ASTM D1665 Test Method for Engler Specific Viscosity of Tar Products
6. Apparatus
6.1 Engler Viscosimeter as shown in Fig. 1, consisting of the following:
6.1.1 Cup - This is a gold-plated cylindrical brass vessel of 106.0 ± 1.0 mm, A, inside diameter, closed at the top by a double walled lid. To the rounded bottom is attached a metal-encased tapered platinum efflux tube 20.0 ± 0.1 mm, H, long with an inside diameter of 2.90 ± 0.02 mm, E, at the top and 2.80 ± 0.02 mm, F, at the bottom. The efflux tube shall project through and extend 3.0 ± 0.2 mm, G, below a jacket that surrounds the cup and shall have a bottom outside diameter, including its surrounding metal, of 4.5 ± 0.2 mm, I. Three metal measuring points, spaced equidistantly around the circumference of the cup, are fastened to the sides and extend inwardly approximately 7 mm, then turn up at a right angle and end in sharp points which are located 52.0 ± 0.5 mm, D, vertically above the lower end of the efflux tube and 25.0 ± 1.0 mm, C, above the lowest portion of the cylindrical sidewall of the cup. They serve both for indicating when the instrument is level and for measuring the charge of material, which is approximately 250 mL.
6.1.2 Jacket - The cup is surrounded by a jacket which holds water or other suitable liquid serving as a constant temperature bath. In the type illustrated, the jacket is provided with a thermometer clamp and stirring device. A tripod supports the apparatus and also carries a ring burner by means of which the bath is heated. Adjustable legs on the tripod serve to level the instrument. Other arrangements of outer baths, supports, and stirring devices are acceptable, especially when it is desired to use more than one standardized cup in a single bath.
6.1.3 Stopper - The efflux tube in the cup is closed or opened by the insertion or withdrawal of a tapered hardwood stopper which, to leave the tube open, can be suspended by its brass pin from the hook on the cover. The stopper shall be a smooth, round, wooden rod 180 mm long and 8 mm in diameter, with a brass wire pin 20 mm and 1.83 mm in diameter long inserted diametrically through the rod at a point 50 mm from the lower end, and tapered uniformly below this pin to end in a circular plane 1.6 to 2.0 mm in diameter. Above the pin the rod shall be planed or grooved on four sides to a depth of 1 mm to prevent any possible restriction of air flow.
6.2 Receivers - Two types are required as follows:
6.2.1 Testing Flask - 50 mL graduate calibrated at 20°C (see Fig. 2).
6.2.2 Calibration Flask - For standardization purposes there shall be available a Kohlrausch flask, Fig. 3, with top enlarged above the graduation mark and calibrated to contain 200 ± 0.1 mL at 20°C.
6.3 Thermometers - ASTM Engler Viscosity Thermometers 23C, 24C, and 25C as required, and conforming to the requirements for these thermometers as specified in Specification E1.
6.4 Timer - Stop watch or other timing device graduated in divisions of 0.2 s or less, and accurate to within 0.1 % when tested over a 60-min period.
6.5 Strainer - 300 mm ASTM sieve conforming to Specification E11.
7. Sampling
7.1 Samples from shipments or production vessels shall be taken in accordance with Practice D140 and shall be free of foreign substances. Thoroughly heat and stir the sample before removing a representative portion for the determination.
