US3208812A

US3208812A - Process and apparatus for dosing electrical devices

Info

Publication number: US3208812A
Application number: US253807A
Authority: US
Inventors: William L Brundige; Francis A Beane
Original assignee: Westinghouse Electric Corp
Current assignee: CBS Corp
Priority date: 1963-01-25
Filing date: 1963-01-25
Publication date: 1965-09-28
Anticipated expiration: 1982-09-28

Description

Sept. 28, 1965 PROCESS AND APPARATUS FOR DOSING ELECTRICAL DEVICES W. L. BRUNDIGE ETAL Filed Jan. 25, 1965 CARRIER GAS @EMICAL DRYER 47 Z u* FLUSH GAS FILL GAS FRE/V675 H. BEH/VE.

WILL/HM L. BRUNO/65.2:

United States Patent O 3,208,812 PROCESS AND APPARATUS FOR DOSING ELECTRICAL DEVICES William L. Brundige, West Caldwell, and Francis A.

Beane, Bloomfield, NJ., assignors to Westinghouse Electric Corporation, Pittsburgh, Pa., a corporation of Pennsylvania Filed Jan. 25, 1963, Ser. No. 253,807 10 Claims. (Cl. 316-21) This invention relates to electrical devices and has particular reference to an improved process and apparatus for dosing radiation-generating devices with volatile highly-reactive materials such as iodine or the like.

While the present invention can be used with advantage in making various types of electrical devices, it is especially adapted for use in the manufacture of so-called T3 quartz lamps recently developed and now being marketed. These lamps generate both visible and infrared radiations and can thus be used for lighting or heating purposes. The present invention is directed primarily to lamps that are intended for use as light rather than heat sources and are thus more aitected by bulb blackening.

Such lamps vare generally of tubular or pencil-like configuration and contain `a coiled filament that extends along the axis of the envelope and is held in this position by a series of tungsten-wire supports. In addition to the usual inert gas till these lamps are dosed with a precisely measured quantity of iodine which vaporizes when the lamp is operated. An iodine-tungsten cycle occurs within the lamp during use which keeps the bulb Walls substantially free from vaporized tungsten. Such lamps accordingly remain clean and have very good maintenance throughout their life and are very efficient. Radiation-generating devices of this type are disclosed in U.S. Patent 2,883,571, entitled Electric Incandescent Lamp, issued April 21, 1958 to E. G. Fridrich et al.

Since iodine is so active chemically the introduction of very carefully measured quantities into the envelopes of such lamps presents a very difficult problem. Var-ious schemes for dosing the lamp by mechanically transferring measured quantities of iodine granules or crystals into the envelope were tried but abandoned because they were too costly, too slow and damaged to stop cocks etc. used to protect the lamp from the atmosphere during the dosing operation.

As a result, the iodine content varied considerably from lamp to lamp, and, since the performance of the lamp is directly related to the amount of iodine sealed in the envelope, lamp quality could not be adequately controlled. This problem is aggravated by the fact that the iodine dosing must be accomplished during the exhaust and gaslling operations before the envelope is tipped off and must, therefore, be achieved Without introducing any solid or gaseous impurities into the envelope or opening it up to the atmosphere.

It is accordingly the general object of this invention to provide an eliicient means for introducing a predetermined quant-ity of a volatile material into the envelope of an electrical device without interfering with the other operations required to manufacture it.

Another object is the provision of a process for dosing a radiation-generating device with `a precisely controlled amount of a volatile material quickly and conveniently during the normal sequence of operations required to complete the manufacture of the device.

A further object is the provision of a process for dosing the envelope of a lamp or the like with predetermined amounts of iodine and a lill gas while it is protected from the atmosphere.

