Parr Instrument 6772 - Manual (Page 52)

6772
Calorimetric Thermometer Instruction Manual
6-5
e1 = [((25)(.0709)) – (2)(1)(.6238)] 14.1
e1 = [(1.7725) – (1.2476)] 14.1
e1 = [.5249] 14.1
e1 = 7.40109 calories
When the Acid Correction is set to Fixed Total the value is considered a final value
and the operator is not prompted for an acid value when reporting the results.
Entered Total: The Acid Correction represents the total base required to titrate the
bomb washings (in milliliters). This includes both nitric and sulfuric acid. The
correction is entered by the operator when reporting the results.
The calculation is the same as the Fixed Total above. The value listed on the Acid
Correction button is used for preliminary calculations. When finalizing the report the
operator will be prompted for the acid value.
Calculated HNO3: In ASTM D5865 there are provisions for calculating the nitric acid
contribution.
For test samples that contain no nitrogen, the quantity of nitric acid formed during the
combustion process is a function of the volume of the bomb, the oxygen filling
pressure, and the quantity of energy released.
For the calculated nitric acid method:
e1 = (nitric acid factor/1000)(Energy Equivalent)(corrected temperature rise)
Example: For a test run with energy equivalent of 2425.0729 and a corrected
temperature rise of 2.6348 would result:
e1 = (1.58/1000)(2425.0729)(2.6348)
e1 = 10.0955 calories
The calculated nitric acid method can be applied to samples containing up to 2%
nitrogen without introducing a significant error in the resulting heat of combustion
value.
Note:
The values entered into the test report appear as entered in the report. Values for e
1
, e
2
and e
3
are calculated and used as energy corrections in accordance with the formulas
and settings given above. The formulas used above to arrive at e
1
or e
2
are not the
same as the formulas used for e
1
and e
2
which appear in most ASTM bomb calorimetric
procedures. However, the sum of e
1
and e
2
, above, is equal to the sum of the ASTM
treatment of e
1
and e
2.