POWER July 2021 - 13

FOCUS ON O&M
(or springs), allowing for continued
sealing performance as the faces wear
over time during normal operation.
The rotary faces and the spring(s)
Maximum
Oil Level
are affixed to the shaft with two drive
rings. The drive rings create the static
seal at the shaft outer diameter and
translate the rotational force to the
rotary seal faces. Similar to bearing
isolators, no wear is imparted to the
shaft. The stationary faces are captured
within the seal housing by two molded
rubber seats, creating the static seal on
the stationary side.
3. The fluid level within the gearbox must
be maintained below the bottom of the
shaft in a traditional bearing isolator design.
In some gearbox designs, the oil level or
behavior of the oil during running conditions
can result in high splash or a flooded
seal condition. A bearing isolator with an
advanced design can solve that problem.
Courtesy: Garlock Sealing Technologies
Designed for applications and gearboxes
where the internal lubrication level
is higher than the bottom of the shaft,
or where extreme splash conditions
exist, the Flood-Gard shown in Figure
4 combines the benefits of a bearing
isolator with a traditional oil seal. This
model provides the exceptional ingress
protection of a bearing isolator while
also creating an ideal running surface
for the internal oil seal. The Flood-Gard
is available in standard sizes from 1- to
6-inch shaft diameters. It provides consistent,
reliable sealing for even the
most challenging of applications.
Turbine Shaft Seal
Due to the unique location and operation
of tidal turbines, the external shaft
seal must be able to withstand several
application challenges. Pressure differential,
radial and angular misalignment,
as well as corrosion and contamination
all need to be managed in this underwater
environment.
Initially developed for usage with
shipboard propeller shafts, the Syntron
Double Face mechanical seal has proven
to be a solid mechanical shaft seal
solution for seawater pressure boundaries.
The Syntron mechanical seal is a
cartridge-style seal that contains two
opposing carbon and bronze sealing
faces (Figure 5). These faces are loaded
with an internally captured coil spring
July 2021 | POWER
In use, the seal housing is filled with
a lubricating oil and capped. When
submerged, the pressure across the
faces equalizes; therefore, no external
contaminates are driven across
the sealing faces. This allows for extremely
long life with essentially zero
leakage.
The seal housing is manufactured
from machined bronze, eliminating the
corrosion concern that is inherent in
operating in marine environments. The
combination of materials, construction,
and operating parameters make the
Syntron mechanical seal a uniquely wellsuited
solution for the challenging environment
associated
with
equipment
operating offshore. As an additional
benefit, the Syntron is a cartridge-style
seal, and completely rebuildable. This allows
for easy repair and replacement as
needed, while minimizing the total cost
of ownership.
The Syntron mechanical seal is rated
to 150 psi differential pressure, and up
to 400F operating temperature. While
the default materials are bronze, carbon,
and nitrile rubber, the seals can be
manufactured with nearly any elastomer
and housing material.
5. The Syntron Double Face mechanical
seal is a cartridge-style seal with two opposing
carbon and bronze sealing faces. It has
proven to be a good shaft seal solution for
seawater pressure boundaries. Courtesy:
Garlock Sealing Technologies
Neoprene, silicone, and FKM (fluorelastomer)
are common elastomer offerings,
while 316 stainless steel and
Hastelloy are available choices for the
seal housing and internal components.
In addition, the seal can be configured
to act as a fluid coupling. Flow through
the housing is communicated through
vented spring guides to the shaft diameter.
When paired with a hollow shaft,
this allows cooling fluid to be transmitted
through the shaft core to bearings
located further down the shaft. This is
a common solution used in annealing
fan designs.
Leveraging Technology and
Proven Solutions
The necessity and the growth of clean
energy technologies continues to present
unique equipment protection and
sealing challenges. By leveraging both
new sealing technology and mature
proven solutions, matching them with
carefully chosen materials and benefits,
successful and cost-effective solutions
can be configured.
When evaluating these challenging
4. The Garlock Flood-Gard bearing isolator is
an example of an advanced design. It is suitable
for use in situations where the internal
lubrication level in the gearbox is higher than
the bottom of the shaft or when extreme
splash conditions exist.
Sealing Technologies
www.powermag.com
Courtesy: Garlock
environments, the life, performance, and
maintenance cost must all be accounted
for. Often, the total cost of ownership
can be proven to be lowest when using
a more initially expensive sealing solution
like a bearing isolator in favor of an
oil seal. ■
-Dan Naugle is an engineering manager
with Garlock Sealing Technologies, and
Joshua Cavinee is an application and
commercial solutions engineer for the
Klozure Dynamic Sealing Group at
Garlock Sealing Technologies.
13
http://www.powermag.com
POWER July 2021

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