FED-STD-791 Lubricants, Liquid Fuels, And Related Products, Testing Method OfThis test method standard is composed of standard test methods for sampling, inspecting and testing lubricants, liquid fuels and related products. It is issued pursuant to the Federal Property and Administration Services Act of 1949, as amended and its application to the purchase of commodities referred to herein is mandatory on all Federal agencies.

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'�NOTE:This draft dated 15 April 2006' by DasH - Page 215 of 460

FED-STD-791D

f. Determine the color of the oil by ASTM D 1500.

6.13 Process the water layer from the centrifuge tube and the washings as follows:

a. Combine the water from the centrifuge tube with the water from the washings.

b. Determine the acid number of this water (based upon the original weight of the

oil sample) by ASTM D 974.

6.14 Determine the weight of any insolubles remaining in the centrifuge tube as

follows:

a. Add 50 mL of new test oil to the tube, and centrifuge until the oil is clear.

b. Carefully decant the oil, and dry the tube in the oven to remove all traces of

water.

c. Again wash the contents of the tube with new test oil, centrifuge until clear, and

decant the oil.

d. Wash the residue with petroleum ether (to remove the remaining oil); centrifuge,

decant, and dry the tube in the oven.

e. Determine the increase in weight of the tube to within 0.2 mg.

6.15 Calculate the percentage (by weight) of the insolubles in the oil (see 7.1).

6.16 Remove the copper strip from the fluid container, and process it as follows:

a. Wash the strip with petroleum ether, warm n-hexane, and warm

1,1,1-trichloroethane and allow it to dry in air. See note 1 (see 6.6) and note 2.

NOTE 2:

Caution. 1,1,1-Trichloroethane is toxic. Do not permit it to come in

contact with the skin or breathe its fumes. Use only in well ventilated

area.

b. Determine the weight change of the strip to within 0.2 mg. Calculate the change

in weight per square centimeter of total surface.

c. Examine the strip under 20X magnification, and record any visible signs of

corrosion.

d. Again wash the strip with petroleum ether, warm n-hexane, and warm

1,1,1-trichloroethane. While washing, scrub the strip with the short-bristled

brush. Allow the strip to air dry, and reweigh to within 0.2 mg.

e. Repeat this washing until the strip reaches a constant weight.

f. Determine the weight loss of the strip (after brushing) from its originally

polished condition.

g. Calculate the loss in weight per square centimeter of total surface.

7. CALCULATIONS

7.1 Calculate the percentage (by weight) of the insolubles in the oil as follows:

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