A New Level of Green

Introduction
Throughout the world today, high energy prices pose an
unprecedented profit-robbing threat to every manufacturing
operation, large or small. Left unmanaged and unchecked,
rising energy expenditures can quietly, and quickly, erode
a company’s stability, performance, productivity and,
ultimately, its competitiveness and viability.
Confronted by these rising energy costs, manufacturing
operations around the globe are implementing energymanagement
processes and procedures that seek to:
• Drive product improvements that increase financial
performance
• Control energy expenses by reducing power consumption
without compromising output while simultaneously
increasing production levels
• Increase operational reliability and process integrity by
emphasizing the use of energy-efficient technologies that
also support enhanced mechanical efficiency
• Reduce vulnerability to energy-price volatility
In order to address energy consumption, many areas
around the globe are developing and implementing new
climate and energy policies that have been designed to
create behaviors to moderate energy usage. As an example,
in March 2007, the European Union’s Heads of State
Government announced a series of demanding climate and
energy consumption targets that must be met by 2020.
These are:
• A reduction in EU greenhouse gas emissions of at least
20% below 1990 levels
• Requiring 20% of EU energy consumption to come from
renewable resources
• A 20% reduction in primary energy use compared with
projected levels, to be achieved by improving energy
efficiency
This “climate and energy package” was agreed to by the
European Parliament and Council in December 2008 and
became EU law in June 2009.

Similarly, 2005’s wide-ranging Energy Policy Act in the
United States elevated the profile and increased discussion
of energy use and conservation in the country. Since the
inception of EPAct, there have already been enviable gains
in energy conservation in the industrial sector thanks to
a series of energy-efficiency assessments that were
conducted at more than 400 of the nation’s largest
manufacturing plants.
These assessments showed that it is possible for the
industrial sector to improve its “energy intensity” by 25%
by the end 2017, or an average of 2.5% per year leading up
to that deadline. The key to meeting this goal is instituting
a “systems approach” to energy efficiency and conservation
in manufacturing plants, i.e. turning the focus away from
individual components and, instead, analyzing both the
supply and demand sides of the system as a whole.
However, while it is easy to establish thresholds for
energy consumption, identifying and implementing the
most efficient means to meet those thresholds can be
much more problematic. Using the industrial sector as an
example, since pumps account for anywhere between 27%
and 33% of total electricity used in this sector globally,
improvements in pump-system performance can play an
important role in minimizing energy costs.
The Challenge
At their most basic, poor design and improper system
operation are the root causes of inefficient pumping
systems. As rotating equipment, pumps are subject to
wear, erosion, cavitation and leakage. These problems can
be exacerbated through improper pump selection and
operation. If they are not selected or operated properly,
pumps can waste enormous amounts of energy, as well as
require considerable maintenance.
This pump-selection process can be complicated by the
fact that many different types of pumps can be applicable
in a single operation. And when making the final choice
in type of pump, the list of crucial factors that need to
be taken into account can be daunting: required flow
rate, differential pressure, temperature, viscosity, shear
sensitivity, corrosiveness of the liquid being handled, etc.
In addition, facility managers have a tendency to resort
to lowest-common-denominator thinking when outfitting
their pumping system and just choose to go with oversized
pumps. While installing an oversized pump ensures that
the needs of the system will be met under all operating
conditions, the added energy cost inherent in operating
oversized equipment is generally ignored.
As manufacturers work to align their energy-efficiency
initiatives with their business goals, pump system
improvements will play an increasingly important role in
this effort. Since there is no “one pump fits all” solution,
particular attention to proper pump selection will become
increasingly more important in the effort to select the right
pump that not only will deliver productivity gains, but will
work equally as well at controlling energy consumption.
With this in mind, by virtue of their inherent energyand
mechanically efficient designs, positive displacement
sliding vane pump technologies are uniquely suited to
offer manufacturers immediate, high-value advantages and
solutions in fulfilling their energy-saving initiatives.
The Solution
Of the leading positive displacement technologies, sliding
vane pumps are generally among the most energy efficient.
Significant design advancements have given sliding
vane technology a decisive advantage over gear pumps,
specifically with regard to optimized performance, lowshear
capability, lowest life-cycle cost and best energy
efficiency. For the sliding
vane pump, this is due in
part to the self-adjusting
vane-design feature that
eliminates energy-robbing
slip and promotes high
volumetric efficiency
even after substantial time
in service.
