The combination of two valves at the pump outlet in the one standby one in use mode is open for active discussion by everyone.
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https://bbs.hcbbs.com/forum.php?mod=image&aid=1383613&size=300x300&key=03ceb**6106740&nocache=yes&type=fixnone In the process piping, there are two possible configurations for the outlet valves of the pumps; the fluid contains some sediment. The process is as shown in the diagram above. 1. A check valve is installed at the outlet of each pump, followed by a ball valve, and then the outlet pipelines are combined together. The pressure gauge is connected before the check valve； 2. Ball valves are installed at the outlets of both pumps; the pipelines are combined together and then a check valve is connected, with the pressure gauge placed before the ball valve. Everyone is welcome to leave comments actively and discuss the advantages and disadvantages of these two methods.
The difference between the first and second options shown in the diagram is that they do not share an outlet check valve. This appears to require more investment, but if there is internal leakage in the outlet valve in option one, it becomes problematic; moreover, maintaining the backup pump becomes difficult. In option two, the check valve is installed at a higher position, making maintenance inconvenient. It is recommended to use the configuration shown in option one.
In Figure 2, we plan to install the check valve at a height of about 1 meter above the ground. I didn’t draw the inlet ball valves for these two diagrams.
The standard specifies preparation according to Figure 1. As for Figure 2, there are several drawbacks: 1. The installation location of the check valve in Figure 2 is not conducive to liquid drainage; normally, a drain valve is placed after the check valve. 2. The position in Figure 2 is too high, far away from the pump, which hinders equipment protection. 3. Normally, safety valves should be installed vertically for better reseating, whereas in Figure 2 the pipelines are generally in a horizontal position. 4. When the check valve in Figure 2 fails, it cannot be repaired – although this might seem good, it is actually very impractical
Thank you for your feedback； I feel that troubleshooting the check valves in Figure 1 and Figure 2 is quite troublesome ； In Figure 2, the collection pipe here is vertical; I wanted to save some space, but it always seems a bit odd.
Generally, the first option is used; I don’t think the second one has been used before. Since both pumps are being sold, there’s no need to save money on this check valve. Besides, it’s inconvenient to carry out maintenance, even if the location isn’t high.
Figure 2 is incorrect; in the event of internal leakage in the valve of the backup pump, it could cause the impeller to rotate in the reverse direction.
Our companies all use piping according to Figure 1, which is more reasonable.
The first option is the conventional setup method, while the second one can help save some costs; however, its downside is that it cannot prevent damage caused by the pumps running in reverse due to human error during the switching process between the two pumps
Generally, the first option is preferred, but it is recommended to include a control valve in between; this way, repairing an individual outlet valve does not affect the operation of the pump. The second option is not advisable, as it involves the lack of a valve, and from the perspective of total cost and subsequent maintenance, it is not worthwhile.
A check valve should be installed in front of the outlet valve to prevent backflow of the fluid inside the pump, which would complicate maintenance; drain pipes should be installed behind the check valve and in front of the inlet valve