Method For Purging And Filling Multiple Glazed Units

Abstract

A method for purging and filling a multiple glazed unit with a fluorocarbon gas in which the unit is supported so that its pore hole is located in an upper disposed region of the unit and, while so supported, the gas is injected into the unit and air is simultaneously displaced therefrom.

Parent Case Text

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation-in-part of application Ser. No. 845,988, filed July 30, 1969, now abandoned.

Description

BACKGROUND OF THE INVENTION:

This invention relates to a method for purging and filling multiple glazed, insulating units. More particularly, the present invention relates to an improved method for purging and filling all-glass multiple glazed units with a fluorocarbon gas and, thereafter, sealing the gas within the units to improve their insulation effectiveness, thus reducing heat loss due to indoor and outdoor temperature differentials.

The term fluorocarbon, as used herein, is intended to include all normally gaseous fluorine containing hydrocarbons having one to four carbon atoms, including compounds which may contain other halogen and/or hydrogen atoms in addition to the fluorine present. Included among the fluorocarbon compounds that are contemplated are: tetrafluoromethane, trifluoromethane, chlorotrifluoromethane, hexafluoroethane, bromotrifluoromethane, chlorodifluoromethane-chloropentafluoroethane, chlorodifluoro-methane, chloropentafluoroethane, dichlorodifluoromethane, 1,1-difluoroethane, vinyl fluoride, vinylidene fluoride and mixtures thereof. These compounds are sold as "Freon" fluorocarbons by E. I. DuPont DeNemours & Company.

One commercially used process for making all-glass multiple glazed units is broadly disclosed in U.S. Pat. No. 2,624,979. This process proceeds by supporting two superposed sheets of glass, with the upper sheet slightly larger than the lower sheet, in slightly spaced relationship to each other, heating the margins of the upper sheet until they droop and become welded or fused with the margins of the lower sheet, pulling the upper sheet upwardly to provide a chamber between the sheets, and abruptly increasing the air pressure within the unit to effect filleting of the welded connection between the sheets. The units have a least one pore opening either in a face or an edge of the unit through which air under pressure is introduced between the sheets to effect filleting and, also, which thereafter allows for equalization of the pressure of the air within the unit with atmospheric pressure during annealing and cooling of the unit.

Subsequent to cooling the unit, additional treatment thereof includes purging and filling the unit with dry air or gas and hermetically sealing the unit. In the past, this purging and filling operation has generally been accomplished while supporting the unit on edge in a vertical position and purging and filling the unit through a pore hole located at or near the bottom or supporting edge of the unit.

It has been discovered, however, that when it is desired to purge and fill these units with a low conductive, fluorocarbon gas, use of the above-mentioned technique requires too great a time to displace the air from within the unit and excessive amounts of the purging and filling gas are wasted by release of this gas to the work area surrounding the unit.

The present invention is directed toward ameliorating or overcoming the foregoing problems. In accordance with the present invention, each unit to be purged and filled with a fluorocarbon gas is supported with a pore hole residing in the upper disposed region of the unit. The fluorocarbon gas is then introduced or injected into the interior of the unit through the pore hole while the air within the unit is simultaneously displaced therefrom through the same pore hole. By proceeding in the above manner, it has been demonstrated that multiple glazed units can be purged and filled to provide upwards of 85 - 100 percent by volume of a fluorocarbon gas in the space between the glass sheets at least three to four times faster and with minimal wastage or release of gas to the surrounding environment than was previously possible when purging and filling by the prior art technique.

The foregoing and other objects, features and advantages of the present invention will become more apparent from the description that follows when taken in conjunction with the drawing, in which:

FIG. 1 is a perspective of a plurality of vertically disposed all-glass, multiple glazed units being purged and filled in accordance with this invention; and

FIG. 2 is a perspective of a plurality of horizontally disposed all-glass, multiple glazed units being purged and filled in accordance with this invention.

Depicted in FIG. 1 are a plurality of all-glass, multiple glazed units 10 comprised of a pair of glass sheets 12 and 14 that are welded together about their marginal edges. As illustrated, one of the glass sheets, 12, of each unit 10 is provided with a pore hole or purge hole 16 in a marginal edge portion thereof and in communication with the interior of the unit.

In accordance with the present invention, units 10 are each supported on edge in a vertical position on rack 18 so that the pore hole 16 is located in the upper disposed region of the unit. Also shown is a conduit or header 20 for the conduction of a fluorocarbon gas to the vicinity of rack 18 and units 10. Header 20 is provided with a plurality of flexible plastic tubes 22 of smaller outside diameter than the diameter of pore holes 16 and which, as shown, are inserted in pore holes 16 and suitably connected to the header 20 to conduct the fluorocarbon gas under pressure from the header to the interior of each of the multiple glazed units. As illustrated by the dashed arrows in FIG. 1, the fluorocarbon gas is conducted downwardly into the lower disposed region of units 10 to purge and fill each unit, and the air which is thereby displaced from the unit, illustrated by the solid arrows, escapes therefrom to the work area adjacent the units from the generally annular space between tubes 22 and the side walls of pore holes 16.

