Energy consumption of a pump with a variable-speed motor is about 90% less than that with a fixed-speed pump.
By Peter Coffey
Vacuum is such a common utility for most labs and is an important influence on the achievement of sustainability objectives.
Studies indicate that vacuum pumps can represent 15% or more of the plug loads in labs. If
you can significantly reduce energy use by vacuum pumps, you can make an important dent
in total lab building plug loads. Beyond that,
vacuum generation can also affect water use,
resource utilization, adaptability and lab building emissions. And, of course, we want to achieve
sustainability gains while enhancing the science
that happens in the labs and lowering capital and
operating costs. Tall order…but possible.
Let’s briefly review the sustainability impacts
of traditional vacuum technologies. Water jet
aspirators are familiar; attached to a sink faucet,
they rely on high water flows to create vacuum.
While inexpensive initially, these devices consume vast amounts of water. Operating just ten
hours a week, each unit can waste and contaminate 50,000 gallons of water per year, leading to
long-term water and water treatment costs. For
these reasons, once-through water aspirators
are both expensive and not permitted under
Central vacuum systems provide convenient
bench vacuum, but the vacuum is sufficient
only for filtration and aspiration tasks, so many
supplemental pumps are often needed for evaporative work from gel dryers to rotovaps. These
building-wide systems are also inflexible; only
by oversizing of pumps, ballast tanks and piping can adaptability to possible future needs be
ensured. Further, many central vacuum systems
either operate continuously or rely on technologies that are susceptible to corrosion from lab
vapors, leading to high energy and service costs.
Individual pumps are the third common
option, and have a lot of advantages. They can
be perfectly matched to the scientific needs and
operated only when vacuum is needed. That
conserves energy and extends service cycles.
Oil-free pumps can be equipped with accessories that capture vapors coming off vacuum
applications, reducing discharge to the atmosphere through fume hoods. One pump per
scientist can be an inefficient use of resources,
however, when used infrequently.
Some innovative approaches to vacuum,
such as variable-speed pumps and multi-user
vacuum networks, offer significant opportunities to advance sustainability goals.
Variable-speed vacuum pumps take advan-
tage of the fact that it takes a lot more power
to create vacuum than to sustain it once estab-
lished. The variable-speed unit pumps quickly
to establish the vacuum, then ramps back to
pump more slowly—just enough to maintain
the vacuum level. The benefit: 70% to 90%
energy savings and better process control than
conventional pumps. These oil-free pumps can
also condense and collect for proper disposal
90% or more of the residual vapors coming off
vacuum applications, without dry ice or liquid
nitrogen, reducing building emissions.
Local vacuum networks also offer significant
sustainability advantages. With local vacuum
networks, a single, compact pump within a lab
provides vacuum to multiple users. By incorporating specialized vacuum turrets, which
control airflow without the large pumps or ballast tanks of a central vacuum system, a small
pump can supply stable vacuum as deep as 1.5
Torr ( 29.86 in. Hg) to up to 16 bench ports in
a lab—vacuum deep enough to support most
evaporative work without dedicated individual
pumps. Local network pumps produce vacuum
on demand. Since they can replace both central vacuum and many individual pumps, the
approach saves energy, bench space and maintenance. Network layouts are adaptable with
simple tools as scientific needs change. The
network pump can also condense and collect
waste vapors from vacuum applications on the
network, reducing emissions to the atmosphere.
The modularity permits use in both new con-
struction and renovations, helping to extend
the useful life of existing buildings.
The ultimate in energy-conserving vacuum
supply arises when using variable-speed vacu-
um pumps to support a local vacuum network.
Energy savings routinely amount to 90% with
such a configuration compared with central
vacuum or individual fixed-speed pumps, while
retaining the sustainability advantages of vari-
able-speed pumps and multi-user networks.
In short, by adopting innovative vacuum
approaches, the possibility exists to reduce
energy consumption for vacuum supply by as
much as 90%; use virtually no water; eliminate
resource-intensive, building-wide vacuum systems and replace them with adaptable technologies that can be changed as the scientific needs
of the building change. These approaches can
reduce building emissions and support research
with superior vacuum that also conserves lab
and bench space, as well as researcher time.
Importantly, these sustainability objectives can
often be achieved while lowering capital and
lifetime operating costs.
Peter Coffey is the VP of Marketing at VacuuBrand Inc. firstname.lastname@example.org. VacuuBrand specializes in resource-efficient vacuum
solutions of labs, including multi-user vacuum,
variable-speed pumps and waste-vapor capture