April 15, 1931
INDUSTRIAL A N D ENGINEERING CHEMISTRY
about the omosite effect. I n this service. unless onlv verv small differences of pressure of the liquid'supply are" to ge smoothed out, the control is no better than that of a Marriott bottle.
143
Literature Cited
A.
(1) Hickman, J . Oplical sot. A m , , 18, 305 (1929). (2) Othmer. IND. ENG. CHEM., a2. 322 (3) Othmer; Ibid., Anal. Ed., 1, 97 (lQ29).
Comparative Efficiencies of Gas-Washing Bottles' F. H. Rhodes and D. R. Rakestraw CORNELLUNIVERSITY, ITAACA. N. Y. 2
HE investigation described in this article was under-
the system. If no precipitate appeared in the U-tube within
taken for the purpose of obtaining information as to the comparative efficiencies of some of the typesof gas-washing bottles commonly used in chemical laboratories. Each test was made by passing a known mixture of air and carbon dioxide through a solution of sodium hydroxide contained in the bottle, and determining the percentage of carbon dioxide in the exit gas at various rates of flow. The apparatus used is shown in Figure 1. Carbon dioxide from a cylinder of the liquefied gas was passed through a capillary orifice meter, A , and mixed with air which was admitted through a second orifice meter, B. By maintaining a constant reading on each of the two manometers, A1 and B1, mixed gas of constant composition was obtained.
3 minutes, the rate of flow of the gas was increased slightly
T
A
and an observation was taken as before. Repeated tests were made at increasing rates of flow until a point was found a t which the carbon dioxide in the ihlet air was no longer completely absorbed by the alkaline solution in the wash bottle. After the point a t which complete absorption can be obtained was determined, the stopcocks in the dischargeTline were set so that all of the gas passed directly to the orifice meter, E, and tests were made a t higher rates of flow. At each rate, observations were taken to determine the rate of flow of the exit gas, the percentage of carbon dioxide in the exit gas, and the drop in pressure through the washing bottle. The gas-washing bottles tested were as follows: HEIGHT OF
BOTTLE
TYPE
SOLN.DURING NOFLVAL OPERATION Cm.
1 2 3 4 5 6 Figure 1-Diagram
of Apparatus Used
7 8
Constant pressure on the discharge side of the orifice meters was maintained by keeping the rate of flow of gas high enough to maintain constant flow of gas through the water-sealed discharge tube, C. The mixed gas was passed through a solution of sodium hydroxide in the bottle to be tested, D,and then through a calibrated orifice meter, E , which measured the rate of flow of the exit gas. A manometer, F,was connected across the line so as to measure the drop in pressure through the bottle. The rate of flow of gas through the train was regulated by the stopcock G. Samples of the inlet gas were Collected a t H ; the outlet gas was sampled at I . A by-pass was placed in the exit-gas line so that the washed gas could be passed through a U-tube, J,containing a solution of barium hydroxide. Samples of gas for analysis were collected in a Hempel buret over mercury and were analyzed by absorbing the carbon dioxide in a solution of caustic soda contained in a Hempel pipet. The bottle to be tested was filled to the normal working height with a solution of sodium hydroxide (32.7 grams per liter) and was inserted in the train. Air was passed through &hesystem to sweep out any carbon dioxide that might be present. A clear solution of barium hydroxide was placed in the U-tube, J, and stopcocks JI,Jz,K1,and KZwere set so that all of the exit gas passed through this solution. If no precipitate appeared within 3 minutes, the current of air was discontinued and a mixture of air with a known amount of carbon dioxide was passed very slowly through 1 Received
December 10, 1930.
Muencke Friedrichs spiral Habermann Habermann Schott and Gen. (Jena), with sintered-glass distributing plate, inlet tube at center of plate Schott and Gen., with sintered-glass distributing plate, inlet tube at side of plate, pattern No. 83 Schott and Gen., sintered-glass distributing plate, pattern No. 101 Muencke with space between inlet tube and wall of bottle filled with glass beads approx. 3 mm. in diameter
"0
2
4 6 8 IO 12 RATE OF FLOW- CC./SEC.
Figure 2-Determination
10.5 11 11 14.5
12 12 15.5
10.6
I4
with 13.4 Per Cent COz in Inlet Gas
Two series of determinations were made, one with an inlet gas containing 13.4 per cent of carbon dioxide, and the other with a n inlet gas containing 5.1 per cent of carbon dioxide. The results are shown in Figures 2 and 3. The tests made with the inlet gas of high concentration show that the Friedrichs spiral gas-washing bottle was the most efficient of all the forms tested by us. No carbon dioxide could be detected in the exit gas until the rate of flow exceeded 4.3 cc. per second, and even at higher rates the percentage of unabsorbed carbon dioxide in the outlet gas was
0
.