Still another object of the invention is the provision of a simple and inexpensime apparatus for carrying out the above-mentioned processes.

ice

The foregoing objects, and other advantages which will become apparent to those skilled in the art, are achieved in accordance with the present invention by introducing the volatile material into the envelope in the form of a vapor and directing it into heat-exchanging relationship with a region inside the lamp that has been cooled below the condensation temperature of the vapor. The vapor thus condenses at this region and, after the desired amount of the material has been deposited and the exhaust or gasiilling operations have been completed, the envelope is sealed.

In the case of the aforementioned T3 quartz lamps, the iodine vapor is entrained in a suitable inert carrier gas, such as nitrogen, and a controlled amount of the vapor-laden gas is dispensed into heat-exchanging relation with a cooled portion of the envelope. The fill gas (argon, for example) can also be used as the carrier 4gas in which case the envelope will be dosed and lled at the same time. Apparatus for -cooling the envelope to the proper temperature and injecting the vapor-laden carrier gas into the envelope through an attached tubulation by means of a hollow probe in accordance with one embodiment of the invention is also provided.

A better understanding of the invention will be obtained by referring to the sole figure in the accompanying drawing which illustrates one form of apparatus for introducing predetermined amounts of iodine and argon fill gas into the envelope of a tubular lamp.

The apparatus With specific reference to the drawing, the apparatus there shown is designed to dose a tubular T3 lamp 10 with a measured amount of iodine, and then fill it with la predetermined amount of argon while it is protected from the atmosphere. As illustrated, the lamp 10 comprises 'a pencil-like envelope 12 of quartz or t-he like that contains an axially-extending coiled tungsten filament 14. The filament is held in this position by a series of spaced tungsten-wire supports 16 and by press seals 18 at each end of the envelope in which the customary lead-in conductor Iassemblies 20 are embedded. The lamp 10 at this stage of fabrication is provided with an arm or exhaust tubulation 22 of quartz or the like that extends from the side of the envelope 12.

According to the illustrated apparatus embodiment the tubulated lamp 10 is held during the iodine-dosing and gas-tilling operations in the desired position by a head 24 that is fastened to a stationary support 25. The head 24 is .provided with an axially extending aperture 26 and a laterally extending port 27 that communicates with the aforesaid aperture. A suitable apertured sealing means such as a compression-rubber assembly 28 is mounted on the upper face of the head 24 and a second compressionrubber assembly 30 is mounted on the lower face of the head. The openings in the aforesaid compression-rubber assemblies are aligned with the aperture 26 in the head 24 so that, when the compression-rubber assemblies are open, a vertical passageway is provided that extends completely through the head. Such compression-rubber assemblies are well known in the art and are so constructed that they effect an airtight seal with an inserted tubulation or plug when the assemblies ar-e actuated by moving the

levers

29 and 31, respectively.

The evacuation, iiushin-g and filling of the lamp 10 loaded into the head 24 is accomplished by connecting the :laterally extending port 27 with a suitable conduit 32 which, lin turn, is joined to three

branch conduits

34, 36 and 38 that connect witha supply of iiush gas such as nitrogen, a suitable vacuum system (not shown) and a -supply of iill gas such as argon, respectively. These ush, vacuum and iill gas lines are provided with

suitable valves

35, 37 and 39, respectively, so that the lamp 10 may be sequentially ushed and evacuated and then iilled by operating the proper valves.

1t may be desirable, or even preferable in some cases, to ush the lamp with the same type of gas used as the fill gas. This would further reduce the manufacturing cost of the lamp since it eliminates the need for a separate flush -gas line and system and simplifies the entire operation.

It should be borne in mind that since no chemical getters are used in the lamp, it is extremely important that only dry pure gas be used as the carrier, flush and fill gases to avoid contaminating and ruining the lamp.

