1826
INDUSTRIAL AND ENGINEERING CHEMISTRY
rz = 0.1,r y = 0.002, and r; = 0.02. The nomograph constructed on these values is shown in Figure 7. METHODSOF READIXG.Reading three-dimensional nomographs is not so simple as reading planar nomographs, since constructing a plane through three given points presents more of a problem than drawing a straight line through two points. Nevertheless, several feasible methods present themselves, one of which is the method suggested b y d’Ocagne ( 5 ) . The nomograph is constructed in the form of a device having a peephole on one of the scales, through xhich the user sights t o a line drawn between given points on two other scales. The point a t which t h a t line appears t o intersect the fourth scale is the desired solution. The author prefers to use two or three contacting straight edges, such as rulers or stretched wires. These are much simpler to construct and mag be applied to any type of three-dimensional nomograph. In most applications, computation is the prime purpose of nomographs. However, they are also useful for the graphical
Vol. 43. No. 8
representation of functionally relt~ted parameters, serving as aids to visualization of involved relationships. For this latter purpose the method of reading need not be precise. Hence, the three-dimensional nomograph is peculiarlg well adapted to that purpose and presents a means of demonstrating relationships among four related parameters vihich is not easily achiwed with three-dimensional graphs. LITERATURE CITED
(1) Burrows, W. H., ISD. ENG.CHEX.,38, 472 (1946). (2) Ibid.,43, 1193 (1961). (3) Burrows, W.H., J . Eng. Education, 36, 361 (1946). (4)Castles, W., Jr., J . Aeronaut. Sci., 12, 477 (1945). (5) d’Ocagne, M., “Trait6 de Nomographie,” 1st ed., p. 348, Paris, Gauthier-Villars, 1921. (6) Perry, John H., “Chemical Engineers’ Handbook,” 2nd ed., p. 1383, Xew York, McGram-Hill Book Go., 1941. (7) I b i d . , p. 1396. RECEIVED March 9, 1951.
High Pressure Metal-to-Glass Fitting P. C. DAVIS, T. L. GORE, AND FRED 16URL4TA University of Kansas, Lawrence, Kan. During a study of high pressure vapor-liquid equilibria of hydrocarbon mixtures, it became necessary to make a pressure-tight closure between a glass capillary tubing and high pressure steel tubing which was capable of withstanding pressures up to 2000 pounds per square inch under considerable vibration. A satisfactory closure was developed, utilizing end thrust of glass tubing against a rubber O-ring. This closure can be assembled by hand to seal against pressures in excess of 3000 pounds per square inch under considerable vibration and is easily constructed and assembled. Modifications of the closure described would provide effective high pressure seals against a variety of brittle materials which can be formed by heating and/or grinding. These closures could be quicldy dismantled and reassembled and would be more resistant to vibration than soldered or welded fittings.
I
N CONNECTION with a study of vapor-liquid equilibria of
hydrocarbon mixtures, i t became necessary to make a pressure-tight closure, capable of containing pressures up to 2000 pounds per square inch, between a glass capillary tubing and high pressure steel tubing. In order to keep to a minimum the amount of the fluid contained within the closure, it was necessary to minimize the volume within the fitting itself. It was first attempted t o use the usual closure in which the glass is plated with copper over platinum, and the plated portion is soldered into a metal fitting t o which the high pressure steel tubing can be connected. The seal thus obtained was pressure-tight but proved t o be too fragile to resist vibration. This weakness
5/,“
was attributed to localized stresses set up in the glass during the soldering which could not be relieved by annealing because of the low melting point of solder. Also considerable skill is required in the plating technique t o effect a pressure-tight seal. For these reasons other types of closures were investigated. Onnes and Braak ( 1 ) used a closure in which glass tubing was connected to a metal socket with shellac, but this type of seal was unsuitable. Figure 1 illustrates a closure which eliminates the soldered joint and which has proved satisfactory. It has successfully contained pressures up to 3000 pounds per square inch and has withstood considerable vibration. The pressure a t which the seal failed could not be determined because of the lower bursting pressure of the glass capillary. The seal is effected by conipressing a rubber O-ring gasket, which is supported by a groove in the metal male fitting, against the ground end of the glass capillary. The glass tubing is upset t o form a shoulder against which a metal support ring can bear and this metal ring is held in the female fitting by means of a set screw. The female fitting is cut away on
I
C Set Serow
6/64m
x 3 ’ o d by 0.110”ld.
