Johnson Pump SPX Flow CombiBlocHorti Series, Instruction Manual

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18 General
CL-CBH/EN (1901) 7.6
2.6.3 Energy Efficient Pump Selection
In selecting the pump, care should be taken to ensure that the duty point required is as
close as possible to the pump’s Best Efficiency Point (BEP). Different heads and flows
can be achieved by changing the diameter of the impeller and thereby eliminating
unnecessary energy loss.
The same pump can be offered at different motor speeds to allow the pump to be used
over a much wider range of duties. For instance, changing from 4-pole motor to 2-pole
motor will enable the same pump to deliver twice as much peak flow at 4 times the head.
Variable speed drives allow the pump to operate efficiently over a wide range of speeds
hence duties in an energy efficient manner. They are particularly useful in systems where
is a variation in required flow.
A very useful tool for energy efficient pump selection is the downloadable software
program “Hydraulic Investigator 2” from the SPXFLOW website.
Hydraulic Investigator is the selection guide for centrifugal pumps and search by pump
family and pump type starting from entering required capacity and head. Further refine
the pump curves to find the pump that meets your specification.
The default setting of applicable pump types is prioritized on highest efficiency. In the
standard automated selection procedure the optimum (trimmed) impeller diameter is
calculated already, where applicable. Manually the rotating speed can be adjusted as
well when a variable speed drive is preferred.
Example:
Curve 1: performance at maximum impeller diameter and 2960 rpm;
Curve 2: performance at required duty point (180 m
3
/h, 30 m) with trimmed impeller,
power consumption 18,42 kW;
Curve 4: performance at required duty point with maximum diameter and reduced
rotating speed (2812 rpm), power consumption 18,21 kW.
Figure 2: Hydraulic Investigator 2