18
A.0500.251 – IM-TL/13.00 EN (08/2009)
Vacuum table
Atmospheric
pressure
For conditions with
positive suction head
Absolute
vacuum
8. When installing a pump complete with drive motor and baseplate the following
guidelines must be observed:
a) The most suitable drive for the TopLobe pumps is to use a motor with direct
coupling. Please contact your local distributor if using some other method.
b) Flexible couplings must always be used and aligned correctly within the limits
recommended by the coupling manufacturer. Turn the shaft at least one full rota-
tion to control the alignment of the coupling and that the shaft rotates smoothly.
c) Couplings must always be enclosed in a suitable guard to prevent contact with
rotating parts which could cause personal injury. Such guards must be of suitable
material - see point d - and be of sufficiently rigid design to prevent contact with
the rotating parts during normal operation.
d) When installing pump sets in flammable or explosive environments or for
handling flammable or explosive media, special consideration must be given not
only regarding the security of the drive unit enclosure, but also for the materials
used both in couplings and guards to eliminate the risk of explosion.
The NPSH available from the system must always exceed the NPSH required by the
pump. If the following guidelines are observed it should ensure the best possible suction
conditions.
The suction line should have at least the same diametre as the pump connections.
•
The suction line should be as short as possible.
•
Use a minimum of bends, tees and pipework restrictions.
•
The calculations to determine the NPSH available from the system should be carried
•
out for the worst condition, see vacuum table.
If a filter is used on the suction pipe, check pressure drop at the actual flow. This is
•
important to avoid cavitation which can damage the pump.
Please contact your loal distributor if you require information on the pump or system
NPSH characteristics.
For suction lift or
vacuum conditions
NPSH available
Suction lift
or vacuum
Suction line
friction loss
Vapour
pressure
≅
10 m
water
column
Suction
head
NPSH available
Suction line
friction loss
Vapour
pressure