US3026187A - Vapor density measuring apparatus - Google Patents

Description

March 20, 1962 J, H. ROBERTSON VAPOR DENSITY MEASURING APPARATUS Fil ed Nov. 13, 9

INVENTOR JUDSQN H. ROBERTSON ar/(M0 2, fwa m, 934% ATTORNEY'J7 FIG. 4..

" 3,026,187 Ice Patented Mar. 20, 1962 3,026 187 VAPOR DENSITY NIEXSURING APPARATUS Judson H. Robertson, Knoxville, Tenn., assignor to The University of Tennessee Research Corporation, Knoxville, Tenn., a corporation of Tennessee Filed Nov. 13, 1959, Ser. No. 852,653 Claims. (Cl. 23292) This invention relates to vapor density measuring apparatus and more particularly to such apparatus in which the sample to be measured is vaporized and the air displaced by the vaporization thereof measured in the manner proposed by Victor Meyer to determine the vapor density of the sample.

In the Well-known Victor Meyer method of determining vapor density, a weighed sample of the liquid to be measured is vaporized and the volume of air displaced from the vaporization unit is measured under the prevailing conditions of temperature and pressure in the room to determine the vapor density of the sample. If vapor from the sample passes from the vaporizing apparatus or condenses therein the measurements are vitiated. The vaporization unit proposed by Victor Meyer in its usual form is made quite long to prevent such condensation or loss of vapor and is therefore rather cumbersome. Even with conventional forms of apparatus vapor can be lost from the vaporizing unit and condensed with the displaced air to thus produce errors in the vapor density determination.

Various modifications have been suggested of the Victor Meyer apparatus to obtain compactness and to eliminate vapor condensation but these modifications have undesirable features. In one such modification the distance the vapor travels before leaving the vaporizing unit is increased by sealing a J-shaped delivery tube through the bottom of the vaporization bulb with the short end of the tube extending almost to the top of the vaporization bulb, the long end of the tube extending up through the outer heating jacket. The volume of the vaporization bulb in this apparatus is largely dead space and the vapors must be swept out between successive uses of the apparatus. The long leverage of the exit end of the tube makes the tube very susceptible to breakage of the bottom seal when assembly or disassembling the apparatus.

In another modification of the Victor Meyer apparatus a tube is employed in the vaporizer through which the sample is introduced. This tube projects downward through a series of bulbs forming annular spaces along the seals between the bulbs. The escaping vapor or air expands successively through the small spaces giving a steady flow of air into the measuring buret. Escape of vapor is minimized by the large capacity of the bulbs. This apparatus is particularly adapted for the study of molecular weight of petroleum constituents by the method of limiting density but is not advantageously used for regular vapor density measurements.

Another modification of the Victor Meyer apparatus employs a central vaporization tube which extends downwardly into and almost to the bottom of the inner jacketed compartment of the vaporizer. The sample bulb is fastened at the top of this central tube so that when crushed the vapor must pass downward through the central tube and then upward around it to the top before reaching the unjacketed part of the apparatus. While this apparatus is conveniently and simply constructed it is possible for vapor to escape therefrom with the air to Vitiate the measurements of vapor density.

It is therefore the object of the present invention to provide a modification of the Victor Meyer vapor density measuring apparatus which is almost completely free from the danger of vapor condensation and escape; which is compact; which is durable; and which is convenient and easy to use.

Other and further objects of the present invention will appear from the following description of an illustrative embodiment thereof.

The vapor density measuring apparatus of the present concept is capable of various mechanical embodiments one of which is shown in the accompanying drawing and is described hereinafter to illustrate the invention. This illustrative embodiment of the present invention should in no way be construed as defining or limiting the same.

In the accompanying drawings, in which like reference characters indicate like parts, FIG. 1 is an elevational view of an illustrative embodiment of the present concept showing the vaporization chamber surrounded by a spaced outer jacket with the exit tube from the vaporization chamber coiled around the outside of the vaporization chamber and within the outer jacket;

FIG. 2 is a detail of a portion of the embodiment of FIG. 1 on the lines 22 thereof;

FIG. 3 is an elevational view of the device employed with the embodiment of FIG. 1 for breaking the sample bulb and for reducing turbulence and convection currents in the vaporization chamber; and

FIG. 4 is a view of the assembled embodiment of FIGS. 1 and 3 mounted on a stand and ready for use.

Referring now to the several figures, 10 is an outer jacket of elongated cylindrical form of suitable material such as Pyrex glass having outlet 11 formed at the top thereof for connection to any suitable condenser, not shown, and provided with a mouth 12. A vaporizing chamber 13, also of Pyrex glass, is sealed within jacket 10 beneath mouth 12 along seal line 14. Chamber 13 is spaced from and extends within jacket 10 and has bottom 15 spaced from and adjacent to bottom 16 of jacket 10. Exit tube 17 opens into the upper end of chamber 13 and is sealed to the wall thereof at 18. Tube 17 is wound downwardly around the outside of chamber 13; is formed in a turn at 19; and then is wound upwardly around the outside of chamber 13 in the helical space between the downward turns thereof. Tube 17 passes out through the upper portion of jacket 10 at 20 and is sealed thereto to form a vapor tight seal. Exits tube 17 terminates in an end portion 21 for connection to a suitable measuring buret, not shown.

