Chemical Engineering August 2022 - 40

peristaltic pumps are larger than many
other technologies, which means
they require more operating space.
Also, when or if the pump's hoses fail,
a catastrophic leak can occur, and
hose degradation during operation
can compromise the integrity of more
sensitive liquids.
On the other hand, two of the
FIGURE 3. Magnetically driven internal-gear pumps
have a simple design with fewer components than
other pump types, resulting in streamlined maintenance
and reduced downtime
pipe). There are also some shortcomings:
their flow and pressure capacities
are narrower than some other PD
pump technologies; they create pulsation
in the liquid path; and because
air is expensive, they can be costly
to operate, especially when used in
continuous-duty applications.
Peristaltic pumps are suitable for
handling thick slurries and liquids with
large solids. They deliver flowrate consistency
despite changes in pressure,
but their flowrate range is limited, and
pulsating flow can occur, which will
make it difficult to dial in a specific
flowrate. From a footprint standpoint,
lesser-known seal-less PD pump
technologies that feature a mag-drive
design are sliding-vane and internalgear
pumps. The basic advantages of
these mag-drive pumps are that they
are electrically driven, so there is no
need for compressed air; they have
a wide and consistent flowrate range;
they create no pulsation in the liquid;
they operate well at higher temperatures;
they are immune to changes in
liquid viscosity or pressure; and they
are truly self-priming, meaning they
can prime while being fully dry, right
out of the box. The following sections
take a closer look at the specific advantages
of these technologies.
Sliding-vane pumps
Sliding-vane technology (Figure 2)
self-compensates for wear, sustaining
new performance throughout
the pump's operational life. Vane
pumps uniquely allow a wide viscosity
and pressure range, and are well
suited for challenging applications,
such as those with suspended solids,
varying system pressure, zero
NPSHa, liquid-vapor mix and regular
dry-run operation.
Reliability. Mag-drive sliding vane
technology allows for extended and
expected dry-run; high suspendedsolids
levels (up to 20% in some
cases); zero-NPSH-required performance
that is ideal for challenging
pump inlet conditions, including
with liquids featuring up to 20%
vapor or air content; and provides
uptime without the use of currentmonitoring
systems.
Functionality. The mag-drive sliding
vane technology can achieve suction
lift of more than 25 ft (7.6 m) without
the need to pre-prime the system;
provides bi-directional flow; and can
line strip to reduce product waste
during or after production runs.
Flexibility. The mag-drive slidingvane
technology provides a wide
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Chemical Engineering August 2022

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