A?
‘/16” eraphite A9beltoB washer
0.10‘ad by ‘/64” id. Drive Fit
Figure 1. Detail of High Pressure Metal-to-Glass Connection Scale 1 inch
=
1 inch
August 1951
I N D U S T R I A L AN.D E N G I N E E R I N G C H E M I S T R Y
1821
one side t o allow visual inspection of the clearance between the male fitting and the glass tube. Figure 2 shows the disassembled and assembled views of a typical fitting. The dimensions and details of construction may be varied considerably from those shown in Figure 1 depending on the requirements. For example, it might be desirable t o use a split supporting ring rather than the solid one shown, should i t be inconvenient to put this ring in place on the glass before forming the upset shoulder. Other methods can be used to compress the O-ring gasket against the end of the glass. Although one set screw on the support ring proved t o be amply strong, three set screws would provide added strength. Since it was desired to minimize the amount of free volume within t h e fitting itself, the fitting was not constructed according to the standard Army-Navy (A/N? specifications. If the amount'of the free volume within the closure is not critical, the closure can be constructed according t o the standard specifications. The cut-away portion on one side of the female fitting is not necessary unless visual inspection of the clearance is desired. This closure has been used only at room temperature, but the use of O-rings of special materials such as silicone rubber or Teflon would extend the range. For example, Linear, Inc., Philadelphia, Pa., offers O-rings made of silicone rubber for use at temperatures ranging from -65' to 400' F. This closure should be suitable for making pressure-tight joints between a metal and brittle materials such as glass or ceramics which can be formed by heating and/or grinding. LITERATURE CITED
Figure 2.
Disassembled (Left) and Assembled (Right) View of aTypical Seal
(1) Onnes and Braak, Comm. Univ. of Leyden, No. 166 (1923). RECEIVED Deoember 12, 1950.
Solubility of Methyl Bromide in Water and in Some Fruit Juices GILBERT P. HAIGHT, JR.' Bureau of Entomology and Plant Quarantine, United States Department of Agriculture, Honolulu, T . H. Absorption of methyl bromide, a fumigant, by fruit is of prime concern in insect control. Preliminary experiments showed large absorption by juices. No reliable value for the solubility of methyl bromide in water was found in the literature. As this is a fundamental property of methyl bromide, a determination was made, so the value would be available in the future for those using this material. The solubility of methyl bromide is greater in water than in the juice of pineapples, mangos, and papayas under comparable conditions.
I
THE course of studies on the effect of methyl bromide fumigation on larvae of the oriental fruit fly ( D a m s dorsalis Hendel) found in Hawaiian fruits, the question arose as t o whether absorption by the fruit might hinder penetration and thus account for low kills. As a preliminary test, methyl bromide gas was bubbled through the juice and found t o be absorbed in quantities in excess of 1 ml. of gas per ml. of juice. As the literature contains very little information on the solubility of methyl broIrj
1 Present address, Chemistry Department, George Washington University, Washington, D. C.
mide in aqueous solutions, it was decided to measure the solubility in water as well as in various juices for purposes of comparison. Lepigre ( 1 ) gives the solubility of methyl bromide as 5 t o 10 grams per liter of water at 18"C. Shepard ( 2 )gives the value 0.1 gram per 100 grams of water, with no experimental evidence or conditions. MATERIALS, APPARATUS, AND PROCEDURE
Distilled water and freshly obtained filtered fruit juices from ripe fruits were used throughout. T h e juices tested were: Fruit Pineapple Mango Papaya
PH 3.5 4
5
Density, G./Ml. 1.051 1.035
1.027
Technical grade liquid methyl bromide was used as the source of methyl bromide gas. The apparatus consisted simply of three traps in series, as illustrated in Figure 1. T h e first contained methyl bromide liquid, the second water, and the,third a weighed sample of the solvent being studied. The second and third traps were placed in a water bath to regulate the temperature. The first was kept