Shown in FIG. 2 is an alternate embodiment of this invention wherein like numerals to those used in FIG. 1 have been employed to designate like parts throughout the same. In FIG. 2, the units 10 are shown supported on one side thereof in a horizontal position on a suitable table or conveyor support 24 so that pore hole 16 is located in the upper glass sheet or upper disposed region of each unit. As is again illustrated by the dashed arrows in FIG. 2, the fluorocarbon gas is conducted to the lower disposed region of units 10 to purge and fill each unit and the air which is thereby displaced from the unit, illustrated by the solid arrows, escapes therefrom to the work area adjacent the units from the generally annular space between tubes 22 and the side walls of pore holes 16.

To illustrate the improvement achieved by the practice of the present invention, all-glass multiple glazed units of several different sizes were purged and filled on the same equipment using the "conventional" technique of purging and filling from the lower disposed region of the units and the "improved" technique of this invention of purging and filling from the upper disposed region of the units. For any given size unit, the air space thickness dimension from unit to unit was the same. The results of these tests are as follows, with the purging and filling technique in each case being indicated as "conventional" or "improved" in accordance with the foregoing description of these techniques:

TABLE I

Purging and Filling with Chlorodifluoromethane

Gas Purge Concentration Gas and of Purging Purging Line Fill Unit Size and Filling and Filling Pressure Time (Width .times. Gas in Unit Technique (psi) (min.) Length) (% by __________________________________________________________________________ Volume) Conventional 40 2 16".times.68 " 62.5 Conventional 40 6 16".times.68" 64 Conventional 40 10 16".times.68" 65.5 Improved 40 2 16".times.68" -- Improved 40 4 16".times.68" 100. Conventional 40 1 16-3/16".times.49" 74.5 Conventional 40 5 16-3/16".times.49" 80.6 Conventional 40 10 16-3/16".times.49" 84.5 Conventional 40 15 16-3/16".times.49" 87.4 Conventional 50 1 16-3/16".times.49" 76.5 Conventional 50 5 16-3/16".times.49" 81. Conventional 50 10 16-3/16".times.49" 83.7 Conventional 50 15 16-3/16".times.49" 84.5 Improved 25 5 16-3/16".times.49" 100. Conventional 25 4 16-1/2".times.49" 72.3 Conventional 25 4 16-1/2".times.49" 66. Improved 25 2.2 16-1/2".times.49" 96. Improved 25 2.2 16-1/2".times." 93.8 Conventional 25 7.75 16".times.68-7/8" 53.7 Conventional 25 7.75 16".times.68-7/8" 54.5 Conventional 25 10.5 16".times.68-7/8" 55. Conventional 25 10.5 16".times.68-7/8" 54.4 Improved 25 3 16".times.68-7/8" 95. Improved 25 3 16".times.68-7/8" 94.8 Conventional 25 23.5 50".times.65-1/4" 62.2 Conventional 25 23.5 50".times.65-1/4" 58.8 Conventional 25 29.5 50".times.65-1/4" 50.6 Conventional 25 29.5 50".times.65-1/4" 54.4 Improved 25 8.9 50".times.65-1/4" 91. Improved 25 8.9 50".times.65-1/4" 93.2 __________________________________________________________________________

It will be evident from the foregoing that, for a given gas line pressure, the improved purging and filling process of this invention provides upwards of 85 - 100 percent by volume of chlorodifluoromethane gas in the space between the glass sheets, at least three to four times faster than was possible when purging and filling by the conventional method. In fact, using the improved purging and filling process of this invention, it was found that, at a gas line pressure of 25 p.s.i. or above, 90 percent concentration of gas within a unit was easily obtained with just 1.5 volume changes, an accomplishment not capable of being duplicated when purging and filling by the conventional method. Moreover, in practicing the improved process of this invention, gas chromatographic analysis of air samples taken in the environment surrounding the purging and filling operation will show that, as purging and filling proceeds towards 100 percent, the wastage or release of purging and filling gas to this environment is substantially less than when purging and filling by the conventional method. Thus, greater economy of operation is readily achieved pursuant to this invention.

Although the present invention has been described with particular reference to the specific details of certain embodiments thereof, it is not intended that such details shall be regarded as limitations upon the scope of the invention, except insofar as included in the accompanying claims. For example, it will be evident that, so long as the pore hole is located in an upper disposed region of the unit, the general disposition of the multiple glazed unit itself can vary or be varied from the vertical and horizontal dispositions shown to any angular disposition therebetween.

Claims

We claim:

1. A method for purging and filling a multiple glazed unit having a pair of glass sheets sealed together around their marginal edges to provide an air space between the sheets and a pore hole located in a marginal edge portion of the unit comprising supporting the unit with said pore hole located in an upper disposed region of the unit and injecting a fluorocarbon gas through said pore hole into said space while simultaneously displacing air from said space through said pore hole to the exterior of the unit.

2. The method according to claim 1 wherein said gas is injected into said space for a time and at a rate sufficient to produce a concentration of gas within said space of between 85 to 100 percent by volume of gas based on the volume of the air space.

3. The method according to claim 2 which further includes the step of controlling said time and rate of gas injection to produce said gas concentration with 1.5 volumes of gas based on the volume of the air space.

4. The method according to claim 1 wherein said unit is vertically disposed.

5. The method according to claim 1 wherein said unit is horizontally disposed.

6. The method according to claim 1 wherein said unit is disposed at an angle between a vertical and a horizontal disposition.