ASTM D6986 Standard Test Method for Free Water, Particulate and Other Contamination in Aviation Fuels (Visual Inspection Procedures)
6. Apparatus
6.1 Cylindrical Clear Container, such as:
6.1.1 Clear Container, with lid, capable of holding 750 mL (nominal 1 U.S. qt) of fuel and having a diameter of 100 mm +/- 10 mm (4 in. +/- 0.4 in.). There should be no gasket in the lid.
6.1.2 Closed Circuit Sampler, holding about 4 L (1 gal U.S.) of fuel and being permanently mounted to receive fuel from a fuel line or a storage tank and having inlet and outlet valves to control filling and emptying of the container. The sampler base is normally conical and incorporates the fuel inlet and outlet. The fill port is designed to cause the fuel to swirl around the sides of the clear glass tube. The circuit sampler may also contain hydrometer and chemical water detection ports.
6.2 Appearance Card and Photographs:
6.2.1 Paper Card (Bar Chart), laminated in clear plastic having five parallel lines of different widths (see ASTM adjunct ADJD417601).
6.2.2 Appearance Photographs, a series of standard photographs of the bar chart through a series of samples of different haze levels, numbered from one through six. Photograph No. 1 is the clearest, while No. 6 represents the densest haze (see ASTM adjunct ADJD417602). A fuel sample rated clear and bright will have a rating of "one".
6.2.2.1 The differences between these haze levels are arbitrary and are not intended to represent equivalent increases in suspended water content or particulates. It is essential, therefore, that only the proper approved bar charts and photographs be used.
6.3 Opaque Sample Containers:
6.3.1 White Bucket, a circular bucket with straight but non-parallel sides and a flat bottom and a minimum capacity of 7.5 L (2.0 U.S. gal) and approximately 20 cm (8 in.) high, either coated with white porcelain enamel or made of stainless steel. Porcelain coatings must be free of dark spots, chips, or other surface damage, most particularly on the bottom of the bucket. Stainless steel buckets shall be made of a rust-resistant steel and have a polished internal surface. The white porcelain bucket should be used for the optimum detection of unusual coloration.
NOTE 1 - A quantitative description of acceptable white color is in preparation.
NOTE 2 - Buckets made of white, hard plastic have been found to stain a yellow color over time, which can make it difficult to observe a haze or color changes. The use of plastic containers is also discouraged unless provision is made for bonding such containers to the filling line.
6.4 Color and Particle Assessment Rating Guide:
6.4.1 This guide contains both a series of photographs of particulates of differing concentrations, each having a different letter rating, and a series of color photographs for rating filter membranes obtained by Test Methods D2276. For this test method, only the particle rating scale is used. The particle rating scale does not bear a direct relationship to the mass of particulates but is simply a way of communicating the amount of visible particulates in the sample.
7. Sampling
7.1 Sampling shall be consistent with the procedures in Practice D4057.
7.2 Draw the sample for a field test directly into the test container using the following procedure:
7.2.1 Ensure that the sampling valve is free of loose solid contaminants. If rust or other loose encrustation is present, remove with a cloth; then flush the sampling valve prior to taking the actual sample.
7.2.2 Ensure the displacement the fuel volume in the piping between the sample tap and the storage tank This displacement volume should be discarded as it may not be representative of the fuel to be tested.
7.2.2.1 All fluid obtained from a filter sump should be kept as the sample.
7.2.3 Rinse a clean test container thoroughly with the fuel being sampled. (Warning - Flammable, keep away from heat, sparks, and open flames.)
7.2.4 Draw the sample continuously, opening the valve completely to obtain a full flush. Do not open or close taps or valves during sample draw as this action can affect sample quality.
7.3 If the test is to be conducted on fuel taken in a separate container for laboratory testing, the container should be shaken vigorously before decanting the fuel into the viewing equipment. Sample transfer should be rapid enough to avoid changes in sample temperature.
