FED-STD-791D
7. CALCULATIONS
7.1 Compute the viscosity, carbon residue, and neutralization number work
values of the test oil. The values shall be computed and reported as follows:
5 (A - B)
a. Viscosity work value = 1.00 -
B
where:
A = viscosity after endurance test, SUS
B = viscosity before endurance test, SUS
Viscosity work value is determined by averaging the three values obtained from
individual calculations based on viscosity data at 38C (100F), 54C (130F), and
99C (210F).
0.80 - D
b. Carbon residue work value =
0.80 - C
where:
C = carbon residue before endurance test.
D = carbon residue after endurance test.
1.01 - F
c. Total acid number work value =
1.01 - E
where:
E = neutralization number before endurance test.
F = neutralization number after endurance test.
d. Average the work values obtained and this value is called the work factor.
8. REPORTING
8.1 Report the three work values and the work factor.
9. PRECISION
9.1 Repeatability. The appearance of the test bearing is of primary importance.
A quantitative rating or comparison scale for this characteristic has not yet been
established. There has, however been no difficulty in reaching conclusions with respect
to excellent, borderline or failing oils. Experience to date indicates that duplicate work
factor values can be expected not to differ by more than 0.02 units from the mean.
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