Parr Instrument 6400 - Manual (Page 21)

Operation
6400 3
w w w . p a r r i n s t . c o m 19
Programming
The program in the 6400 Calorimeter can be exten-
sively modified to tailor the unit to a wide variety
of operating conditions, reporting units, laboratory
techniques, available accessories and communica-
tion modes. In addition, the calculations, thermo-
chemical corrections and reporting modes can be
modified to conform to a number of standard test
methods and procedures. Numerous provisions are
included to permit the use of other reagent concen-
trations, techniques, combustion aids and short cuts
appropriate for the user’s work.
Note: Changes to the program are made
by use of the menu structure. Any of these
items can be individually entered at any time
to revise the operating program.
Default Settings
Units are pre programmed with default settings.
See Table 15-1 for a listing of the factory default
settings. A more in-depth explanation of these pa-
rameters is found on the corresponding parameter
group help pages. These default settings remain
in effect until changed by the user. Should the user
ever wish to return to the factory default settings, go
to the Program Info and Control Menu, User/Factory
Settings, touch Reload Factory Default Settings and
YES. Non-volatile memory is provided to retain any
and all operator initiated program changes; even
if power is interrupted or the unit is turned off. If
the unit experiences an intentional or unintentional
“Cold Restart”, the controller will return to the last
known settings.
The default parameters of the 6400 Calorimeter can
be changed to guarantee that the calorimeter, when
cold restarted, will always be in the desired configu-
ration before beginning a series of tests. Users who
wish to permanently revise their default settings
may do so using the following procedure:
• Establish the operating parameters to be stored
as the user default settings.
• Go to the Program Info and Control Menu, User/
Factory Settings, User Setup ID, and enter the
desired User Setup ID.
• Select Save User Default Settings
To re-load the user default setting, go to the Pro-
gram Info and Control Page, User/Factory Settings,
Re-load User Default Settings, and YES.
Sample Preparation
Sample Size
To stay within safe limits, the bomb should never be
charged with a sample which will release more than
8000 calories when burned in oxygen. The initial
oxygen pressure is set at 30 atmospheres (450 psig).
This generally limits the mass of the combustible
charge (sample plus benzoic acid, gelatin, firing oil
or any combustion aid) to not more than 1.1 grams.
To avoid damage to the bomb and calorimeter,
and possible injury to the operator, it should be
a standing rule in each laboratory that the bomb
must never be charged with more than 1.5 grams of
combustible material.
When starting tests with new or unfamiliar materi-
als, it is always best to use samples of less than 0.7
grams with the possibility of increasing the amount if
preliminary tests indicate no abnormal behavior and
the sample will not exceed the 8000 calorie limit.
Samples containing sulfur should contain no more
than 50 mg of sulfur and liberate at least 5000
calories.
Samples containing chlorine should be spiked to
insure that sample contains no more than 100 mg of
chlorine and liberates at least 5000 calories
Particle Size and Moisture Content
Solid samples burn best in an oxygen bomb when
reduced to 60 mesh, or smaller, and compressed
into a pellet with a 2811 Parr Pellet Press. Large par-
ticles may not burn completely and small particles
are easily swept out of the capsule by turbulent
gases during rapid combustion.
Note: Particle size is important because it
influences the reaction rate. Compression
into a pellet is recommended because the
pressure developed during combustion can
be reduced as much as 40% when compared
to the combustion of the material in the
powder form. In addition to giving controlled
burn rates, the formation of pellets from
sample material keeps the sample in the fuel
capsule during combustion.
Materials, such as coal, burn well in the as-received
or air-dry condition, but do not burn completely dry
samples. A certain amount of moisture is desirable
in order to control the burning rate. Moisture con-
tent up to 20% can be tolerated in many cases, but
the optimum moisture is best determined by trial