The loaded lamp is dosed With a predetermined amount of iodine in accordance with the present invention by means of a dosing system that is coupled to the lamp at the proper time. In the embodiment shown in the drawing, the major component of this system is a doser unit 40 which comprises an elongated enclosure, such as a glass tube 42, and an attached hollow needlelike pr-obe 60 that is insertable into the head 24. The doser tube 42 has an -opening 43 near its closed end and a second opening 44 at its opposite end. The tube is packed with the following materials which are separated from each other and arranged in the order in which they are named, starting from the closed end of the tube and proceeding toward its mouth; a filling of suitable filter material 45 such as glass wool or the like, a lling or reservoir of loosely packed iodine crystals or granules 46, a filling of loosely packed beads of a suitable chemical dryer 47 that does not react with either iodine or the carrier gas that is used, and a second lling of glass wool or other suitable filter material 48. A removable plug 49 is inserted into and closes the mouth of the doser tube. As shown, the compartment containing the filling 45 of filter material communicates with the opening 43 and the other chamber lled with filter material 48 communicates with the other opening 44 in the tube 42.

The opening 43 is connected by means of a conduit 50, a valve 52 and a tubing 54 to a supply of a suitable carrier gas, such as nitrogen or argon, that does not react with iodine. The operation of the valve 52 in the illustrated embodiment is controlled by an electrical timer 56 so that the carrier gascan be fed through the dosing unit 40 for a predetermined length of time and at a preselected pressure and temperature.

The other opening 44 in the doser tube 42 is provided with a nipple 57 that is hermetically joined by means of a collar 58 to the aforementioned probe 60. The probe has a diameter that is considerably smaller than both the bore of the lamp tubulation 22 and the aperture 26 in the head 24, and it is of suicient length to extend through the head and the tubulation into the partly fabricated lamp 10 loaded into the head. There is, accordingly, a gap or space 61 between the inserted probe 60 and the wall of the tubulation 22 through which iiush gas, and carrier gas that has been purged of iodine vapor, can be vented to the atmosphere through the head 24 and the upper compression-rubber assembly 28 when the latter is opened, as shown in the drawing.

According to the form lof the invention illustrated in the drawing, cooling of the envelope 12 to a predetermined temperature below that of the iodine vapor entrained in the carrier gas is accomplished by immersing the lamp 10 in a container 64 lled with a suitable liquid coolant such as ice water 65. The container is mounted on a suitable support 68 that is located below and is movable toward and away from the head 24, as indicated by the arrow in the drawing, so that a lamp loaded in the head can be immersed in and subsequently withdrawn from the container of ice water.

In order to avoid localized supercooling of the envelope -12 and resultant variations in the amount of iodine vapor condensed into the lamp 10, a baffle (not shown) is desirably mounted within the container 64 to prevent the pieces of ice 66 from contacting the envelope. S-alt may be also added to the ice water and the water stirred to 4 maintain it at a uniform temperature of about 0 C. ill" C.

The doser tube 42, nipple 57 and collar 58 are desirably fabricated from glass or quartz or some other vitreous material that does not react with iodine. To avoid breakage the probe 60 is preferably fabricated from a metal such as No. 316 stainless steel or the like that is not readily corroded by iodine. Tantalum and platinum, although costly, would be preferable since they are even less subject to attack. The metal portions of the head 24 and all other parts of the system which are made of metal and might come in contact with iodine vapor are also made from a similar material.

It is desirable to pass the iodine-vapor-laden carrier gas through a chemical dryer 47 to remove moisture from the Vapor which, if introduced into the lamp, would cause short life. Phosphorus pentoxide has given satisfactory results and, surprisingly, does not even discolor the iodine vapor. Other suitable drying agents are calcium chloride (anhydrous) and calcium nitrate, and mixtures thereof. An adsorbent material such as sodium zeolite or potassium zeolite that getters moisture by a molecular sieve type action can also be used. These materials are well known and are disclosed in U.S. Patent Nos. 2,882,243 and 2,882,244. Such materials aiord the additional advantage of gettering trace amounts of oxygen that may be present in the carrier gas and would otherwise be introduced into the lamp during the dosing operation.