VOl. 3, No. 2
ANALYTICAL EDITION
144
f 6 8 lo I2 RATE OF FLOM- CC./SEC.
2
Figure 3-Determination
I4
with 5.1 Per Cent COPin Inlet Gas
low. Bottle 7 (Schott and Gen. pattern 101) gave results only slightly inferior to those obtained with the bottle of the spiral type. The poorest results were obtained with the bottles of the Muencke and the Habermann types, the Muencke bottle being only slightly more: efficient than the Habermann bottles. Somewhat similar results were obtained in the experiments made with the inlet gas that contained only 5.1 per cent of carbon dioxide. Decreasing the concentration of the absorbable component in the original mixture has comparatively little effect in increasing the maximum rate at which the gas can be passed through any particular bottle without allowing a detectable amount of carbon dioxide to pass through unabsorbed. A comparison of curves 1 and 8 in Figure 3 shows that the efficiency of the commonly used Muencke bottle can be increased to a considerable extent by filling the space between the inlet tube and the wall of the bottle with glass beads. From the results shown in Figure 4 it is apparent that
0
I 8
4
I
I
I f2
/6
RATE OF fL.OW-CC/SEC Figure 4-Com
arison of Pressure Drop in $arious Bottles
the drop in pressure is considerably greater in those bottles that are provided with a distributing plate of sintered glass. This is to be expected, since in bottles of this type pressure is required not only to overcome the static head of the Iiquid, but also to force the gas through the small pores of the distributing plate.
Alignment Chart for Estimating Viscosity-Gravity Constant of Petroleum Lubricating Oils' W. F. Houghton and J. A. Robb THE ATLANTIC REFININQCOMPANY, PHILADELPHIA, PA.
T H E viscosity-gravity constant as developed by Hill and Coats ( I ) has been found to be a great aid in defining and classifying lubricating oils. It affords a convenient means for following the progress of various refining processes such as acid treatment and solvent extraction. From tests on the heavier fractions of crude oils, it gives an excellent clue to the properties of all the fractions. Table I gives the viscosity-gravity constants of lubricating cuts from various crude oils and shows the value of this index as a means of classification and identification. Constants of Lubricating Cuts from Table I-Viscosity-Gravity Various Crude Oils Reagan County Tex. 0.839 0.918 Sour Lake, Tex. 0,829 Salt Creek, Wy& 0.894 Heavy Mexican Burbank. Okla. 0.828 0.885 Sunset Calif. 0.827 Ranger, +ex. Spindl&op, Tex. 0.876 0.804 Eureka, Pa. Light Mexican 0.860 0.800 Buckeye, Ohio. Van Zandt County, Tex. 0.852 0.800 Milltown, Pa. 0.844 Seminole, Okla. ~~~
The viscosity-gravity constant is based on a relation between Saybolt viscosity and specific gravity as follows:
G
+ 1.0752 - A
log(V-338) -_ viscosity-gravity constant specific gravity at 60' F. (1.5.6" C.) V = Savbolt viscosity at 100' F. (37.8' C.)
where A G 1
=A
= =
Received November 7 , 1930.
When the viscosity is measured at 210' F. (98.9' C.), the following equation is used: G = 0.24 0.7558 0.022 log (V' - 35.5) where V' = Saybolt viscosity at 210' F. (98.9' G.) These equations are rather cumbersome and make the calculation of the constant so tedious as to detract from its general usefulness. To eliminate this factor, an alignment chart has been constructed which permits the rapid estimation of the constant from the viscosity and gravity data. I n this chart the left side is to be used for viscosities a t 210" F. (98.9' C.) and the right side for viscosities a t 100' F. (37.8' C,). I n using the chart for the evaluation of A , connect by means of a straight edge the proper mark on the viscosity scale with the corresponding value on the gravity scale. Then the value of A is given by the intersection of this line with the viscosity-gravity constant scale. For example, a Winkler distillate has a viscosity of 92 Saybolt seconds a t 210' F. (98.9' C.) and a gravity of 18.6' A. P. I. The constant is found to be 0.880. Another distillate has a viscosity of 350 Saybolt seconds a t 100" F. (37.8" C.) and a gravity of 28.4' A. P. I. The constant in this case is 0.822. This distillate falls in the class of highly paraffinic mixed-base lubricating crudes such as Williamson County, Texas.
+
+
Literature Cited (1) Hill and Coats, IND.ENG.CHEM., 20, 641 (1928).
