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whose capacity to a mark on its neck is 60 (±0.15) c.c. The lower end of the outlet tube is enclosed by a larger tube, which when stoppered by a cork, N, acts as a closed air chamber and prevents the flow of oil through the outlet tube until the cork is removed and the test started. A looped string is attached to the lower end of the cork as an aid to its rapid removal. The bath is provided with two stirring paddles, K, and operated by two turntable handles F. The temperatures in the standard oil tube and in the bath are shown by thermometers, A and B. The bath may be heated by a gas ring burner P, steam U-tube H, or electric heater, C. The standard oil tube is cleaned by means of a tube cleaning plunger V, and all oil entering the standard oil tube shall be strained through a 30-mesh brass wire strainer Q. A stop watch is used for taking the time of flow of the oil and a pipette, fitted with a rubber suction bulb, is used for draining the overflow cup of the standard oil tube.
(b) The standard oil tube should be standardized by the United States Bureau of Standards, Washington, and shall conform to the following dimensions:
at 100° F. (37°.8 C.),
3. Viscosity shall be determined 130° F. (54°.4 C.), or 210° F. (98°.9 C.). The bath shall be held. constant within 0°.25 F. (0.14° C.) at such a temperature as will maintain the desired temperature in the standard oil tube. For viscosity determinations at 100 and 130° F., oil or water may be used as the bath liquid. For viscosity determinations at 210° F.. oil shall be used as the bath liquid. The oil for the bath liquid. should be a pale engine oil of at least 350° F. flash point (open cup). Viscosity determinations shall be made in a room free from draughts, and from rapid changes in temperature. All oil introduced into the standard oil tube, either for cleaning or for test, shall first be passed through the strainer. To make the test,
heat the oil to the necessary temperature and clean out the standard oil tube with the plunger, using some of the oil to be tested. Place the cork stopper into the lower end of the air chamber at the bottom of the standard oil tube. The stopper should be sufficiently inserted to prevent the escape of air, but should not touch the small outlet tube of the standard oil tube. Heat the oil to be tested, outside the viscosimeter, to slightly below the temperature at which the viscosity is to be determined and pour it into the standard oil tube until it ceases to overflow into the overflow cup. By means of the oil tube thermometer keep the oil in the standard oil tube well stirred and also stir well the oil in the bath. It is extremely important that the temperature of the oil in the oil. bath be maintained constant during the entire time consumed in making the test. When the temperature of the oil in the bath and in the standard oil tube are constant and the oil in the standard oil tube is at the desired temperature, withdraw the oil tube thermometer; quickly remove the surplus oil from the overflow cup by means of a pipette so that the level of the oil in the overflow cup is below the level of the oil in the tube proper; place the 60 c.c. flask in position so that the oil from the outlet tube will flow into the flask without making bubbles; snap the cork from its position, and at the same instant start the stop watch. Stir the liquid on the bath during the run and carefully maintain it at the previously determined proper temperature. Stop the watch when the bottom of the meniscus of the oil reaches the mark on the neck of the receiving flask. The time in seconds for the 60 c.c. of oil is the Saybolt viscosity of the oil at the temperature at which the test was made.
Other viscosimeters in use are the Engler, Tagliabue, Scott, Redwood, Penn. Ry. pipet, McMichael, Lamansky-Nobel, Ostwald, Martens, Stormer, Ubbelohde, Lepenau, Kuenkler, Albrecht, Arvine, Barbey, Cockrell, Doolittle, Gibbs, Mason, Napier, Nasmyth, Phillips, Reischauer, Magruder. The Engler viscosimeter (See fig. 5) is used most extensively in Germany and its dimensions are as follows:
Inside diameter of the inside vessel for oil....106 mm.
Length of the oil jet.....
Inside diameter of the oil jet upper end...... 2.9 mm.
Inside diameter of the oil jet lower end....... 2.8 mm.
The quotient of the time of outflow of 200 c.c. of oil divided by the time of outflow of 200 c.c. of water is taken as a measure of the viscosity or is the so-called Engler degree. The Redwood viscosimeter is used extensively in England.
Table 6.-EQUIVALENT READINGS FOR THE SAYBOLT, REDWOOD AND ENGLER VISCOMETERS.
Table 6 gives equivalents of Saybolt times, Redwood times, and Engler numbers. Intermediate values can be obtained by interpolation. Fig. 6 is a chart for the quick determination of these equivalents.
a. Compiled by Carl D. Miller, Ph.D., Associate Editor of Oil News.
Knowledge of the viscosity of fuel oil is valuable for determining the ease with which the oil can be pumped through pipe lines with or without heat. Although the viscosity of fuel oil increases with the density, tests have shown that oils of the same specific gravity from different localities often differ quite widely in viscosity.
Fuel oil, as regards viscosity, may be divided into two general classes, namely: Class 1. Asphaltic base crudes, residuums, or
Given: Saybolt time' = 100
To find: Redwood time and Engler number. Saybolt time 100 is found in the center chart. Read Straight across and find 85 on the scale of Redwood times at the right, and 28 on the scale of Engler numbers.
FIG. 6.-Chart for quick determination of Saybolt equivalents.
other oils which require heating facilities to reduce the viscosity in order that the oil may be handled by the storage and burning. equipment. Class 2. Oils of a sufficiently low viscosity to make heating equipment unnecessary. In general, an oil in Class 1 should not have a viscosity above 2,000° Engler at 60° F. Oils of a higher viscosity than this can be used at plants provided with special equipment. It is imperative that oils of this class be heated