Xylem LN - Manual (Page 49)

Installation, Operating and Maintenance Instruction Model L, LN
Page 45
2.7.2 Permitted Nozzle Loads and Torques
Basically the suction and discharge piping must
be designed in such way, that as little forces as
possible are effective to the pump. If that is not
possible, the values shown in chapter 3.5 must
not be exceeded under any circumstances. This
is valid for the operation as well as for the
standstill of the pump and therefore for all
possible pressures and temperatures of the
unit.
2.7.3 NPSH
The pumped liquid must have a min. pressure
NPSH at the impeller inlet; so that cavitations
free work is secured resp. a "break off" of the
pump flow is prevented. This condition is
fulfilled, when NPSH-value of the system
(NPSHA) lies above NPSH-value of the pump
(NPSHR) under all operating conditions.
Attention must especially be paid to the NPSH-value
on pumping liquids near the vapour pressure. If the
NPSH-value of the pump remains under, this can lead
from damage of the material due to cavitations to
destruction by overheating.
The NPSH-value of the pump (NPSHR) is shown in
the curves of every pump type.
2.7.4 Back Flow
In systems where pumps are operating in closed
circuits under pressure (gas cushions, steam
pressure), the pressure of the gas cushion must not
be reduced via the pump, since the back flow speed
may be much higher than the operating speed, which
would destroy the unit.
3. Description
3.1 Design
The pumps of Model L and LN are single-stage volute
casing pumps acc. DIN EN 733.
These pumps are not qualified for dangerous or
inflammable fluids. Not qualified for the
operation in areas subject to explosion hazards.
Maximum working pressure: see chapter 3.2
"Maximum permitted working pressure and
temperature".
The permitted application conditions and design
details of the delivered pump are shown in the
attached data sheet and / or the order confirmation.
The appropriate sectional drawing of the supplied
pump as well as the pump weight and the complete
pump unit weight are shown in the appendix.
3.2 Maximum permitted working pressure
and temperature
0
2
4
6
8
10
12
14
-20 0 20 40 60 80 100 120 140 160
Temperatur - Température - Temperature t
max op
[°C]
D
ruc
k - P
re
ssion - P
re
ssure
p
a ll w
C
[
ba
r]
Flansche/Bridges/Flanges PN 16, 0.6025
Flansche/Bridges/Flanges PN 10, 0.6025
0
2
4
6
8
10
12
14
16
18
-20 0 20 40 60 80 100 120 140 160
Temperatur - Température - Temperature t
max op
[°C]
D
ru
ck
-
P
re
ssi
o
n
-
P
re
ssu
re
p
a ll w
C
[
ba
r]
Flansche/Bridges/Flanges PN 10/16, 0.6020
L
LN