12 B ULK D ISTRIBUTOR
Components
November/December 2019
Loading rack concerns
David Morrow explains the
advantage of next-generation
bottom-loading API couplers
W
ithout doubt, the piece of equipment
that is the true workhorse in any type
of liquid storage terminal is the bottom-
loading API coupler that serves as the conduit
between the loading arms and the tank truck.
In high volume terminals, it is not unusual for
these couplers to be connected and disconnected
more than 50 times a day. That is 50-plus head-on
collisions between the coupler and adapter, which
translate into a huge amount of use and abuse.
Over the years, the design and operation of API
couplers (also known as ‘load heads’) have evolved
to the point that they can reliably withstand the
abuse that they are subjected to on a daily basis.
6 loading rack concerns
With that in mind, there are six areas of concern
that operators must be on the lookout for and
remedy if the efficiency of their couplers, and their
overall loading-rack operations, are to meet
expected operational standards:
Seal Wear. If a coupler is experiencing leaks after
it is connected to the delivery vehicle, the most
likely culprit is a worn seal. Specifically, the nose
seal, which is the primary link between the truck
and the coupler, may need to be replaced.
Terminal operators must monitor this seal
constantly and replace it at any sign of wear, lest a
leak point develop.
Loading arm adjustment. Another potential
cause of leaks could be the positioning of the
loading arms. Ideally, the loading arms should be
balanced at the truck adapter’s height of 30-35 ins
off grade. If the arms are positioned either lower
or higher than recommended, undue stress on the
loading system can result, which can lead to the
creation of leak paths.
Weak or broken wave springs. While the first
two conditions will generally result in minor leaks,
a weak or broken wave spring in the coupler can
lead to a significant product loss. The wave spring
is critical in producing effective coupler operation
because it creates seal compression when it is
connected to the truck adaptor. Closely monitoring
the performance of the wave spring is important
because if it were to break, resulting in insufficient
seal compression, the coupler will need to be
taken out of service. And while it is replaced, that
downtime will compromise fuel-delivery schedules.
Thermal expansion. Most couplers are rated for
use at 75-80 psi (5.2-5.5 bar), but they can
experience much higher pressures if thermal reliefs
are not in place and functioning properly. In fact,
extreme thermal expansion can create pressures in
excess of 300-500 psi (20.7-34.5 bar). At pressures
this high, the coupler could be at risk of a
catastrophic failure leading to extreme loss of
product. If the technician is having difficulty
opening or closing the coupler handle, this may be
a sign of thermal-expansion issues.
Extreme temperatures. Regardless of the
ambient temperature, the terminal must keep
product flowing. This can become more difficult
to do when extreme temperatures are
experienced. This is especially true when extreme
cold takes hold. Most couplers are designed to
operate effectively at temperatures as low as
0degF (-18degC), but the seals may become
compromised – leading to product leaks – if the
temperature gets much lower. In this case, the
terminal operator should consider employing one
The Lynx bottom-loading coupler from OPW combines all of the best features of API couplers in one device
of the new cold-weather couplers that can
operate in temperatures as low as -40degF
(-40degC) that have begun to enter the market.
Dirt and debris build-up. Operators should
regularly check the latches and cams on their
couplers for any build-up of dirt and debris. If any
contaminants are allowed to collect in the coupler,
the cams may catch and create an imperfect seal,
which can result in leaks. Extra attention should
be paid to this area in the winter months when
road salt and sand can collect on the face of
couplers.
To the rescue
Knowing how important it is to optimise loading
rack efficiency, manufacturers of bottom-loading
API couplers have worked on developing
advanced technologies that can meet the
demands of high-volume liquid-transfer activities
around the world. One example is the Lynx
Bottom-Loading Coupler from OPW Engineered
Systems. This advanced coupler model combines
all of the best features of API couplers in one
device that has been designed to provide a
superior and effortless bottom loading experience.
The fulcrum of advanced API coupler design is
the use of a unique U-pin that allows assembly
and disassembly of the coupler in no more than 30
seconds. Other key features of the advanced
design include: in-field replacement of the main
seals, on or off the arm; wave-spring design that
will last three times longer than competitive
models; durable stainless-steel collar and hard
anodised aluminium body for increased service
durability and life; four ‘true interlocking’ stainless-
steel latches that ensure secure coupling and
maximum product containment; A wide variety of
seal materials, including fluorocarbon, Buna-N
(nitrile) and FFKM; short 5.9ins (110mm) and long
7.8ins (200mm) operating-handle lengths. Finally,
an ergonomic operating handle and carry loop
puts less physical strain on users.
David Morrow is director of product management
for OPW Engineered Systems.
www.opw-es.com