US3022717A - Closures for upright pipes or stacks - Google Patents

Description

Feb. 27, 1962 w. w. WEBSTER CLOSURES FOR UPRIGHT PIPES OR STACKS 2 Sheets-Sheet 1 Filed Aug. 8, 1958 Feb. 27, 1962 w. w. WEBSTER CLOSURES FOR UPRIGHT PIPES OR STACKS 2 Sheets-Sheet 2 Filed Aug. 8, 1958 nite States Patent 3,022,717 CLOSURES FOR UPRIGHT PIPES R STACKS William W. Webster, Lockport, N.Y.', assignor to General Motors Corporation, Detroit, Micln, a corporation of Delaware g Filed Aug. 8, 1958, Ser. No. 754,053

3 Claims. (Cl.98+-59) This invention relates to closures for exhaust or ventilation systems and more particularly to closures for controlling the outlets of upright or vertical pipes or stacks utilized in exhausting fluids such as gases.

In many industrial plants ditiiculties have been encountered in the control of systems from which air or gases must be discharged to the atmosphere. It is obviously desirable that such systems be protected from the weather at all times and regardless of plant operation or shutdown. It is also clear that many such systems should be protected from forceful admission of ambient air which could adversely afiectcertain operating procedures. Various forms of covers or closures for exhaust ducts have been employed in attempts to provide suitable protection, but such forms have heretofore been found unreliable or unsatisfactory for various reasons. In chemical plants particularly, corrosive gases caused previous closures to deteriorate and become disabled after short intervals of use. In many cases cross winds would render the effectiveness of the closures questionableas such winds wouldserve to make the closures operate erratically and often would disable them entirely.

An object of the present invention is to provide animproved closure for an upright stack, the closure being of simple structure avoiding close tolerances and thereby being operable under adverse conditions.

To this end, a feature of the present invention comprises an impervious closure member provided with armate guiding surfaces for slidably engaging the inside wall surface of an upright pipe or stack. Another feature comprises an impervious closure member of conical configuration. Another feature pertains to a closure member having an inclined wall or flat sides so inclined as to be adapted outwardly to deflect fluids or gases emanating from an exhaust system.

These and other important features of the invention will now be described in detail in the specification and then pointed out more particularly-in the appended claims.

In the drawings FIG. 1 is a view in elevation of the upper end of an upright exhaust stack with a closure mounted on the stack in its closed position, portions of the stack and closure being in sectionbetter to reveal the construction;

FIG. 2 is a view in elevation of the structure shown in FIG. 1 but with the closure in its fully open position and a small portion of the stack being removed;

FIG. 3 is a view in elevation of the structure shown in FIGS. 1 and 2, the closure being canted to an extreme degree to illustrate the principle of operation;

FIG. 4 is a sectional view looking in the direction of the arrows 44 in FIG. 1;

FIG. 5 is a view in elevation of a modified structure for a closure as mounted in its open position on an exhaust stack of rectangular proportions, portions of the stack and closure being in section better to illustrate the construction; and

FIG. 6 is a sectional view looking in the direction of arrows 66 in FIG. 5.

In FIGS. 1 to 4, inclusive, an upright stack or pipe is depicted at 10. This stack is adapted to be closed by an impervious member generally indicated at 12 which is of such area as to exceed the internal cross-sectional 3,22,? i 7 Patented Feb. 27, 1962 ice area of the stack. As seen in FIG. 1, the member 12 is of such sizethat its margin rests upon the annular top edge of the stack 10 when the closure is in its closed position.

