ASTM D4636 test method for corrosiveness and oxidation stability of oils
ASTM D4636 Standard Test Method for Corrosiveness and Oxidation Stability of Hydraulic Oils, Aircraft Turbine Engine Lubricants, and Other Highly Refined Oils
5. Apparatus
5.1 The main apparatus consists of the following items of standard wall borosilicate glassware as shown in Figs. 1-5:
5.1.1 Main Sample Tube (Fig. 1).

5.1.2 Sample Tube Head (Fig. 2).

5.1.3 Air Tube5 (Fig. 3).

5.1.4 Condenser, Allihn Type (Fig. 4).

5.1.5 Condenser, Allihn Type, Fig. 4 with 71/60 joint.

5.1.6 Assembled Apparatus (Fig. 5).

5.2 Additional glassware items and assembly accessories needed are:
5.2.1 Spacers (for Metal Specimen), of borosilicate glass, standard wall, 9-mm outside diameter, 6-mm length.

5.2.2 Oil Sampling Tube, Borosilicate Glass, 4-mm outside diameter, with sampling end approximately 600 mm to reach into the main sample tube. The tube is bent U-shape with exit end fitted by a one-hole stopper to a 25-mL filtering flask. The exit end may be any convenient length.

5.2.3 Adapter, polytetrafluoroethylene for 10/18 joint for sealing of air tube to sample tube head.

5.3 Other items and equipment are:
5.3.1 Heating Bath, constant temperature within +/-0.5°C (+/-1°F) of test temperature with an immersion depth of 250 +/- 20 mm. Oil baths or aluminum block baths are recommended, but above 220°C (428°F), use aluminum block bath or other similar non-oil-type heating medium. (Warning - There are exposed hot surfaces on apparatus. Avoid contact with exposed skin by use of protective equipment as required.)

5.3.2 Hood, ventilation to adequately remove fumes during heating.

5.3.3 Air Supply, free of reactive contaminants. For dry air, dew point is -68°C (-90°F) maximum; for moist air, moisture is 10 +/- 1 mg water/L air, standard conditions of 21°C (70°F)/105 kPa (1 atm).

5.3.4 Flowmeter, capable of measuring 10 +/- 1 L/h at same standard conditions as in 5.3.3.

5.3.5 Balance, analytical, sensitivity 0.1 mg.

5.3.6 Balance, Laboratory, 2500-g capacity, 0.1-g sensitivity.

5.3.7 Centrifuge, capable of relative force of 840 +/- 40 relative centrifugal force at the tip of the tubes.

5.3.8 Centrifuge Tubes, Test Method D91, cone-shaped, 100 mL.

5.3.9 Microscope, with 20-diameter magnification.

5.3.10 Assembly Fixture, wood (slotted to hold metal squares for tying with cord) as shown in Fig. 6.

5.3.11 Cord or Wire, for tying metal squares together. Suitable cord should be lightweight of cleaned linen, cotton, nylon, or ceramic fiber; suitable wire is nichrome or tantalum.

5.3.12 When air must be conditioned, there is need for an air drier or humidifier. The method used is optional provided the air characteristics of 5.3.3 are attained. For drying, a satisfactory method is the use of a glass column containing 8-mesh anhydrous calcium sulfate with a column diameter such that velocity of air does not exceed 1.2 m/min. For humidifying, a satisfactory device is included in Appendix X1 to provide the required moist air.

5.3.13 Oven, optional, to dry glassware at elevated temperature.

5.3.14 Forceps, stainless steel.

5.3.15 Thermocouple, 70 cm (27.6 in.) sheathed.

5.3.16 Brush, short-bristled, stiff (typewriter-cleaning brush or equivalent).

6. Reagents and Materials
6.1 Purity of Reagents - Reagent grade chemicals shall be used in all tests. Unless otherwise indicated, it is intended that all reagents conform to the specifications of the Committee on Analytical Reagents of the American Chemical Society where such specifications are available. Other grades may be used provided it is first ascertained that the reagent is of sufficiently high purity to permit its use without lessening the accuracy of the determination.

6.2 Purity of Water - Unless otherwise indicated, references to water shall be understood to mean reagent water as defined by Specification D1193. Referee situations require Type II distilled water defined by Specification D1193.

6.3 Metal Specimens:
6.3.1 Washer-Shaped Metal Specimens, 6.35-mm (1/4-in.) inside diameter by 19.05-mm (3/4-in.) outside diameter by 0.81 mm (0.032 in.) thick in the following metals:
R56080: Titanium 8 % Mn
M11311: Magnesium AZ31B
T11350: Steel M50
G10100: Steel grade 1010
C65900: Silicon-iron-bronze
P07015: Silver 99.95
A92024: Aluminum Alloy 2024 T-3 or T-4

6.3.2 Square-Shaped Metal Specimens (as shown in Fig. 6), 0.81-mm (0.032-in.) by 25.4-mm (1-in.) square in the following metals:
C11000: Copper (ETP)
G10100: Steel Grade 1010
A92024: Aluminum Alloy 2024 T-3 or T-4
M11311: Magnesium AZ31B
L01900: Cadmium Anod

6.4 Abrasive Paper, silicon carbide, various grades, including 240 and 400-grit. Many papers, including "wet or dry", "waterproof", or iron-containing abrasives, such as natural emery are not satisfactory.

6.4.1 Silicon-Carbide Grains, 150 mesh.

6.5 Cotton, absorbent.

6.6 n-Heptane. (Warning - Flammable. Harmful if inhaled.)

6.7 Acetone. (Warning - Extremely flammable. Vapors may cause flash-fire.)

6.8 Nitric Acid, concentrated. (Warning - Poison. Corrosive. Strong oxidizer.)

6.9 Degreasing Solvents: n-Heptane or toluene.

6.10 Carbon Remover for Glassware (Warning - Causes severe burns.) - Mix 35 mL of saturated sodium dichromate (aqueous) solution and 1000 mL of concentrated sulfuric acid. (Warning - Corrosive.)

6.11 Glassware Cleaning Solution (Warning - Causes severe burns.) - Mix 35 mL of MICRO in water or 35 mL of NOCHROMIX and 1000 mL of concentrated sulfuric acid.

6.12 Metal Cleaning Solution - Mix equal parts of 15 g NaOH per litre of water and 15 g of Na3PO4 per litre of water. (Warning - Corrosive.)

7. Hazards
7.1 As this test method investigates the corrosive effect of oil on metal in an artificial environment, precautions must be taken to prevent premature oxidation of metal specimens by stray chemicals during test preparations. The cleaned specimens shall be touched only by surfaces known to be free of interfering contaminants. Do not touch cleaned specimen(s) with hands. Maintain clean glassware (see Appendix X2) in a dust-free cabinet; rinse again and dry if clean glass has been stored unused for more than a week.

7.2 Heating Bath, n-heptane, toluene, acetone, carbon remover, nitric and sulfuric acids, and sodium hydroxide all require caution in handling as detailed in 5.3.1 and 6.6-6.12.