The device for breaking the bulb containing the sample to be vaporized is seen in FIG. 3. This breaking device includes a glass tube 22 which is of sufficient length to extend to adjacent the bottom of vaporizing chamber 13, as seen in FIG. 4. Tube 22 passes through a cork or seal 23 which forms a vapor tight fit in mouth 12. A wire 24 is secured adjacent the upper end of tube 22 and within tube 22, as at 25, and the upper end of tube 22 is suitably sealed against the escape of vapor by any suitable seal here shown as a length of rubber tubing 26 embracing tube 22 and closed by a length of glass rod 27 mounted therein. A sample bulb 28 is hooked to or suitably secured to the lower end of wire 24 as at 29. A plurality of spaced perforated discs 30 are mounted on tube 22 and form a loose fit in vaporizing chamber 13 to prevent turbulence of vapor flow and convection currents in vaporizing chamber 13.

When in use, the apparatus of the present concept is method as shown in FIG. 4 on a stand 31 having an upwardly extending support 32 which is provided with a clamp 33 carrying a suitable heat diffusing element 34. Any suitable source of heat such as a Bunsen burner, not shown, is supported on stand 31 beneath element 34. Upright 32 carries a second clamp 35 which supports jacket 10 between forks 36. When the apparatus is to be used a suitable heat conducting liquid is placed in jacket 10 the steam or vapor from which heats vaporizing chamber 13. If the heat conducting liquid is volatile mouth 11 is connected to a suitable condenser, not shown,

and the conducting liquid is heated. The material to be tested is then placed in sample bulb 28 which is then sealed, Weighed and connected to wire 24. Tube 22 is inserted into vaporizing chamber 13 with seal 23 making a vapor tight fit with mouth 12. Bulb 28 is then crushed by manipulation of wire 24 at the flexible joint 25 and the sample is vaporized in chamber 13 with the vapors passing outwardly therefrom and into the tube 17. Displaced air passing out of tube 17 through extension 21 thereof is then led to any suitable measuring buret, not shown, and vapor density measurements are completed in wellknown manner.

Because of the great length of exit tube 17 compared to the length of vaporizing chamber 13, the air displaced by the vaporization of the sample can be readily measured Without loss of vapor from the apparatus and without condensation of vapor. Exact and accurate measurements of vapor density of the sample can therefore be obtained. In a representative embodiment of this apparatus jacket 10 may have an overall height of 31 cm.; an outside diameter of cm.; and exit tube 17 may have an inside diameter of 6 cm. and an over-all length of 2 111. (6 /2 feet).

Typical student results are given in Table 1. Routine vapor density determinations by students using the apparatus of the present invention as described above have been less subject to erratic errors than with prior known forms of the apparatus:

TABLE 1 Illustrative Student Data, Using Ethylaniline (B.P. 204) as Boiling Liquid Substance Benzene (78.11)

It should now be apparent to one skilled in the art that the vapor density measuring apparatus of the present invention in every way satisfies the several objectives described above.

Changes in or modifications to the above-described illustrative embodiment of this invention may now be suggested to those skilled in the art without departing from the present inventive concept. Reference should therefore be had to the appended claims to determine the scope of this invention.

What is claimed is:

1. In a vapor density measuring apparatus, a jacket, a mouth in said jacket, a vaporizing chamber in said jacket communicating with said month, an exit tube sealed to and opening into said chamber adjacent said mouth and wrapped downwardly around and then upwardly around the outside of and extending substantially the length of said chamber Within said jacket, said exit tube being sealed to and passing outwardly through said jacket adjacent said mouth and means for introducing a sample to be tested into said chamber said means closing said mouth with a vapor tight seal.

2. Apparatus as described in claim 1, said jacket being an elongated hollow cylinder closed at one end with said mouth at its opposite end, said chamber being an elon gated hollow cylinder closed at one end adjacent to and spaced from the closed end of said jacket and sealed at its other end to said jacket adjacent said mouth.

3. Apparatus as described in claim 2 in which said means comprises a hollow tube, a wire extending through said tube, a stopper on said tube adjacent an end thereof for sealing said mouth, means for closing said tube adjacent said stopper and a sample bulb carried by said wire at the end of said tube away from said stopper.

4. Apparatus as described in claim 3 including spaced perforated discs mounted on said tube and forming a loose fit in said chamber. I

5. Apparatus as described in claim 1 including means for introducing a heating liquid into said jacket around said chamber and around said tube.

References Cited in the file of this patent UNITED STATES PATENTS 1,034,170 Vanier a July 30, 1912

Claims (1)

1.IN A VAPOR DENSITY MEASURING APPARATUS, A JACKET, A MOUTH IN SAID JACKET, A VAPORIZING CHAMBER IN SAID JACKET COMMUNICATING WITH SAID MOUTH, AN EXIT TUBE SEALED TO AND OPENING INTO SAID CHAMBER ADJACENT SAID MOUTH AND WRAPPED DOWNWARDLY AROUND AND THEN UPWARDLY AROUND THE OUTSIDE OF AND EXTENDING SUBSTANTIALLY THE LENGTH OF SAID CHAMBER WITHIN SAID JACKET, SAID EXIT TUBE BEING SEALED TO AND PASSING OUTWARDLY THROUGH SAID JACKET ADJACENT SAID MOUTH AND MEANS FOR INTRODUCING A SAMPLE TO BE TESTED INTO SAID CHAMBER SAID MEANS CLOSING SAID MOUTH WITH A VAPOR TIGHT SEAL.

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