US 2584953 A
Description (OCR text may contain errors)
Feb. 5, 1952 SEALING ELEMENT VENTILATING MEANS FOR DRY SEAL GAS HOLDERS Filed Jan. 24, 1949 FIGB.
INvENToR; JOHN H. w/GG/Ns,
Patented Feb. 5, 1952 SEALING ELEMENT VENATIIIIITING MEANS f FOR DRY SEAL GAS HOLDERS John H; Wiggins, Chicago, Ill. Application Januay 24, 1949, serial No. 72,505
`4 Claims. (01.48-178) This invention relates to gas holders of the typethat comprises a flexible, curtain-like fabric element for sealing a reciprocating piston that co-acts With a stationary part ,of the casing to form a gas storage chamber of variable volume, and particularly dry seal gas holders of the kind that are equipped with a back-stop against which said sealing element is adapted to be pressed byl the gases in the storage chamber, during the normal functioning of the apparatus.
In gas holders of the type or kind above mentioned, the curtain-like sealing element is composed of long strips or large pieces of gas-,tight fabric joined together by seams produced. by
f lapping the edge portions of adjacent strips and connecting said lapped portions to each other by an adhesive. If certain kinds of gases are stored in such a gas holder, there is a possibility of the piston sealing element failingor becoming defective as a result of gas pemieating or penetrating the seams of the' piston sealing element` and remaining in contact with the adhesive of a seam ,for a period of time suicient to soften the adhesive and permit the lapped parts of the seam to separate or pull apart. An'example of a gas which might cause the sealing elementto fail, is benzol vapors stored in a gas holder Whose sealing element is composed of pieces 'of Thiokol rubber joined together by an adhesive consist-v ing of neoprene cement, and the reason Why gas that has penetrated or permeated a seam is liable to soften the adhesive of the seam, is that the abutment surface of the back-stop bears so tightly against the outer side or air side of the seam, that it traps the gas in the seam or connes the gas in the space between the abutment surface and the outer side of the seam, with the result that the gas remains in contact with or exerts a deleterious action on the adhesive, for a period of time great enough to soften the adhesive or cause the adhesive to become inactive or inoperative for the purpose for Whichit is employed.
The main object of my invention is to elemi` nate the possibility of the flexible, piston sealing element of a gas holder of the kind above 'described failing or becoming defective as a result of gas penetrating a seam of the sealing element and becoming trapped or conned in a position Where its action on the adhesive of the'seam will cause the adhesive to soften. To thisend I propose to construct the back-stop or abutpenetrated or permeated a seam of the sealing element from' remaining in contact with the cement or other adhesive used to join the lapped portionsnof said seam, the term cement" being herein used to cover any suitable kind of an adhesive for joining `or connecting together the piecesof fabric which constitute the piston sealing element. Brieiiy stated, I'attain' this highly desirable result by constructing a gas holder of the general type referred to', in such a Way that when the piston sealing element is co-acting With its back-stop or abutment surface, the major portion of the area of said sealing element will be thoroughly supported yagainst stresses or strains by a continuous or unbroken surface which stops permeation of gas through the sealing element, and any gas that penetrates or permeates the seams of' the sealing element will not be trappedor conned in a position' where said gas will have a deleterious action on the cement in said seams, but instead, said gas will be evaporated or carried away from the seams by air which contacts with or rcirculates over the outer sides of the seams. Various means may be used to attain circulation of ai'r'o'r presence of air between the air side of the sealing element and the back-stop, Without departing from the spirit of my invention. One eillcient and inexpensive Way to attain the above described result is to attach raised members to the abutmentV surface of the back-stop inproximity to the seams of the sealing element,` so that When the sealing element is p ressedvagainst the back-stop, said raised members will produce air spaces or pas! sagevvays between thezback-stop and the outside or air'side of the seam portions of the 'sealing element. Another Way'v is to provide they back` stop with air channels'or grooves disposed so that when the sealing element is in engagement with the back-stop, the outside or air side of the seams of the sealing element Will be in alignment with said air channels, and the air in said channels Will effectively ventilate the seams in the sealing element. A third Way consists in forming projections or protuberances on the outside surface of the sealing element adjacent the seams of the sealing elementy so that when the thus expose the outer side or air side of the ment surface of an apparatus of the general kind referred to so that it has the f olloWingcharacteristics or will accomplish the following results: A, it will thoroughly support the iiexible piston sealing element against stresses-ganci strains and insure that approximately %y of said sealing element Will lie against and be backed up by a solid surface that eifectively stops permeation of gas through said sealing element;
andB, it will effectively prevent gas that yhas seams in the sealing element to the action of air.
Figurel ofthe'drawings is a vertical, transverse sectional View of a piston-type, dry-seal gas holder constructed inaccordance with my invention. Figure 2 is an enlarged, fragmentary, horizontal sectional view, taken on the line 2 2 of Figure 1. Figure 3 is an enlarged, fragmentary, elevationalvievv, looking radially from the center of the top side of the piston and showing a portion of the sealing element and a portion of the back-stop on the piston.