The process In general, dosing of the partly-fabricated lamp 10 is accomplished in accordance with the illustrated embodiment of the present invention by rst entraining predetermined amounts of iodine vapor in the carrier gas by passing the latter through the dosing unit 40 at a controlled rate of flow while the doser is maintained at approximately room temperature (20 C.). If nitrogen is the carrier gas, the iodine-vapor-laden nitrogen is then injected into the cooled lamp 10 through the probe 60 in such a manner that the gas impinges upon and is thus placed in heat-exchanging relationship with the part of the envelope wall located substantially opposite the mouth of the tubulation 22. A predetermined percentage of the entrained iodine vapor condenses onto the chilled envelope wall and a layer or lm 62 of iodine forms at this point on the envelope surface, as illustrated in the drawing. Since the vapor pressure of iodine at 20 C. is about 0.20 mm. and drops to about 0.01 mm. at 10 C., the percentage of the entrained iodine vapor which condenses inside the cooled envelope is controlled by the temperature differential that exists between the vapor and the cooled portion of the envelope.

The nitrogen from which iodine vapor has been removed is vented to the atmosphere through the space 61 between the probe 60 and the tubulation 22 and then through the head 24 and the open compression-rubber assembly 28. This gas ow, in conjunction with the ush gas that is continually fed into the lamp during the dosing operation, maintains a positive pressure in the aforesaid opening and forms a dynamic seal or barrier that protects the loaded lamp 10 from the atmosphere. The vapor-laden nitrogen is fed into the lamp 10 at a preselected pressure and for a preselected time (set on the timer 56) so that a precisely-controlled amount of iodine 62 is introduced into the lamp.

The probe is then withdrawn, the compression assembly 28 is closed, the envelope 12 (while still in its cooled condition) evacuated and lled with argon, and the tubulation 22 sealed at a point adjacent the envelope thus completing the fabrication of the lamp.

If argon is used as the carrier gas instead of nitrogen, then dosing andflling of the lamp 10 will, of course, be accomplished simultaneously. In this case, the probe 60 is only partly withdrawn from the tubulation 22 after the dosing and filling operations are completed and the tubulation is tipped off at a point adjacent the envelope while the vapor-laden argon is still flowing through the probe and out of the open end of the tubulation. Since the lamp is already illed with argon the iodine-vaporladen argon will flow out through the space 61 rather than into the envelope and no more iodine will condense inside the lamp. The amount of iodine deposited in the lamp is thus accurately controlled by the dosing operation in the same manner as when it is carried out independently of the filling operation.

Specific example Following is a specic example of a schedule of operations for sequentially iodine-dosing and gas-filling a T3 quartz lamp or the like according to the teachings of the present invention using nitrogen as the carrier gas and the apparatus illustrated in the drawing:

(1) Insert the tubulated lamp 10 into the head 24, close the lower compression assembly 30 and seal oif the upper assembly 28 by means of a glass plug (not shown).

(2) Alternately exhaust the lamp down to 10 microns or less and then flush with an inert gas such as nitrogen at a pressure of 100 millimeters above atmospheric pressure by manipulating

valves

35 and 37, and continue for three cycles.

(3) Heat the lamp to a temperature lof at least 750 C. for five minutes by placing it in an oven and alternately flush and exhaust for three cycles (during the first two cycles exhaust to a pressure of about 10 microns and during the last cycle to about five microns or less).

(4) Cool the envelope to a temperature of about 0 C ilu C. by immersing it in the container 64 of ice water.

(5 Open valve 35 and ush nitrogen at the aforesaid pressure through the cooled envelope until after the dosing operation (step 6 below) is completed.

(6) Open the upper compression-rubber assembly 28 and insert doser needle or probe 60 through the head 24 and tubulation 22 and into the envelope 12 until the tip of the probe is proximate the envelope wall. Flush the nitrogen carrier gas through the doser 40 for a predetermined length of time at about 100 millimeters above atmospheric pressure until the desired amount of iodine condenses on the cooled envelope wall. In the specific case of a 500 watt tubular heat lamp approximately 3.15 inches long and having an O.D. of 3A; inch, the vaporladen nitrogen is injected into the envelope for approximately seconds when nitrogen at approximately room temperature is fed through the doser at the aforementioned pressure and 12 cc. of iodine crystals are present in the doser, which is also maintained at room temperature.

