FED-STD-791D
TABLE I. Standard operating conditions.
Condition
Value
Coking-tube temperature, C (F)
(590 5)
310 2.5
"Oil-in" temperature, C (F)
149 2.5
(300 5)
Air temperature (test section), C (F)
48.9 2.5
(120 5)
300 5
Oil flow, mL/min
Air flow, mL/min
300 5
Oil level (aerated), below top of
3.81 0.32
(1-1/2 1/8)
coking-head glass, cm (in)
6.15 Using the standard operating condition listed in Table I, conduct a 12-hour
(10 min) run on the test oil used in adjusting the system (see 6.14). Perform the test as
follows:
a. While the system is hot, adjust the oil level in the oil filter tube to about 3.8 cm
(1-1/2 in) below the oil level mark on the tube (to allow for an increase in
volume as a result of aeration).
b. Start the oil flow at 300 mL/min.
c. Adjust the air flow to 300 mL/min.
d. Fill the oil feeder flask completely with test oil, stopper tightly, and install in oil
filler tube.
NOTE 5:
The feeder flask must be full at the start of the test run (to minimize oil
ejection due to air expansion). It is helpful to heat flask and oil to 54.4C
(130F) prior to its installation. The stopper on the flask must be tight to
avoid air leakage after installation.
e. Set coking tube temperature control to 310C (590F).
f. Check setting of "oil-in" temperature control for 149C (300F).
g. As soon as "oil-in" temperature reaches 138C (280F) start timing the test
period by setting the timer (4, see Figure 1) on 12 h. If apparatus is so
equipped, set watt-hour meter (5) to zero. Read and record all temperatures and
pressures.
h. Adjust height of oil-filler assembly to maintain the aerated oil level in the
coking head at the mark on the coking-head glass to within 0.32 cm (1/8 in).
Maintain this level for duration of test. Keep valve (29) open for duration of
test.
i. Check the operation of the coking-tube temperature control, and adjust to hold
310 2.5C (590 5F) coking-tube temperature. If the control does not hold
within these limits, adjustment of the band width is required. (See instruction
manual for the control).
j. Check "oil-in" temperature control, and adjust to hold 149 2.5C (300
5F) "oil-in" temperature. If the "oil-in" control does not hold within prescribed
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