ISO 9906: How to Select Efficient Pumps

The specifications given herein refer to the curves given in our catalogues and Data Books (see www.ebaraeurope.com).
All performance curves have been calculated in compliance with ISO 9906 Annex A.
Tolerances per ISO 9906 Annex A.
The curves refer to the effective speed of the asynchronous motors at 50 Hz.
The measurements were run at a water temperature of 20°C with dynamic viscosity of ν= 1 mm/s (1 cSt).
The NPSH curve is a mean curve obtained in the same conditions as the performance curves.
The continuous curves represent the recommended working range. The broken curve is only a guide.
To prevent overheating, the pumps should not be used below 10% of the maximum efficiency flow rate.
When selecting the pump, make allowance for a safety margin of at least 1 m.
Symbols: Q = Flow rate [m/h]
H = Head [m]
P1= Power draw from power line
P2= Power delivery to motor shaft (pump power draw)
η = Pump efficiency
NPSH = Net positive suction head required by the pump
MEI = Minimum Efficiency Index
The minimum efficiency index (MEI) measures the quality of a pump in relation to its efficiency.
The minimum efficiency index is based on hydraulic performance and refers to the maximum efficiency point.
The efficiency of a pump with turned impeller is generally lower than that of a pump with full impeller diameter.
Turning of the impeller adapts the pump to a fixed work point, resulting in lower energy consumption.
The minimum efficiency index (MEI) is based on the maximum diameter of the impeller.
The operation of the pump for water with variable operating points can be efficient and cost-convenient if it is controlled, for example, through a variable-speed motor that adjusts the pump’s operation to the system.