(7) After the iodine dosing operation has been completed, withdraw the dosing probe 60 from the head 24 and re-insert the plug and seal off the upper compressionrubber assembly 28 from the atmosphere.

y(8) Exhaust the lamp 10 to about 2() microns and flush once with nitrogen to a till pressure of about 50 to 100 millimeters.

(9) Exhaust the lamp to about 2O microns and flush once with argon to a ll pressure of about to 50 millimeters.

(10) Finally, exhaust the lamp to 10 microns, or less, and then ll with argon to about 680 millimeters pressure by operating

valves

37 and 39.

(11) Remove the lamp from the ice water and tip off the tubulation 22 at a point about 5 millimeters, and preferably less, from the envelope.

If salted ice water has been used, the lamp is then washed in water and dried.

Summary It will be appreciated from the foregoing that a process and apparatus for introducing a predetermined amount of volatile material and an inert gas into the envelope of an electric lamp or the like has been provided which not only facilitates the manufacture of the lamp, but avoids intolerable variations in the dosage from lamp to lamp and thus improves the lamp quality.

Moreover, the dosing process and apparatus are such that this operation can ybe carried out during the regular sequence of operations required to complete the lamp thus further reducing its manufacturing cost.

While one embodiment has been illustrated and described, it will be appreciated that various structural and procedural modifications can be made without departing from the spirit and scope of the invention.

-For example, a cold trap may be inserted into the vacuum line to protect the associated Valves and the exhaust system from iodine vapor and corrosion, and a jet of a gaseous coolant or a refrigerator unit can be used to chill the part of the envelope located opposite the tubulation instead of immersing the entire envelope in a liquid coolant as shown and described.

We claim as our invention:

l. In the manufacture of a radiation-generating device having an envelope with a tubulation, the process of dosing the envelope with a volatile material and lling it with an inert gas, which process comprises,

cooling the portion of said envelope located substantially opposite the mouth of said tubulation to a predetermined temperature at which vapor from said volatile material will condense,

placing a quantity of said volatile material in a stream of an inert carrier gas, regulating the temperature of said volatile material and the rate of flow of the carrier gas to cause the volatile Imaterial to vaporize and the resulting vapor to be entrained in the stream of carrier gas at a controlled rate, injecting the vapor-laden stream of carrier gas into the envelope through the tubulation and into impinging relationship with the cooled portion of the envelope so that the entrained vapor condenses thereon,

venting the carrier gas that has impinged upon the cooled portion of the envelope to the atmosphere,

maintaining the flow of vapor-laden carrier gas into said envelope for a predetermined period of time so that a preselected amount of said volatile material condensed on the cooled portion of said envelope,

evacuating said envelope and lling it with a predetermined amount of inert gas through said tubulation while the aforesaid portion of said envelope is still in its cooled condition and the volatile material is condensed thereon, and then sealing-olf the tubulation at a point adjacent said envelope.

2. The dosing and gas-filling process as set forth in claim 1 wherein the stream of vapor-laden carrier gas is treated to remove moisture therefrom prior to being dispensed into the envelope.

