Inlet Pressure; Installation Of The Pump - SeaLand MVX serie Betriebs- Und Installationshandbuch

Operating and installation manual
Power (kW)
2 poles
0,37-0,55 100
0,75-3 60
4-7,5
30
11-22
15
30-55 8
55-200 4
With a motor other than the one supplied as a standard, check the manual for the
maximum number of start-ups per hour.
4.3 Motor data plate
See plate attached to the motor.
4.4 Other plates
Under the data plate, a label indicates the rotation direction of the pump shaft and
the maximum operating temperature of the fluid, for uses other than those set out by
standard EN60335-2-41 (fig.16). For versions MVX 3/6/10/15, a label positioned on
the lower part of the jacket shows the direction of flow (fig.16-A). For versions
MVX 30/45/65 the indication of the direction of flow is shown on the pump base
(fig.16-B).
5 INSTALLATION AND PREPARATION
For the pump to function correctly and to avoid damage to people or things, some
fundamental conditions must be observed, particularly the check of the NPSH and
maximum pressure.
5.1 Checking the NPSH
Check the characteristic curves of the electric pump to evaluate the NPSH factor
(see Fig. 3) and avoid cavitation problems in the case of an excessively high gap
between the pump and the level of the liquid to be drawn or due to an excessively
high temperature (fig.4.B).
The maximum height between the pump and the level of liquid "H" can be calculated
using the following formula:
H = pb x 10.2 – NPSH - Hf - Hv – Hs
bp: Bar pressure or liquid suction pressure [bar].
NPSH: Net positive suction head [m] (see fig.3)
Hf: Friction and entrance head losses in the suction piping [m]
Hv: Steam pressure [m] in relation to the temperature of the liquid (tm) (see fig.4.A)
Hs: Safety margin [m] (minimum 0.5)
If the value calculated is less than "0" the pump should be placed below the liquid level.
Example
bp = 1 bar
Type of pump:
MVX10 Capacity: 9
m3/h
NPSH: 1.5 m
Hf = 2.5 m
Liquid temperature: +50°C
Hv: 1.3 m
H = bp x 10.2 - NPSH - Hf - Hv - Hs [m].
H = 1 x 10.2 – 1.5 – 2.5 – 1.3 – 0.5 = 4.4 [m]
This means that the maximum height between the pump and the level of the liquid to
be sucked is 4.4 metres.
5.2 Checking maximum pressure
Working pressure
It is important to keep the sum of the inlet pressure plus the maximum pressure of the
pump at flow Q=0, always lower than the maximum allowed working pressure (PN).
The PN value is indicated on the nameplate of the pump.
Case 1:
Single standard pump fig.5.A
P1max + P2max <= PN
Case 2:
Standard pump + high pressure pump fig.5.B
Start-ups per hour
4 poles
250
140
60
30
15
8
P1max + P2max + P3max <= PNHP
In this case, refer to the maximum pump pressure HP clearly shown on the additional
label.

Inlet pressure

The inlet pressure must not exceed the limits indicated in the tables in (fig. 2, H1).
5.3 Minimum rated capacity
The function of the pump at a lower level than the minimum nameplate allowed rated
capacity, may cause excessive and detrimental overheating of the pump.
For water temperatures over 40°C, the minimum capacity should be increased
according to the temperature of the liquid (see fig.6).
Please contact our sales and service department for liquids other than water.
WARNING: The pump should never operate dry (without liquid inside)
WARNING: The pump must never operate with the delivery valve closed for
more than 10 seconds.

5.4 Installation of the pump

WARNING: Please observe current accident prevention standards; use
proper protective devices and refer to the regulations, legislation and local
and/or national country codes for water and electricity connections.
WARNING: Before starting work on the electric pump, make sure the electrical
connection has been disconnected from the power supply network and that it
cannot be reconnected accidentally.
WARNING: Ensure all electrical equipment of the pump, motor and monitoring
equipment is earthed. The earth connection should be the last connection to
disconnect from the terminal. Make sure that the earth connection is longer
than the phase connections on both ends of the cable. As extra protection
from lethal electric shocks, install a high sensitivity residual current device
(30mA).
WARNING: DO NOT USE THIS PUMP IN ENVIRONMENTS THAT MAY
CONTAIN INFLAMMABLE/EXPLOSIVE OR CHEMICALLY AGGRESSIVE
DUST OR GAS.
WARNING: The installation of the electric pump is an operation that may prove
complex. It should therefore be carried out by skilled and authorised installers.
5.4.1 Assembly
Guide lines
• Install the electric pump in an accessible area, protected from frost and leaving
sufficient space around the electric pump to allow for its operation and maintenance.
Horizontal assembly is permitted only if the electric pump is properly supported.
Vertical assembly is not permitted with the motor placed on the lower part (see fig.7).
• Check that there are no obstacles blocking the air flow to cool the motor, make sure
there is at least 100 mm of space in front of the fan (Fig.9).
• Any liquid leakages or similar events must be drained and should not flood the
place of installation and/or submerge the unit.
• The electric pump must ALWAYS be firmly fixed to a concrete base or to a metal
structure of size and weight to suit the size and weight of the electric pump; use
screws suitable for the fixing holes provided (see fig.8 dimensions, tightening
torques). To reduce vibrations to a minimum, insert vibration-damping seals
between the pumps and the base.
• Make sure the pump is correctly orientated: The flow arrows shown on the pump
should point in the direction of flow of the connection pipes.
• The connection pipes must be suitable for the operating pressure and the pumped
liquid; between the pipe connections and the pump proper seals should be inserted.
• The pipes should be properly supported (fig.9-1), without resting on the unit. Do
not force the position of the pipes by fixing them, using bolts, to the pump (see fig.
13 for maximum forces and stresses applicable to connections). Flexible hoses or
expansion joints (fig.9-2) are necessary to avoid vibrations being transmitted from
the pump to the piping and vice-versa.
To prevent air bubbles in the suction pipe, arrange it at an inclination of no less than
2%. The diameter of the pipe should not be smaller than the diameter of the suction
vent and should be sealed. If the suction pipe is bigger, install an eccentric reducer
(fig.9-6). If the pump is above the liquid to be sucked (negative suction head pump
fig.9-A) a foot valve should be fitted to the end of the suction pipe (fig.9-3).
• The end of the suction pipe should be sufficiently immersed to prevent air entering
the suction vortex (fig.9-7) when the liquid is at minimum level. Suitably sized gate
valves should be fitted to the suction pipes (fig.9-4) and delivery pipes (fig.9-8) to
regulate flow and to isolate the pump from the circuit in the case of inspection and
maintenance.
• Install a check valve (fig.9-5) to the delivery piping to prevent reflux and water
hammers when the pump is switched off.
• See fig.10: pump connections size and bolt tightening torques.
WARNING: Depending on the temperature of the pumped liquid, the surfaces
of the electric pump may reach high temperatures. If deemed necessary,
provide guards to avoid accidental contact.
5.4.2 Electrical connections
WARNING: Low voltage machines are comprised of rotating, hazardous, live
parts and sometimes also hot surfaces.
WARNING: The installer sees to making the connection in compliance with
current standards in force in the country of installation.
Guide lines
WARNING: The following information is valid for the standard motor supplied
with the pump. If the pump alone is supplied and is coupled with a different
ENGLISH
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