Flowserve LNN - Manual (Page 13)

LNN, LNNV, LNNC USER INSTRUCTIONS ENGLISH 71569074 06-14
Page 13 of 56
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3.4.3 Energy efficient operation of pumps
The pump supplied will have been selected from
Flowserve’s extensive product line to have optimum
efficiency for the application. If supplied with an electric
motor then the motor will meet or exceed current
legislation for motor efficiency. However it is the way
the pump is operated which has the greatest impact on
the amount and cost of energy used during the
operating life of the pump. The following are key points
in achieving minimum operating cost for the equipment:

Design the pipe system for minimum friction
losses

Ensure that the control system switches off the
pump when not required

In a multi-pump system run the minimum number
of pumps

Try to avoid systems which by-pass excess flow

Avoid as far as possible controlling pump flow by
throttle valves

When commissioned, check that the pump
operates at the duty specified to Flowserve

If it has been found that the pump head and flow
exceed that required, trim the pump impeller
diameter

Ensure that the pump is operating with sufficient
NPSH available

Use variable speed drives for systems which
require variable flow. A VFD for an induction
motor is a particularly effective way of achieving
speed variation and energy/cost reduction

Notes for VFD usage:
o Make sure that the motor is compatible with VFD
o Do not over-speed the pump without checking
the power capability with Flowserve
o On systems with high static head, speed
reduction is limited. Avoid running the pump at
a speed which gives low or zero flow
o Do not run at a low speed and flow rate which
lets solids settle out of suspension in the pipe
work
o Do not use a VFD for a fixed flow requirement;
it will introduce power losses

Select high efficiency motors

If replacing a standard motor with a high efficiency
motor it will run faster and the pump could take
more power. Reduce the impeller diameter to
achieve energy reduction

If the pump system pipe work or equipment is
changed or process duty is changed, check that
the pump is still correctly sized

Periodically check that the pipe system has not
become corroded or blocked

Periodically check that the pump is operating at
the flow, head and power expected and that the
efficiency has not reduced with erosion or
corrosion damage
4 INSTALLATION
Equipment operated in hazardous locations
must comply with the relevant explosion protection
regulations. See section 1.6.4, Products used in
potentially explosive atmospheres.
4.1 Location
The pump should be located to allow room for
access, ventilation, maintenance and inspection with
ample headroom for lifting and should be as close as
practicable to the supply of liquid to be pumped.
Refer to the general arrangement drawing for the
pump set.
4.2 Part assemblies
Motors may be supplied loose on LNNV pumps,
typically on motor frame sizes 400 and above. It is
the responsibility of the installer to ensure that the
motor is assembled to the pump and lined up as
detailed in section 4.5.2, Alignment methods.
4.3 Foundation
There are many methods of installing
pump units to their foundations. The correct method
depends on the size of the pump unit, its location and
noise vibration limitations. Non-compliance with the
provision of correct foundation and installation may
lead to failure of the pump and, as such, would be
outside the terms of the warranty.
Ensure the following are met:
a) The baseplate should be mounted onto a firm
foundation, either an appropriate thickness of
quality concrete or sturdy steel framework. (It
should NOT be distorted or pulled down onto the
surface of the foundation, but should be
supported to maintain the original alignment.)
b) Install the baseplate onto packing pieces evenly
spaced and adjacent to foundation bolts.
c) Level with shims between baseplate and packing
pieces.