Figure 4 is a vertical, longitudinal sectional view, illustrating another form of my invention, that comprises air channels formed'in the backstop in longitudinal alignment with the seams of the sealing element, the back-stop being formed by part of the upper portion of the side wall of the container, and said view being taken on the line 4-4 of Figure 5.
Figure 5 is a horizontal sectional view of the structure shown in Figure 4; and
A Figure 6 is a fragmentary. longitudinal sectional view, illustrating still another form of my invention, consistinguof protuberances or pro- Jections formed on the outside or air side of the sealing elementadjacent the seams orsaid element. Y
In Figure l of the drawings A and B designate, respectively, the piston and the stationary container ofthe stationary part of the apparatus that co-act with each other to form a gasstorage chamber of variable volume. The piston A is sealed by a sealing element C attached to the peripheral edge of the piston and to an intermediate portion of the side wall of the container B. The lower portion D of the container side wall is gas-tight and constitutes the side wall of :the gas storage chamber of the apparatus, and part of the upper portion of the `container side .wall serves as a back-stop D' for the piston sealing element C during the normal functioning of the apparatus. Inasmuch as said back-stop D- is constructed of metal plates, riveted or welded to each other, it forms a continuous, unbroken solid metal surface, which, when engaged by the sealing element C, thoroughly supports said sealing element against stresses and strains. Also, due vto the fact that said metal surfaceis impervious or non-porous, it effectively stops permeation of gas through .the fabric of which the piston sealing element C is constructed. In the gas holder herein illustrated the piston is also provided with a back-stop for thesealing element, formed by an annular member E that projects upwardly from the top side of the piston at the peripheral edge of the piston, said member E also being preferably constructed of metal plates so as to produce a supporting surface having the same characteristics as the backstop D'. When the piston A is-in-its lowermost position, as shown in broken lines in Figure l, the gases in the storage chamber of the apparatus exert pressure on the sealing element C ina direction to press a portion of said sealing element into snug engagement with the backstop E on the piston, and when the piston moves upwardly,l as shown in solid lines in Figure l-, the sealing element C is stripped off the backstop E on the piston and applied to the backstop D on the container side wall. Asis usual in gas holders equipped with a flexible, curtainlike "dry-seal C, said seal is composed of long strips or large pieces of gas-tight fabric whose adjacent edge portions are lapped and joined together by cement or any suitable kind of an adhesive, so as to produce cemented seams zr. as shown in Figure 2.`
As previously explained, if gas penetrates or I permeates through a seam ofthe fabric sealing element C, there is danger of said sealing element failing, if such gas is allowed to remain in contact with or in close proximity to the cement of the seam. long enough to cause the cement to soften and permit the lapped parts of the seam to separate or pull apart. In order to eliminate the possibility of this happening, I construct the apparatus in such a way that when the sealing element C is in engagement with either one or both of the back-stops D' or E. the seams n: in the portion or portions of the sealing elementcontacted by said back-stop or back-stops, will be effectively ventilated on the air side of said seams, with the result that any gas that has penetrated or permeated said seams will escape to the atmosphere, and accordingly, prevented from softening or having a deleterious action on the cement of the seams.
In the form of my invention shown in Figures l, 2 and 3, vertically-disposed members, usually consisting of straight rods or strips l, are attached to the outer side of the back-stop E on the piston in vertical alignment with the seams :c of the sealing element C, so that when a portion -of said sealing element is pressed against the back-stop E, as shown in Figure 2, air circulating channels or passageways y will be formed between the back-stop E and the outside or air side of the seams a' in the portion of thesealing element contacted by the back-stop E. Similar vertically disposed strips or rods la are also attached to the inner face of the portion of the tank side wall that constitutes the back-stop D', so that when a portion of the sealing element is in engagement with the back-stop D', the strips or longitudinally-disposed projections IEL on the back-stop D' will prevent the outer sides of the seams :z: in the said portion of the sealing element from snugly engaging or bearing against said back-stop D. Obviously, the above mentioned strips I and In should be made of such dimensionin .cross section that the portions of the piston sealing element between the seams :c will snugly engage the solid supporting surfaces of the back-stops. It will thus be seen that back-stops of the kind above described, in addition to forming solid or continuous supporting surfaces that back up the entire area of the portions of the piston sealing element engaged by same, also effectively ventilate the seams in portions of the sealing element C contacted by the back-stops, and prevent gas that has penetrated or seeped through such seams from being trapped or confined in a position where it is liable to soften the cement of the seams and cause the seams to fail. In order to insure an adequate supply of air to the air circulating channels or passageways y, I form small air holes or Ventilating ports e in the back-stop E preferably at intervals throughout the height of the strips I on said back-stop and in close proximity to said strips, and I also form similar small air ports z in the back-stop D', preferably at the lower end of the strips l, as shown in Figure l.
Instead of providing the back-stops of the apparatus with strips or equivalent raised devices l and I'L disposed in alignment with the seams of the sealing element C in such a way as to ventilate or aerate the air side of said seams during the time the back-stops are operating to absorb pressure exerted by the stored gases on the sealing element C, I can form air channels orcirculating passageways in the back-stops in longitudinal alignment with the seams a: of the sealing element C, as shown in Figures 4 and 5.' Said figures illustrate air channels or circulating passageways 2 formed in the side wall back-stop D by outwardly-projecting, channel-shaped portions 2a on the said back-stop.
