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14
Hydraulic control,
nhi
m
p
Hsi
Qi
Phyi
81
.
9
, where
5
.
0
75
.
0
1
98
.
0
Hn
Hst
Qi
Qi
nhi
The rated efficiency of hydraulic coupling is assumed to be 98%.
The required power for the compared control method is calculated and the
energy consumption per year is thereafter calculated from the formula
Pi
Tki
E
Unit Conversions
The formulas above use metric measurement units. In the case US units have
been selected to be used in entering the data and presenting the results, the
following conversion factors have been used:
Nominal volume flow
Q
n:
[gpm]* 0.22712471=[m³/h]
Head
H:
[ft]* 0.3048 =[m]
Liquid Density
D:
[lb/ft³]* 0.016018463=[kg/dm³]
Nominal Power
P:
[Hp]* 0.7457=[kW]
Mass (weight)
m:
[lb]*0.4536=[kg]