This design makes sliding
vane pumps much more
efficient and desirable for
use than gear pumps. Gear
pumps use the meshing
of gears to pump fluid by
displacement. Because of this style of operation, from day one gear pumps wear
constantly as the pump’s gears mesh together in order
to move fluid. This constant wear increases the internal
clearances between the gear teeth, in the process reducing
flow capacity and volumetric consistency while increasing
the possibility that “slip” will occur. All of these operational
deficiencies result in not only decreased pump performance
and increased maintenance occurrences, but also in wasted
energy use, which can increase costs.
On the other hand, sliding vane pumps operate through
the use of a number of vanes that are free to slide into or
out of slots in the pump rotor when it is driven by the
pump driver. The turning of the pump forces the vanes to
move outward and ride against the inner bore of the pump
casing, in the process forming pumping chambers. As the
rotor revolves, the fluid enters the pumping chambers from
the suction port. The fluid is transported around the pump
casing until it reaches the discharge port where it is forced
out into the discharge piping.
This type of design guarantees fixed displacement volume
with minimal pressure variance, meaning that energywasting
slippage and turbulence are minimized and high
volumetric efficiency is maintained.
The effectiveness of pump-shaft sealing can have a direct
influence on a pump’s power consumption in a variety
of ways:
• By its basic design, the more friction a pump generates,
the more of a “power eater” it will be. From that
standpoint, shaft packing is a less-efficient solution.
• In many cases, a pump’s shaft-sealing system may
need additional cooling, either by a separate fluid (a
mechanical seal flush, for instance) or by diverting part of
the pumped liquid flow (magnetic drive). This additional
cooling requires more energy to work and decreases the
pump’s energy efficiency.
• Most of the shaft-sealing solutions are heat generators.
When choosing a pump-shaft seal, this parameter
must be mastered, especially in a potentially explosive
atmosphere. Therefore, temperature sensors, flow meters
and power monitoring often have to be added, which
generate other energy-consumption concerns.
When shaft packing or a basic mechanical seal cannot
be used for any reason in a pump’s design, the main
alternatives are:
• A double-flushed mechanical seal
• Magnetic drive
• Seal Less Drive
Seal of Approval
Realizing that the most energy-efficient solution to
the pump-shaft sealing challenge is a Seal Less Drive,
Auxerre, France-based Mouvex® has developed the SLP
Series of sliding vane pumps. The SLP Series is a positive
displacement pump that is not based on magnetic drive,
but, rather, a seal-less leak-free design that features no
magnets, no mechanical seals and no packing.
Instead of magnets, the SLP pumps have a double stainlesssteel
bellows that houses an eccentric shaft. This shaft, which is rotated by a crank system, drives the bellows
in a circular movement. This design and operation
addresses each of the concerns of shaft-sealing that are
mentioned above:
• The Mouvex Seal Less drive is needle/roller-bearing
mounted with separate sources of lubrication, meaning
that frictions are reduced to a minimum.
• The pump’s entire flow rate crosses the Seal Less Drive
chamber, meaning that the shaft does not need any
additional cooling, while none of the flow rate is
diverted.
• In most cases, power monitoring is not necessary, with an
optional temperature sensor able to be added in extreme
cases.
The result is a decrease in energy consumption with a
corresponding increase in operational efficiency, all
without added installation complexity. Compared to
magnetic-drive pumps, the SLP pumps create up to a 40%
reduction in absorbed power and up to a 20% higher return
in energy efficiency.
Conclusion
Sliding vane technology is being used worldwide to reduce
energy cost and consumption, and create a more efficient
pumping system. While world-renowned for its ability
to offer the best in increased suction, reduced product
shear and consistent volumetric efficiency, sliding vane
technology has been taken to the next level with the
introduction of Mouvex’s Seal Less Drive technology and its
SLP Series pumps.
Simply put, Mouvex Seal Less Drive technology offers
even more advantages over gear pumps in the quest to
reduce energy consumption and cost without sacrificing
performance and reliability, making them a perfect
positive-displacement pump choice in these increasingly
energy-conscious times.
Paul Cardon is the Industrial Products Manager for Auxerre,
France-based Mouvex®, the leading manufacturer of eccentric disc
pump technology. He can be reached at +33 (0) 633 41 7565 or
Cardon@mouvex.com. Mouvex is an operating company within
Dover Corporation’s Pump Solutions Group (PSG™). PSG is
comprised of six leading pump companies—Wilden®, Blackmer®,
Griswold™, Neptune™, Almatec® and Mouvex®. You can find
more information on Mouvex at www.mouvex.com and at PSG at
www.pumpsg.com.