PERFORMANCE CURVE SPECIFICATIONS
The specifications below qualify the curves shown on the following pages.
Tolerances according to ISO 9906:2012 – Grade 3B
The curves refer to effective speed of asynchronous motors at 50 Hz, 2 poles.
Measurements were carried out with clean water at 20°C of temperature and with a kinematic viscosity
of = 1 mm
2
/s (1 cSt)
The continuous curves indicate the recommended working range. The dotted curve is only a guide.
In order to avoid the risk of over-heating, the pumps should not be used at a flow rate below 10% of best
efficiency point.
Rev. P
Symbols explanation:
Q
=
H
=
P
2
=
=
MEI =
volume flow rate
total head
pump power input (shaft power)
pump efficiency
minimum efficiency index
The minimum efficiency index (MEI) is a measure of the quality of a pump size in respect to its mean
efficiency. The minimum efficiency index is based on the hydraulic efficiency and on the head at the best
efficiency point.
The benchmark for most efficient water pumps is MEI ≥ 0,70.
Information on benchmark efficiency is available at: www.ebaraeurope.com
The efficiency of a pump with trimmed impeller is usually lower than that of a pump with the full impeller
diameter. The trimming of the impeller will adapt the pump to a fixed duty point, leading to a reduced
energy consumption. The minimum efficiency index (MEI) is based on the full impeller diameter.
The operation of these water pumps with variable duty points may be more efficient end economical when
controlled, for example, by the use of a variable speed drive that matches the pump duty to the system.
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