ASTM D4898 Test Method for Insoluble Contamination of Hydraulic Fluids by Gravimetric Analysis
5. Apparatus
5.1 Microbalance, accurate to 0.005 mg, and the zero shall not drift more than 0.005 mg during the test period. The rated accuracy shall be obtainable by personnel actually making the weighings, under actual conditions of use and shall be verified in accordance with Practice E319.
5.2 Membrane Filter Support, fritted glass, sintered metal, or stainless steel screen, to support 25 mm or 47 mm to 51 mm membrane filters. The support shall be designed to enable attachment of a vacuum flask.
5.3 Filtration Funnel, glass or stainless steel, minimum capacity 15 mL, designed to enable attachment to the membrane filter support by means of a suitable clamping device. The filter funnel is calibrated to indicate volume.
5.4 Vacuum Flask, with rubber stopper.
5.5 Filtered Liquid Dispensers (2) - Washing bottles or other dispensers capable of delivering liquid through a 0.45 µm in-line membrane filter.
5.6 Air Ionizer, alpha emitter, 18.5 MBq, of polonium-210, with a useful life of 1.5 years to a final value of 1.1 MBq.
5.7 Membrane Filters (2), 25 mm or 47 mm to 51 mm in diameter, with pore diameter as required.
5.8 Microscope, capable of 35x magnification.
5.9 Vacuum Source, capable of pulling 550 mm Hg. An electrically driven vacuum pump must be explosion-proof.
5.10 Drying Oven, capable of maintaining a temperature of 80 °C.
5.11 Sample Bottles, with contamination-proof caps. Aluminum-foil wrapped stoppers or polyethylene liners between cap and bottle have proved satisfactory.
5.12 Graduated Cylinder, 100 mL (May be replaced by volume-calibrated filter funnel.)
5.13 Petri Dishes, covered glass, 150 mm in diameter.
5.14 Forceps, with unserrated tips.
5.15 Calibration Weights, for microbalance, 10 mg and 20 mg, accurate to 0.005 mg and made from nonmagnetic material conforming to Type 310 in Specification A555/A555M. The accuracy is traceable to the National Bureau of Standards as discussed in their Technical Note 288.
6. Reagents
6.1 Commercial Hexane, conforming to Specifications D1836. (Warning - Flammable. Harmful if inhaled. Skin irritant on repeated contact. Eye irritant. Aspiration hazard.)
6.2 Detergent, free-rinsing. Material conforming to Specification D2021.
6.3 Isopropyl Alcohol, acetone-free. (Warning - Flammable. Harmful if inhaled. Skin irritant on repeated contact. Eye irritant. Aspiration hazard.)
6.4 Refrigerant-113 (trichlorotrifluoroethane) conforming to U.S. Military Specification MIL-C-81302C. (Warning - Environmentally hazardous substance. Harmful if inhaled. Skin irritant on repeated contact. Eye irritant. Aspiration hazard. Acute and chronic aquatic hazard.)
7. Sample
7.1 A 100 mL +/- 1 mL fluid sample should be used for this method. Larger or smaller samples may be used, however, to meet problems of unusually high or low contamination levels.
NOTE 1 - Methods for obtaining the fluid samples are not specified in this method. These methods should be established by the individual agencies or laboratories in accordance with their requirements. However, extreme care should be taken to ensure that the samples are representative and free of external contamination.
7.2 The following ASTM sampling test methods should be used when applicable: Practices F302 and F303.
8. Preparation of Apparatus
8.1 The filtration funnel, petri dishes, graduated cylinders, and sample bottles shall be cleaned before each use by the following method:
8.1.1 Thoroughly wash in a solution of detergent and hot water.
8.1.2 Rinse with hot tap water and finally with distilled or deionized water.
8.1.3 Rinse twice with filtered isopropyl alcohol (delivered through a filtered liquid dispenser).
8.1.4 Rinse twice with filtered commercial hexane (delivered through filtered liquid dispenser).
8.1.5 Leave approximately 1 mL of commercial hexane in the bottom of each sample bottle. Replace sample bottle cap. (Warning - Flammable. Harmful if inhaled. Skin irritant on repeated contact. Eye irritant. Aspiration hazard.)
