 1.5g/L, and the improper selection of booster pump causes the booster pump to corrode rapidly, causing a large amount of iron ions to enter the pipeline. However, the equipment is designed according to the raw water, and there is no device to treat iron ions, resulting in the sudden introduction of iron ions affecting the safe operation of the equipment. After the booster pump is stopped and the overflow pipeline of the pressure protection switch is cleaned, the equipment returns to normal operation.

Through fault phenomenon analysis, the reason why the equipment can not 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 stored in the pipeline of the pressure switch. After the equipment is shut down, it is oxidized by oxygen in the air and becomes insoluble trivalent iron, which is difficult to dissolve in water, causing the blockage of the security filter element and pipeline, and affecting the normal operation of the equipment.

Cause of reverse osmosis equipment failure:

Through the on-site commissioning, operation and investigation of reverse osmosis equipment, it is found that most of the faults occurred in the operation of reverse osmosis equipment are due to improper protection and use. In terms of reverse osmosis equipment design, theoretically selectable protection measures include pretreatment dosing protection, optimization of pretreatment process, and improvement of monitoring instruments. However, for rural users, there are problems such as lack of professional and technical background of users and equipment costs. Generally, the reverse osmosis equipment used in rural areas is maintained and operated by the village. Most of the equipment users lack professional background and can not complete the maintenance and management of the equipment well. In this case, the equipment with high degree of automation and simple operation and maintenance will be more convenient for farmers to use.

In order to ensure the stable operation of reverse osmosis equipment, complete design is the first priority. This requires the designer to fully consider the complexity of rural brackish water treatment and the details of water production, including water quality, water production scale, equipment operation status, use location, user's professional background, etc., in the process of designing products and projects, rather than simply completing the connection of various components. Technically, over-automatic equipment is not suitable for the current rural market, while online cleaning device is necessary. At the same time, modular design can be considered to facilitate the replacement and maintenance of equipment. The raw water quality and the possible water quality changes during equipment operation should be fully understood, and protective measures should be taken.

With the increase of equipment automation, the investment in equipment will also increase; The automatic equipment has the characteristics of too many monitoring and control elements, too sensitive equipment and high failure rate. These failures are often not caused by the equipment itself, but by the failure of the monitoring equipment, such as the blockage of the pressure protection switch mentioned above. As a result, rural users spend a high price to buy highly automated equipment, but can not guarantee the continuous operation of the equipment.