Confusions regarding reverse osmosis pressure issues
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Everyone, after performing online cleaning on our 25 tons/hour reverse osmosis system, the water production rate, as well as the pressure behind the pump, the pressure between stages, and the pressure of the concentrated water have remained stable over the past three months. However, recently there have been sudden changes: the pressure behind the pump dropped from 1.4 MPa to 1.24 MPa, the pressure between stages decreased from 1.28 MPa to 1.1 MPa, and the pressure of the concentrated water also decreased slightly, though not by much. Meanwhile, the water production rate fell from 292 L/min to 262 L/min. The decrease in water production rate can be explained, but what is the reason for the overall drop in pressure? Please help analyze this.
The filter element of the security filter may be clogged.
I’m not sure if the pressure mentioned by the poster refers to the pressure shown on the gauge at the pump outlet. If the pressure gauge is fine. The following analysis can be done: Determine whether your pump is variable-frequency or a centrifugal pump with a fixed speed. So, the characteristic curve of a pump. The flow rate at 1.4 MPa is lower than that at 1.24 MPa. In other words, the traffic to your system has increased. Based on the solution method for pump operating conditions. The operating conditions of the pump are determined based on the pump’s performance curve and the system’s pressure drop curve. You can reduce the valve opening, thereby increasing the system’s pressure drop and altering the operating point of the pump; this results in an increase in the pump’s head and a decrease in its flow rate.
There is nothing wrong with my pressure gauge. If what’s said on the 3rd floor is true, then the system flow rate has increased, but in reality the total water inflow has decreased, as the amount of concentrated water discharged remains unchanged and the water production volume has dropped.
Check the filter element to see if it needs to be replaced, and check if there are any changes in the concentrated water control valve
It is possible to check whether the raw water pump and high-pressure pump are operating properly, as well as whether the control valves are opening correctly If everything is fine, it’s time to replace the filter element.
It is likely caused by an increased pre-treatment pressure difference. First, check the filter element, and then see if the operating pressure difference of the multi-media or ultrafiltration system itself has increased.
Hehe, if the original poster manages to solve it, please share it with us. We haven’t dealt with this issue before; we hope an expert can resolve it
There are two reasons: 1 is that the filter element is clogged; 2 is that the pump’s flow rate is low. Check whether there is dirt on the pump’s impeller. This post was last edited by lhzjl on 2009-4-17 at 17:22.]
There could be two reasons for this phenomenon: 1. The pump may be worn out or faulty; a test using clean water can be conducted to check whether it still delivers the required output； 2. An increase in resistance in the inlet pipes leads to a reduction in flow rate, which in turn affects the pump’s pressure. It is necessary to check whether all valves are open, as well as to examine the system ahead of the pump for any factors that might cause an increase in pipe resistance, such as whether the filtration system is functioning properly and there are any leaks
If the pressure gauge is fine, then there are only two possibilities. First, check the pressure before the pump; if it’s no different from before, it means there’s a problem with the pump. Second, if the pressure before the pump is lower than before, it indicates that the pre-treatment system (mechanical filter, safety filter) is clogged – in that case, replace the filter elements and clean the filters promptly
Since your flow rate has also decreased, it’s probably not a problem with the high-pressure pump. The pump you’re referring to is probably the high-pressure pump located after the security filter. If so, then check the pressure difference before and after the strainer. If the pressure after filtration by the security system increases, it’s time to replace the filter element. Also, check whether the strainer is leaking air. You can contact the equipment supplier.
Based on the phenomena you described, it seems that there is a problem with the high-pressure pump before the reverse osmosis process. It’s very likely that there is an issue with the impeller section, which results in less water being discharged and a corresponding decrease in pressure. As the water inflow decreases, the water output will surely drop, and the concentration of the liquid also decreases.
The water pressure at the outlet of the high-pressure pump has decreased, and the flow rate has also dropped; one possible reason is that the pressure of the water source has fallen. The second issue is that the pressure difference across the sand filter, carbon filter, fine filter, and safety filter is too high; the sand filter and carbon filter are cleaned in turn, one after the other, which is likely to result in a high pressure difference across the fine filter and safety filter. The third scenario is a decrease in the performance of the high-pressure pump, resulting in a drop in both head and flow rate; for example, if the inlet pressure remains unchanged, the outlet pressure may drop by 20%. It’s easy to make a judgment once those production figures are clarified.
1. Check whether the pressure difference across the strainer filter has increased. 2. Check whether the concentrated water discharge valve is open too wide. 3. Check whether the pressure of the ultrafiltration pump before the high-pressure pump has decreased. 4. If nothing is wrong with the above, there may be a problem with the high-pressure pump
1. If the pressure drops, check whether there is a change in water temperature during operation before and after; it is normal for the pressure to decrease when the water temperature rises； 2. The water production rate has decreased from 292 L/min to 262 L/min; this may be due to A、the deformation or clogging of the pre-filtration elements in the reverse osmosis system, or B、the need for minor maintenance in the system, as microorganisms reproduce more rapidly in spring ； 3. For the equipment, find an engineer to check if there are any issues ；
1. The filter element of the precision filter is dirty. 2. The outlet pressure after pretreatment is low. 3. There is a problem with the high-pressure pump. The first two options are more likely. If the first two items are ruled out, it’s a problem with the high-pressure pump. We have encountered it before
It’s likely that the filter element of the security filter needs to be replaced.