why pipe diameter increases after pump discharge
why pipe diameter increases after pump discharge
(OP)
i have noticed on most,if not all, situations that there is a reducer pipe installed immediately after centrifugal pump discharge to increase the diameter of the discharge pipe. why?





RE: why pipe diameter increases after pump discharge
However economic sizing of the downstream pipe usually requires a larger pipe.
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RE: why pipe diameter increases after pump discharge
The discharge nozzle size of a pump is sized to relate to the velocity of the flow for which the pump is designed.
The suction nozzle size is usually sized one size larger than the discharge nozzle. Some exceptions are noted in the case of solids-handling pumps where the suction nozzle size is made the same size as the discharge nozzle so that particles that enter the pump can also exit the pump. This assumes that the impeller design in that pump will also pass the same particle size.
The reducer on the inlet side of a pump ensures that the velocity of liquid in the suction line is slowed sufficiently to provide a smooth flow of liquid with minimized friction losses in the pipeline to ensure as high as possible an NPSH available from the system.
The pipe increaser (reducer) on the discharge side of the pump increases the diameter of the discharge pipeline at the pump nozzle to reduce the velocity of the liquid in the discharge pipeline. The lower velocity reduces the friction head which allows the pumping system to operate at a lower pressure.
The pump nozzle size is related to the design of the pump. The discharge pipeline size is related to the friction head of the pumped fluid.
RE: why pipe diameter increases after pump discharge
For the suction side, the practical reason is that the maximum velocity in the pipeline should be limted to around 5 ft/s. Anything higher will result in excessive friction loss which could affect the NPSHa
We as designers don't care why the pump manufacturer size their pump nozzles the way they do. They have their own reasons. We just care about the piping connecting to the pump nozzle.
RE: why pipe diameter increases after pump discharge
RE: why pipe diameter increases after pump discharge
For example we can't put an elbow less than something like 5 pipe diameters from the pump.
Is it ok to put a reducer right next to the pump?
(I see them that way all the time, just double checking whether it makes sense)
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(2B)+(2B)' ?
RE: why pipe diameter increases after pump discharge
If you have a vertical flange then a concentric reducer should be fine if connected directly to the flange, IMHO.
Remember - More details = better answers
Also: If you get a response it's polite to respond to it.
RE: why pipe diameter increases after pump discharge
Depends somewhat on the type of pump and application.
Split case pumps require a long radius elbow on the inlet. Different straight run recommendations would be made for lower and higher fluid velocities.
https://blog.craneengineering.net/5-basic-rules-of...