Parr Instrument 6400 - Manual (Page 58)

6400
Calorimeter Instruction Manual
6-3
Manual Entry
During the reporting process, the controller will prompt the user to enter the following
values:
• Fuse
Correction Key in the Fuse/Heat Wire Correction and press the ENTER
key. The default setting for this value is to be entered in
calories.
• Acid
Correction Key in the Acid Correction and press the ENTER key. The
default setting for this value is to be entered in milliliters of
standard alkali required to titrate total acid or calories.
• Sulfur Correction
Key in the Sulfur Correction and press the ENTER key. The
default setting for this value is to be entered as percent sulfur
in the sample.
Note: If the Spiking Correction is used, a spiking correction must be
entered before obtaining a Final Report. After the last entry has been
made, the Calorimeter will automatically produce a Final Report. If values
for these corrections are not available, the operator can use the SKIP key
to bypass any of the corrections, however, a Final Report will not be
printed until an entry is made for fuse, acid and sulfur.
Fixed Corrections
In many cases, fixed values for fuse and acid can be used without introducing a
significant error since the corrections are both relatively small and constant. Fixed sulfur
corrections can also be used whenever a series of samples will be tested with a
reasonably constant sulfur content. Any value set-up as a fixed correction will be
automatically applied and the calorimeter will not prompt the user for this value.
Definitions
Total acid is the amount of base required to titrate the bomb
washings (milliliters).
Nitric acid is that portion of the total acid in the bomb washings that
result when the nitrogen in the air that is trapped in the
bomb is burned at high pressure. Since this nitric acid
does not result from the sample, and the combustion
conditions are reasonably constant from test to test, the
amount of nitric acid formed is also constant.
Acid multiplier is multiplied by the user entered acid value to arrive at the
number of milliequivalents of acid. This value is usually
the concentration (normality) of the base in equivalents per
liter.
Percent sulfur is the concentration of sulfur in the sample (weight %).
Molecular weight of sulfur is 32.06.
Equivalent weight of sulfur in H
2
SO
4
is 16.03 (one half of the molecular
weight).
Heat of formation of nitric acid is 14.1 calories / milliequivalent.