3. The dosing and gas-filling process as set forth in claim 2 wherein; said volatile material comprises iodine, and the stream of vapor-laden carrier gas is purged of moisture prior to being dispensed into the envelope by exposing it to a drying agent selected from the group consisting of calcium chloride, calcium nitrate, phosphorous pentoxide, sodium zeolite, and potassium zeolite,

4. In the manufacture of a radiation-generating device having an envelope with a vitreous tubulation, the process of dosing the envelope with iodine and filling it with an inert gas, which process comprises,

im-mersing the envelope in a liquid coolant to cool it to a predetermined temperature at which iodine vapor will condense,

passing nitrogen through an enclosure that contains iodine and is maintained at a predetermined temperature above that of the cooled envelope,

controlling the rate of flow of nitrogen through said enclosure so that a predetermined amount of iodine vapor is entrained in the flowing nitrogen,

injecting the vaporladen nitrogen into the envelope through said tubulation and impinging it off the inner surface of said cooled envelope for a predetermined period of time so that the iodine vapor condenses thereon,

removing the nitrogen from said envelope through a portion of said tubulation that is isolated from the portion carrying the vapor-laden nitrogen,

maintaining the flow of vapor-laden nitrogen into said envelope for a predetermined period of time so that a preselected amount of iodine condenses therein,

evacuating and filling said envelope with a predetermined amount of inert gas through said tubulation while the envelope is still immersed in the coolant and the iodine is in a condensed state, and then tipping off said tubulation to seal the condensed iodine and lill gas in said envelope.

5. The iodine dosing and gas filling process as set forth in claim 4 wherein,

said envelope is cooled to a temperature approximately 20 C. below that of the iodine vapor, and

the iodine-vapor-laden nitrogen is exposed to phosphorous pentoxide to remove moisture therefrom before being injected into said envelope.

6. The iodine-dosing and gas-filling process as set forth in claim 4 wherein,

said envelope is immersed in ice water and is thus cooled to a temperature of approximately C., the vaporladen nitrogen is exposed to a drying agent before being injected into said envelope to remove moisture therefrom, and

the dried vapor-laden nitrogen is also filtered prior to -being injected into the cooled envelope to remove solid impurities therefrom.

7. Apparatus for dosing a radiation-generating device or the like with a predetermined amount of a vaporizable material, said device having an envelope with a tubulation, which apparatus comprises,

a head having an aperture therethrough,

a first sealing means carried by vsaid head and adapted to receive and effect an air-tight seal with the tubulation attached to said envelope,

a second sealing means carried by said head and located opposite said first sealing means and in alignment therewith and with the aperture in said head,

means for cooling the portion of said envelope located opposite said tubulation,

an enclosure for a reservoir of the vaporizable material,

an elongated hollow probe hermetically attached to said enclosure and communicating with an opening there- 1n, said probe being insertable into said second sealing means and dimensioned to fit loosely in and extend through the aperture in said head and the tubulation attached to an envelope loaded in said head, conduit means connected to another opening in said enclosure for passing an inert gas through said enclosure and probe, and means for controlling the iiow of inert gas through said enclosure and probe. 8. Dosing apparatus as set forth in claim 7 wherein, said means for controlling the gas flow comprises a timer-controlled valve in said conduit means, and said enclosure contains filter means located on the upstream side of the opening that communicates with said probe. 9. Apparatus for dosing a radiation-generating device such as a tubular lamp or the like `with a predetermined amount of a vaporizable material, said device having an envelope with an attached tubulation, which apparatus comprises,

a head'having an aperture that extends through said head along a vertical axis and communicates with a laterally extending port,

a first compression-rubber assembly on the lower face of said head adapted to receive and effect an air-tight seal with the tubulation of a lamp loaded in said head,

a second compression-rubber assembly on the upper face of said head and aligned with said first compression-rubberr assembly and the aperture through said head,

a container for a liquid coolant adapted to receive said lamp,

means for effecting relative movement between said head and container and immersing a lamp loaded in said head in said coolant,

an elongated enclosure for containing a reservoir of the vaporizable material and a segregated quantity of a chemical drying agent,

said enclosure having an opening at each end,

an elongated hollow probe hermetically coupled to said enclosure and communicating with one of said openings,

said probe being insertable into said second compression-rubber assembly and being of such cross-sectional dimension and length that it loosely fits in and extends through the aperture in said head and the tubulation of a lamp loaded in said head,

conduit means for connecting the other opening in said enclosure to a supply of inert carrier gas,

a timer-controlled valve in said conduit means for regulating the flow of inert carrier gas through said enclosure and probe, and

conduit means for connecting the port in said head to an evacuating system and to a supply of inert flushing and a ll gas.

