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 294 of 460

FED-STD-791D

6.3 Prepare a solution of the cutting fluid by placing 190 mL of distilled water

and 10 mL of the cutting fluid in a 250-mL graduated cylinder. Stopper the graduated

cylinder and invert it several times. Continue inverting the graduate until a uniform

mixture is obtained.

6.4 Place 50 mL of the cutting fluid solution in each of the four test tubes. Mark

the fluid level on the outside of each test tube and maintain this level by the addition of

distilled water during the course of this test.

6.5 Fill the bubble tower with the sodium hydroxide solution and connect the

tower, through the air pressure regulator, to the source of compressed air by means of the

rubber tubing.

6.6 Connect each length of glass tubing, by means of rubber tubing and an

appropriate manifold or series of Y-tubes, to the discharge outlet of the bubble tower.

Place a screw type pinch clamp on each piece of rubber tubing leading to the glass tubes.

6.7 Insert each glass tube to the bottom of a test tube and adjust the air flow into

each tube to produce approximately one bubble per second by means of the air pressure

regulator and pinch clamps.

6.8 Permit the air to bubble into the tubes at room temperature 24�  3�C (75� 

5�F) for a period of 48 h.

6.9 At the end of the test period, remove the metal strips from the test tubes. If

the cutting fluid under test is a soluble oil type, wash the metal strips in

1,1,1-trichloroethane and permit them to air dry. If the cutting fluid under test is a

chemical solution type, wash the metal strips in distilled water and blot them dry with

facial tissue.

6.10 Remove the duplicate metal strips from the bottle of normal hexane and

permit them to air dry. Examine the exposed and duplicate metal strips under 5X

magnification for conformance with the specification requirement.

7. CALCULATIONS

7.1 This section is not applicable to the test procedure.

8. REPORTING

8.1 Comply with specification requirement.

9. PRECISION

9.1 Precision data have not been developed for this method.

Method Prepared By:

Army - AR � 1986

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