In such a structure the outer side or air side of the seams :r in the sealing element C that are disposed in longitudinal alignment with the air circulating passageways 2 will be eiectively Ventilated by the air channels 2 in the way and for the purpose described. When a means of the kind shown in Figures 4 and 5 is used for ventilating the seams in the portion of the sealing element contacted by the back-stop E on the piston, said back-stop E is provided with channel-shaped portions 2a that project inwardly towards the center of the piston, thus forming air channels in the surface of the back-stop that is presented to the air side of the sealing element C.
In Figure 6 of the drawings I have illustrated still another inexpensive and efilcient means for Ventilating or supplying air to the air side of the seams of the sealing element C, consisting of protuberances 3 attached to the outer side or air side of the sealing element C along the length of the seams a: in said sealing element, and small Ventilating openings or air ports 3B formed in the back-stop at such points that when said protuberances 3 are in engagement with the back-stop, air will contact with or circulate over the air side of the seams in the piston sealing element, and the portions of said sealing element located between said seams will lie snugly against and be thoroughly supported by said imperforate portions of the backstops.
The drawings illustrate the sealing element C as being composed of longitudinally-disposed strips of fabric joined together by seams x that extend vertically of the back-stops when the sealing element is in engagement with the backstops. In the event the sealing element comprises seams that are disposed transversely of the sealing element and which extend horizontally of the back-stops when the sealing element is in engagement with the back-stops, such horizontally-disposed seams would be ventilated or supplied with air by means or devices `of the kind previously described, arranged so as to permit or cause air to circulate between the backstop and the air side of the seams in the portions of the sealing element contacted by the backstops.
In the claims I have used the rather cumbersome expression seams in the portion of the sealing element contacted by the back-stop to make it clear that my invention contemplates Ventilating the seams in the sealing element, only when said seams are arranged in such relationship with a back-stop, that the back-stop might trap or confine gas that has penetrated a seam and come in contact with the adhesive used to join the two lapped portions of the same. In any type or kind of gas holder provided with a seal formed by a curtain-like fabric element and equipped with a back-stop for said sealing element, there are periods in the cycle of operations of the apparatus, when portions of the sealing element do not press against the back-stop. For example, during the upward movement of the piston, the piston sealing element assumes the form of an upwardly-disposed loop, as shown in Figure 1, but there is no tendency for gas to concentrate in seams in the portion of the sealing element that is disposed in the form of a loop, due to the fact that the outside face or air side of said looped portion is presented to the air, and hence, any gas that might penetrate a seam of said looped portion, will evaporate or escape into the air instead of remaining in engagement 6 with the adhesive used in said seam. It is for this reason that I have used the expression previously quoted.
Having thus described my invention, what I claim as new and desire to secure by Letters Patent is:
1. A gas holder provided with a reciprocating piston and a stationary part that co-act with each other to form a gas storage chamber of variable volume, a sealing element for said piston formed from a plurality of pieces of gas-tight fabric joined together by cemented seams, a back-stop against which said sealing element is adapted to be pressed by the gases in the storage chamber, said back-stop having a solid surface that backs up the pieces of fabric located between the seams of said sealing element and stops permeation of gas through said fabric, and
devices located on the air side of said sealing element in longitudinal alignment with the seams in said element and disposed so as to hold at least a portion of the outside faces of said seams, out of contact with the back stop, whereby air can circulate over the outer side of said seams and carry away gas that has permeated or penetrated into said seams from the storage chamber.
2. A gas holder of the kind described in claim l, in which the devices that hold at least a portion of the outside faces of the seams of the sealing element out of contact with the backstop, consist of strips mounted stationarily on the back stop and projecting forwardly from the surface of same contacted by the sealing element, so as to lie between the back stop and the sealing element in the zones of the seams of the sealing element when said sealing element is pressed against the back stop.
3. A gas holder of the kind described in claim 1, in which the devices that hold at least a portion of the outside faces of the seams of the sealing element out of contact with the backstop, consist of protuberances on the air side of the sealing element, located at one side of each seam of said element and arranged in spaced relation along the length of the seams, said protuberances projecting beyond said seams so as to bear against the back stops and hold said seams spaced away from the back stop.
4. A gas holder of the kind described in claim 1, in which the devices that hold at least a portion of the outside faces of the seams of the sealing element out of contact with the back stop, consist of grooves in the surface of the back stop contacted by the sealing element. disposed so that when the sealing element is pressedagainst the back stop, the seams in said element lie in direct longitudinal alignment with said grooves and with the outside faces of said seams spaced away from the bottoms of said grooves.
JOHN H. WIGGINS.
REFERENCES CITED The following references are of record in the le of this patent:
UNITED STATES PATENTS Number Name Date 2,050,685 Wiggins Aug. 11, 1936 2,194,581 Weichsel Mar. 26, 1940 2,478,731 Wiggins Aug. 9, 1949 FOREIGN PATENTS Number Country Date 4,790 Great Britain of 1823