Lowara LEZ 125-200 UNL 3702 [8/19] Model ler lers lez
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Lowara LEZ 125-200 UNL 3702 [8/19] Model ler lers lez

Lowara LERS 150-200 UNL 4502 [8/19] Model ler lers lez
Installation, Operation and Maintenance Instruction
Model LER, LERS, LEZ
LER 100-english page 5
Revision 01
Article No 771073302
Issue 01/2010
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. Thi
s
is valid for the operation as well as for the
standstill of the pump and therefore for all
pos
sible 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 w
ork 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 LER, LERS and LEZ are single-
stage In-line pumps with suction and discharge nozzle
„in-line“ with identical pipe diameter and a common
end-to-end pump-motor-shaft (Mono-Block-Design).
Model LER and LERS:
In-line pump with closed radial impeller in block design
with attached motor.
Model LEZ:
In-line pump with closed radial impeller in block design
with attached motor.
The model LEZ is a twin pump with 2 identical driving
units, common pump casing and an integrated flap
valve on discharge side.
These pumps are not qualified for dangerous
or
inflammable fluids. Not qua
operation in areas subject to explosion hazards.
The permitted application conditions and design
details of the delivered pump are shown in the
attached data sheet and / or the order confirmation
(see Design Coding System in chapter 3.2).
3.1.1 Solids
In general the models LER, LERS and LEZ are suited
to handle a limited number of solids. Whether or not it
can handle a given application largely depends on the
abrasive nature, the concentration and the solid size of
the solids.
It is not allowed to exceed a solid concentration of 25
mg/l up to max. 50 mg/l and a solid size of 0,1 mm up
to max. 0,3 mm. But inside these limits it must be
calculated with higher wear depending on the abrasive
nature of the solids.
3.1.2 Viscosity Limits
In general these models are capable of pumping
viscous liquids. The maximum viscosity limit is appr.
100 cP.
3.1.3 Installation position
The small pump units up to 15 kW motor power can
get installed directly without support foot in the piping,
but for safety reasons the motor arrangement down
respectively the terminal box down is not allowed.
A support foot must be used for big pumps. For the
condition of the base frame see chapter 5.1.
The appropriate sectional drawing of the supplied
pump as well as the complete weight of the pump unit
is shown in the appendix.
3.2 Design Coding System
Due to the coding on data sheet and / or order
confirmation all information regarding der delivered
pump can be found in this Installation, Operation and
Maintenance Instruction, e.g.:
LER 250 - 400 U1 N L 900 4
(0)
(1) (2) (3)
(4) (5) (6)
(7)
Position (0) - Name of the basic Model:
LER - Single unit up to 10 bar / 120 °C
LERS - Single unit up to 16 bar / 150 °C
LEZ - Twin unit up to 10 bar / 120 °C
Position (1) - Suction and discharge nozzle in mm
Position (2) - Nominal impeller diameter in mm
Position (3) - Design of the shaft sealing
Single mechanical seal acc. DIN 24960 l1k /
EN 12756 Form U, unbalanced
Exception: ∅18- and ∅32mm seals are not
acc. DIN 24960 l1k / EN 12756; ∅75mm
PN16 seal is form "B", balanced

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