Pump performance issues
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I just saw a post saying that check valves aren’t necessary at the outlet of those pumps. Someone replied that if the pump itself doesn’t have any restrictions against reverse operation, then such valves aren’t needed. Are there really pumps that don’t have any restrictions against reverse operation? Thank you
The reversal is mainly to prevent the impeller nut from loosening. Only for vane pumps
All pumps must not be operated in reverse, otherwise their performance will **decrease**.
A check valve is generally installed at the outlet of a centrifugal pump to prevent backflow of liquid and reverse rotation of the impeller. This is especially important in systems with continuous automatic control. However, in many cases where manual operation is used, a check valve may not be installed; when starting the pump, one should first close the outlet valve, which helps to avoid the aforementioned issues of backflow and impeller reversal. On the other hand, even if a check valve is installed, if it fails at some point, it alone won’t be sufficient. It’s important to develop good operating habits and pay attention to the maintenance of the pump to ensure it operates as efficiently as possible
It’s still best to install them, especially on more expensive pumps. Even if you normally stop the pump manually, a power outage can cause it to stop suddenly, which can cause significant damage to the pump. Our pumps basically all come equipped with check valves at their outlets
Previously, check valves were installed after the pump outlet valve, with the operating pump and the standby pump sharing one. Currently, check valves are installed in front of the pump outlet valve, one for each pump. The purpose of this is to prevent the material from flowing back into the pump body when the pump stops operating, thereby avoiding high pressure from reaching low pressure areas. The design used abroad also involves placing these valves in front of the pump; the advantage of this is that it allows for testing whether the check valves are functioning properly, as well as enabling maintenance to ensure their proper operation. The downside is that the position of the pump outlet valve becomes higher, which leads to the need for a reducing check valve; this helps to eliminate the need for tees and short pipes, thereby reducing the height of the pump outlet valve! I’ve never seen a pump that doesn’t have a check valve.