salmson NEX, Installation And Operating Instructions Manual

Page: 37 / 92

ENGLISH
9
Open impeller generated rear pressure :
Pressure
In MS housing
[bar]
Differential
pressure
[bar]
Reverse vane impellers generated rear pressure :
Pressure
In MS housing
[bar]
Differential
pressure
[bar]
Hydrostatic test pressure : 1,5 x PS
5.2.2.3 MINIMUM FLOW FOR CON TINUOUS
OPERATION
Permitted flow range :
Q
opt
is the constant flow corresponding to Best Efficiency Point.
Pump should work between 80% and 110% of Q
opt
.
PUMP SIZE
Q
mini
5% Q
opt
Impeller

125
Q
mini
5% Q
opt
Impeller

160
Q
mini
26% Q
opt
125-100-160
Q
mini
5% Q
opt
Impeller

200
Q
mini
13% Q
opt
100-65-200
Q
mini
28% Q
opt
125-100-200
Q
mini
5% Q
opt
Impeller

250
Q
mini
13% Q
opt
125-100-250
Q
mini
28% Q
opt
150-125-250
Q
mini
35% Q
opt
200-150-250
Q
mini
5% Q
opt
Impeller

315
Q
mini
9% Q
opt
125-80-315
Q
mini
13% Q
opt
150-125-315
Q
mini
28% Q
opt
200-150-315
Q
mini
5% Q
opt
Impeller

400
Q
mini
13% Q
opt
200-150-400
When the pump is used in an ATEX zone it is necessary to
measure the duty point and check that temperature
increase corresponding to each working condition is acceptable
regarding selected surface temperature.
The formula below gives the correspondence between surface
temperature / fluid temperature and pump efficiency :
T
o
=T
f
+

v

v
=[(g.H)/(c.

)]*(1-

)
With :
c=calorific capacity of fluid in J/Kg.K
g=gravity in m/s²
H=pump head in m
T
f
=liquid temperature in °C
T
o
=surface temperature in °C

=hydraulic efficiency at duty point

v
=differential temperature
5.2.2.4 MAXIMUM ALLOWABLE SP EED AND
NUMBER OF STARTS PER HOUR
Maximum speed :
The maximum speed for each bearing bracket size is indicated in
the table below. The critical speeds of the impellers are much
higher than the maximum allowable speed of the corresponding
bearing bracket.
BEARING BRACKET
SIZE
SPEED
RPM
24 4700
32 3600
42 3600
48 2000
Number of starts per hour :
Wait for pump full stop before starting-up the pump again
to avoid damaging the motor and the pump.
Starting frequency depends on motor type. Ask
manufacturer if necessary.
It is recommended to limit the number of starts per hour to :

15 starts per hour up to 15KW,

10 starts per hour up to 90KW,

6 starts per hour for higher installed powers.
5.2.2.5 TYPE OF HANDLED FLUIDS
The pump is used to transfer clear liquids or slightly laden fluids.
Fluid maximum viscosity is 500 cSt (mm² ).
It is possible to pump fluids containing particles when pump is run
at 1450 RPM with the following restrictions :

Solids size smaller than 1 mm : 10% maxi in volume.

Light particles with smaller size than 1 mm : 35% maxi of the
volume but liquid specific gravity should not be modified.
Pump can occasionally handle bigger size of solids but it will
drive to a reduction of pump life, increasing of equipment
noise level and absorbed power.
Free passage depends on the pump size :
PUMP SIZE
MAX
size
(mm)
32-20-200 Ø5
32-20-160 40-25-250 Ø6
40-25-125 100-80-125 40-25-160 Ø7
50-32-125 50-32-160 40-25-200 Ø8
65-40-125 50-32-200 50-32-250 Ø9
80-50-125 65-40-250 50-32-315 Ø10
65-40-200 Ø10.5
65-40-160 80-50-160 125-100-160 Ø11