KSB MK, Installation & Operating Manual

Page: 30 / 64

6 Commissioning/Start-up/Shutdown
30 of 64
MK
6.2.3 Fluid handled
6.2.3.1 Flow rate
Unless specified otherwise in the characteristic curves or in the data sheets, the
following applies:
▪ Short-time operation: Q
min
4)
= 0.1 × Q
opt
5)
▪ Continuous operation: Q
min
4)
= 0.3 × Q
opt
5)
▪
2-pole operation: Q
max
6)
= 1.1 × Q
opt
5)
▪ 4-pole operation: Q
max
6)
= 1.25 × Q
opt
5)
The data refer to water and water-like fluids. Longer operating periods with these
fluids and at the flow rates indicated will not cause an additional increase in the
temperatures on the pump surface. However, if the physical properties of the fluids
handled differ from those of water, the calculation formula below must be used to
check if an additional heat build-up may lead to a dangerous temperature increase at
the pump surface. If necessary, the minimum flow must be increased.
×
×
×
Table 8: Key
Symbol Description Unit
c Specific heat capacity J/kg K
g Gravitational constant m/s²
H Pump discharge head m
T
f
Fluid temperature °C
T
O
Temperature at the casing surface °C
Pump efficiency at duty point -
Temperature difference K
6.2.3.2 Minimum level of fluid handled
DANGER
Pump set running dry
Explosion hazard!
▷ Never allow an explosion-proof pump set to run dry!
CAUTION
Fluid level below the specified minimum
Damage to the pump set by cavitation!
▷
Never allow the fluid level to drop below the specified minimum.
Minimum 120 mm above the bottom edge of the casing; if handling condensate ~400 mm
Maximum 150 mm below the plate
Before start-up, the pump set must always be immersed in the fluid to be handled so
it is above the minimum switch-off level (
ð
Section 6.1.2, Page 27) .
4) Minimum permissible flow rate
5) Flow rate at best efficiency point
6) Maximum permissible flow rate