Design Features
Parr Fixed Bomb and Bucket
Technology
The 6400 Automatic Isoperibol Calorimeter uses a fixed
bomb and bucket design where the bomb and bucket are not removed from the
calorimeter during routine operations. This design concept has made it possible
to offer unique levels of automation for the entire calorimetric determination
not just the data collection and reporting steps. The result of this automation
will save approximately five minutes of operator time per test when compared to
any removable bomb calorimeter.
Oxygen Charging and Release
The fixed bomb and bucket design allow the oxygen supply
to be directed into the head of the bomb at the beginning of each test. The
head of these bombs incorporate a check valve which dynamically seals when the
bomb is pressurized. At the end of the test, the gases in the bomb are
automatically released while the calorimeter is being returned to its starting
temperature.
Fixed Bucket
The bucket in these calorimeters has been designed to
provide smooth circulation over the surface of the vessel. The design also
repeatedly fills the bucket volumetrically. The bomb head closure seals the
bucket at the same time the bomb is closed. This unique design minimizes the
amount of water required for the test as well as permitting rapid, automatic
and repeatable filling for each test. The water heated by the combustion is
automatically drained from the bucket at the conclusion of the test and
replaced with cooling water to bring the bomb and bucket rapidly back down to
the starting temperature for the next test.
Fixed Bomb
The 6400 Calorimeter features the patented closure
design of the Parr Fixed bombs. This design allows the user to seal and lock
the head into the cylinder with simple one sixteenth turn. The main bomb seal
is an o-ring optimized to minimize frictional wear, improving the lifetime of
this seal. At the conclusion of the test the inside surface of the bomb is
washed to remove the products of the combustion from the bomb. The automation
of the bomb washing step eliminates one of the most tedious and time consuming
manual operations required with removable bomb calorimeters. Besides the
elimination of the drudgery of manually washing the bomb, a not so obvious
advantage of the fixed bomb design is that the bomb is always washed as soon as
the final temperature can be determined. Generally, this is within 4-5 minutes
of the time the bomb is fired. This holds to an absolute minimum the time any
acids produced by the combustion can attach to the inner surfaces of the bomb.
This has improved the service life of these bombs in comparison to removable
bombs.
1138 Oxygen Combustion Bomb
The 1138 oxygen bomb is the standard bomb in the 6400
calorimeter. The 1138 Oxygen Bomb has been redesigned to withstand a higher
magnitude of tests. The head is designed with an O-ring groove which is
optimized to minimize frictional wear, in turn improving the lifetime of the
seal. The bomb head is removable for fast sample loading using the patented
Quick Twist-Lock vessel closure design.
The bomb is made from alloy 20; a special niobium
stabilized stainless steel selected for its resistance to the mixed nitric and
sulfuric acids produced during the combustion process. The 1138CL is made from
the halogen resistant Hastelloy G30™. Hastelloy 30™ is an alloy rich
in cobalt and molybdenum and is able to resist the corrosive effects of free
chlorine and halogen acids produced when burning samples with significant
chlorine content. While no alloy will completely resist the corrosive
atmospheres produced when burning samples containing halogen compounds, users
who intend to test these materials are urged to select the 1138CL Bomb.
These bombs are 250 mL in volume and are rated to a
working pressure of 2000 psi. The bombs are hydrostatically tested to 3000 psi
and the sample range is ~1g or 5000 - 8000 calories. The 1138 design provides
some significant advantages over the 1136 design: Its straight wall design
improves bomb rinse recovery
A1450DD Head
Users who wish to achieve maximum through-put with
their 6400 calorimeters will want to purchase a spare A1450DD head for their
calorimeter. This permits the next sample to be completely prepared and
inserted into the bomb as soon as the current test is concluded.
Control Chart
Capabilities
A control chart is a graphical tool which can assist
the user in determining whether or not their process is in control. Many
standard methods will dictate that a reference sample be measured periodically
and the results plotted on a graph. Limits for acceptable values are defined
and the process is assumed to be in control as long as the results stay within
these limits. Since results are expected to scatter with a normal distribution
within established limits, systematic trends or patterns in the data plots may
also be an early warning of problems. The 6400 calorimeter provides the user
with the ability to instantaneously plot and view standard results with user
defined warning and control limits.
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