10Q In the manufacture of an electric lamp or similar device having an envelope, the process of dosing the envelope with a volatile chemically-active material and filling it .with an inert gas, which process comprises,

cooling a portion of said envelope to a predetermined temperature at which vapor from said material will condense,

passing an inert carrier gas through an enclosure containing said volatile material,

controlling the temperature of said volatile material and the rate of owk of said carrier gas through said enclosure so that said material vaporizes at a predetermined rate and a controlled amount of vapor is entrained in said carrier gas,

introducing the vapor-laden carrier gas into the envelope and directing it into heat-exchanging relationship with the cooled portion of the envelope to cause entrained vapor to condense thereon,

maintaining the ow of vapor-laden carrier gas into said envelope for a predetermined period of time so that a preselected amount of the volatile material condenses onthe cooled envelope portion,

evacuating said envelope and filling it with a predetermined amount of'inert gas while the aforesaid portion of the envelope is still in its cooled condition and the volatile material is condensed thereon, and then sealing the envelope to retain the gaseous filling and condensed volatile material therein.

References Cited by the Examiner UNITED STATES PATENTS 1,789,556 l/31 Machlett 316-20 X 3,093,430 6/ 63 Wiley 316-24 FRANK E. BAILEY, Primary Examiner.

Claims

1. IN THE MANUFACTURE OF A RADIATION-GENERATING DEVICE HAVING AN ELVELOPE WITH A TUBULATION, THE PROCESS OF DOSING THE ENVELOPE WITH A VOLATILE MATERIAL AND FILING IT WITH AN INERT GAS, WHICH PROCESS COMPRISES, COOLING THE PORTION OF SAID ENVELOPE LOCATED SUBSTANTIALLY OPPOSITE THE MOUTH OF SAID TUBULATION TO A PREDETERMINED TEMPREATURE AT WHICH VAPOR FROM SAID VOLATILE MATERIAL WILL CONDENSE, PLACING A QUANTITY OF SAID VOLATILE MATERIAL IN A STREAM OF AN INERT CARRIER GAS, REGULATING THE TEMPREATURE OF SAID VOLATILE MATERIAL AND THE RATE OF FLOW OF THE CARRIER GAS TO CAUSE THE VOLATILE MATERIAL TO VAPORIZE AND THE RESULTING VAPOR TO BE ENTRAINED IN THE STREAM OF CARRIER GAS AT A CONTROLLED RATE, INJECTING THE VAPOR-LADEN STREAM OF CARRIER AS INTO THE ENVELOPE THROUGH THE TUBULATION AND INTO IMPINGING RELATIONSHIP WITH THE COOL PORTION OF THE ENVELOPE SO THAT THE ENTRAINED VAPOR CONDENSES THEREON, VENTING THE CARRIER GAS THAT HAS IMPINGED UPON THE COOLED PORTION OF THE ENVELOPE TO THE ATMOSPHERE, MAINTAINING THE FLOW OF VAPOR-LADEN CARRIER GAS INTO SAID ENVELOPE FOR A PREDETERMINED PERIOD OF TIME SO THAT A PRESELECTED AMOUNT OF SAID VOLATILE MATERIAL CONDENSED ON THE COOLED PORTION OF SAID ENVELOPE, EVACUATING SAID ENVELOPE AND FILLING IT WITH A PREDETERMINED AMOUNT OF INERT GAS THROUGH SAID TUBULATION WHILE THE AFORESAID PORTION OF SAID ENVELOPE IS STILL IN ITS COOLED CONDITION AND THE VOLATILE MATERIAL IS CONDENSED THEREON, AND THEN SEALING-OF THE TUBULATION AT A POINT ADJACENT SAID ENVELOPE.