ASTM D473 test method for sediment in crude oils and fuel oils
ASTM D473 standard test method for sediment in crude oils and fuel oils by the extraction method
5. Apparatus
5.1 Usual laboratory apparatus and glassware, together with the following are required for this test method.
5.1.1 Extraction Apparatus - Use the apparatus illustrated in Figs. 1 and 2 and consisting of the elements described in 5.1.1.1-5.1.1.3.
5.1.1.1 Extraction Flask - Use a wide-neck (Erlenmeyer) flask of 1-L capacity, with a minimum external neck diameter of 50 mm, for the procedure.
5.1.1.2 Condenser - A condenser in the form of a metal coil approximately 25 mm in diameter and 50 mm in length attached to, and with the ends projecting through, a lid of sufficient diameter to cover the neck of the flask as shown in Fig. 1. The coil shall be made from stainless steel, tin, tin-plated copper, or tin-plated brass tubing having an outside diameter of 5 to 8 mm and a wall thickness of 1.5 mm. If constructed of tin-plated copper or brass, the tin coating shall have a minimum thickness of 0.075 mm. The exposed surface of the coil for cooling purposes is about 115 cm2.
NOTE 2 - The use of a water flowmeter/controller unit that monitors water flow to the condenser that shuts off the heat source when the flow rate drops below a pre-set limit has been found suitable to prevent vaporized toluene from igniting. The use of such a device is recommended.
5.1.1.3 Extraction Thimble - The extraction thimble shall be of a refractory porous material, pore size 20.0 to 30.0 µm (as certified by the manufacturer), 25 mm in diameter by 70 mm in height, weighing not less than 15 g and not more than 17 g. Suspend the thimble from the condenser coil by means of a basket so that it hangs approximately midway between the surface of the extracting solvent and the bottom of the condenser coil.
5.1.1.4 Thimble Basket - The thimble basket shall be corrosion-resistant and shall be made of platinum, stainless steel, nickel-chromium alloy, or similar material. Fig. 2 shows the design and dimensions of two typical baskets that have been used successfully in the industry.
5.1.1.5 Water Cup - Use a water cup when testing a sample determined to have a water content greater than 10 % volume (see Fig. 1, Apparatus B). The cup shall be made of glass, conical in shape, approximately 20 mm in diameter and 25 mm deep, and have a capacity of approximately 3 mL. A glass hook fused on the rim at one side is so shaped that when hung on the condenser the cup hangs with its rim reasonably level. In this procedure, suspend the thimble basket as shown in Fig. 1, Apparatus A by means of the corrosion-resistant wire looped over the bottom of the condenser coil and attached to the basket supports, or as in Fig. 1, Apparatus B, where the wire supports of the basket are attached to hooks soldered to the underside of the condenser lid.
5.1.1.6 Source of Heat - Use a source of heat, preferably a hot plate operated under a ventilated hood, suitable for vaporizing toluene (Warning - Flammable.)
5.2 Analytical Balance - Use an analytical balance, with an accuracy of 0.1 mg. Verify the balance, at least annually, against weights traceable to a national standards body such as the National Institute of Standards and Technology (NIST).
5.3 Non-aerating Mixer - Use a non-aerating mixer, meeting the verification of mixing efficiency requirements specified in Practice D5854 (API Chapter 8.3). Either insertion mixers or circulating mixers or circulating external mixers are acceptable provided they meet the criteria in Practice D5854 (API Chapter 8.3).
5.4 Oven - Use an oven capable of maintaining a temperature of 115 to 120°C (240 to 250°F).
5.5 Cooling Vessel - Use a desiccator without desiccant as a cooling vessel.
5.6 Temperature Measuring Device - Such as a thermometer, capable of measuring the temperature of the sample to the nearest 1°C (2°F).
6. Solvent
6.1 Toluene - Reagent grade conforming to the specifications of the Committee on Analytical Reagents of the American Chemical Society (ACS) or to Grade 2 of ISO 5272. (Warning - Flammable. Keep away from heat, sparks and open flame. Vapor harmful. Toluene is toxic. Particular care shall be taken to avoid breathing the vapors and to protect the eyes. Keep the container closed. Use with adequate ventilation. Avoid prolonged or repeated contact with the skin.)
6.1.1 The typical characteristics for the ACS reagent are shown in Table 1.
7. Sampling
7.1 Sampling shall include all steps required to obtain an aliquot of the contents of any pipe, tank, or other system and to place the sample into the laboratory test container.
7.2 Only use representative samples obtained as specified in Practices D4057 (API Chapter 8.1) and D4177 (API Chapter 8.2) for this test method.
7.3 Draw test portions from the laboratory samples immediately after thorough mixing. Heat viscous samples to a temperature which renders the sample liquid, and homogenize using a mixer as described in 5.3, as necessary. The difficulties of obtaining a representative test portion for this determination are usually great, hence the need for great attention to the mixing and aliquoting steps.
7.4 As specified in Practice D5854 (API Chapter 8.3), record the temperature of the sample before mixing. Mix the laboratory sample in its original container, using the mixing time, mixing power (speed), and position relative to the bottom of the container appropriate to the crude petroleum or fuel oil being analyzed, and as established by the verification of mixing efficiency. To avoid the loss of light ends from crude oil or other samples containing volatile material, operate the mixer through a gland in the closure of the sample container. Take the test portion for analysis immediately after mixing. Record the temperature of the sample immediately after mixing. If the rise in temperature during mixing exceeds 10°C (20°F), cool the sample, and repeat the mixing at a lower energy input. A rise in temperature greater than 10°C (20°F) may result in a decrease in viscosity that is sufficient for the sediment to settle.
