Best efficiency point (BEP)
The best efficiency point (BEP) is the flow rate where a pump has its highest
efficiency, and is normally based on its performance at maximum impeller
diameter. The best efficiency point (BEP) is an important parameter because:
The flow at BEP is not necessarily the same as the design flow of its impeller. The
BEP is controlled by both the impeller and the volute. A particular impeller will yield
different performances with varying BEP if it is installed in different sizes of volutes.
A volute with a smaller throat area will pull the BEP to a lower flow rate, and will
lower the pump NS. A volute with larger throat area will pull the BEP to a higher
flow rate, and will increase the pump NS. An impeller which is matched to the
correct volute throat area will yield the optimum pump performance.
Questions:
Is it a good practice to base the minimum stable flow, the preferred operating flow
range, and the allowable operating flow range on a percentage of BEP? Is there
an alternate method to this practice?
An article discussing these issues is available by request. [ * ]
[ * ] Some information are excluded. Read more.
R: 0110-BEEF
C: design, operation
F: BEP
Beta version
The best efficiency point (BEP) is the flow rate where a pump has its highest
efficiency, and is normally based on its performance at maximum impeller
diameter. The best efficiency point (BEP) is an important parameter because:
- Other parameters such as specific speed (NS), suction specific speed
(NSS), hydrodynamic size (Z), viscosity correction, etc., are calculated from
pump data taken at its BEP.
- It is common practice to base a pump's recommended minimum stable
flow, its preferred operating flow range, and its allowable operating flow
range, as a percentage of its BEP.
- Many users prefer their pumps to operate within 80% to 110% of their BEP
for optimum performance, to minimize their hydraulic radial and thrust
loads, and to avoid vibration problem induced by low flow recirculation.
The flow at BEP is not necessarily the same as the design flow of its impeller. The
BEP is controlled by both the impeller and the volute. A particular impeller will yield
different performances with varying BEP if it is installed in different sizes of volutes.
A volute with a smaller throat area will pull the BEP to a lower flow rate, and will
lower the pump NS. A volute with larger throat area will pull the BEP to a higher
flow rate, and will increase the pump NS. An impeller which is matched to the
correct volute throat area will yield the optimum pump performance.
Questions:
Is it a good practice to base the minimum stable flow, the preferred operating flow
range, and the allowable operating flow range on a percentage of BEP? Is there
an alternate method to this practice?
An article discussing these issues is available by request. [ * ]
[ * ] Some information are excluded. Read more.
R: 0110-BEEF
C: design, operation
F: BEP
Beta version
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