The member 12 comprises a circular disc 14 to the periphery of which are joined four rectangular and radial pieces 16. These pieces reinforce the margin of the disc 14 and are drilled to admit the threaded ends of eye bolts 18. Each eye bolt 18 passes through the pieces with its eye directed downwardly and locked in position by means of a nut 20. To the underside of the disc 14 is attached a depending cone 22 the margin 24 of which is in the form of a flat annular flange welded as at 25 to the disc 14 to complete the impervious member 12. Extending downwardly from points on the underside of the conical member 22 and lying within theperimeter of the flange 24 are guiding means which, in the present instance, comprise four spaced and depending metal strips 26, each being of U-shaped transverse cross-section. The upper end of each metal strip 26 is welded as at 28 to the top margin of the cone 22. One strip is shown in section and two are shown in full in FIGURE 1. The strips curve outwardly and downwardly to conform loosely near their lower ends with the inside wall vof the stack. The bottom end of each strip is joined as by welding 30 to the outer end of a radial arm 32, and the inner end of the latter is joined as at 34 to the cone near the apex thereof FIGURE 4 shows the manner of attachment of the strips 26 to the arms 32 to form alrigid structure. Spaced from the top edge of the stack 10 and on the exterior wall surface of the latter are four angle pieces 36 which are drilled as at 38 to receive cables 40. The upper end of each cable 40 is fixed to the eye of a bolt 18 and the cable extends down through the drilled opening in an angle plate 36 and hangs freely to suspend a weight 42 at its bottom end.

In the operation of the conical closure, if the exhaust system served by the stack 16 is closed down, it is clear that the closure will drop down by dead weight and seat on the end of the stack as shown in FIG. 1. The weights 4?. are not essential but are preferred in some instances as they serve as additional means insuring definite closure of the stack in the absence of predetermined gas pressure within the latter and also as stops limiting the extent of movement of the closure. 7

When the system is in operation and adequate gas pressure exists in theustack 10 and must be discharged to atmosphere, thepressure of that gas will cause the closure to lift into itsfully. open position as shown in FIG. 2. The weights 42Hthen1serve as stop means, as stated above, limiting the extent to..whichthe closure may be moved upwardly. It is obvious that these weights may also be chosen to limit the amount of gas discharged with a given pressure; i.e., it is not essential in practicing the present invention that the closure be open to its fullest extent. Also, the weights may be varied to suit the circumstances.

In actual practice the closure of FIGS. 1 and 2 will not be adversely influenced by cross winds, but in the event some freakish occasion may cause a canting of the closure as depicted in FIG. 3, the arcuate contours or outwardly facing surfaces 29 of the strips 26 are such that no monkey grip effect is experienced between those strips and the inside wall of the stack. This is graphically illustrated in FIG. 3 in which figure it may be seen that there is nothing preventing the closure from operating and moving up or down even though the closure may be canted to an extreme angle. The canting to such an angle because of cross winds is possible but highly improbable. In the event the Strips 26 or the stack 10 become corroded or encrusted with foreign materials, the closure will not be prevented from operating despite extreme canting because 3 of the absence of close tolerances between the surfaces 29 and the stack 10.

FIGS. 5 and 6 illustrate a modification of the closure structure. From these figures itmay 'be seen that the closure need not be conical or have any specific configuration. In these figures the impervious member is generally depicted at 50 to include a rectangular top plate 52 the linear margins of which are adapted to engage the top edge of a rectangular stack 54 when the closure is in its at rest position for closing the stack. Six pieces 56 are shown reinforcing the margins of the plate 50 at localized and spaced areas for the reception of eye bolts 18 similar to those used in the embodiment of FIGS. 1 and 2. Angle pieces 36 together with cables 40 and weights 42 are used in associating the closure 50 with the stack 54 in a manner similar to that depicted in FIGS. 1-4. Affixed to the bottom surface of the rectangular plate 50 is attached the margins of a somewhat pyramidal form having inclined flat sides and diminishing in periphery as it extends downwardly into the stack. Arcuate strips 58 are employed in a capacity similar to that of the strips 26. These are fastened at their upper ends by welding to the flat walls and at their lower ends to horizontal bars 69 which in turn are joined to the fiat Walls near the apex of the pyramidal form. The strips 58 extend arcuately from the plate 52 in such a way as slidably to clear the inside wall of the stack 54. In this modification it is demonstrated that no monkey grip effect may take place to jam the device in a partially or fully open position even though the cross section of the stack or pipe be changed to a rectilinear form.

From the above, it may be seen that the invention resides in a device which is automatic in its operation, that its motivation is by dead weight in the interest of simplicity, that the device is directionally stabilized, nonfrictional and is not subject to vibration as it protects an exhaust system against back draft and outside weather elements. Blower operation in a system served by the stack will cause the closure to rise to a controlled height and the closure will, automatically seat on the stack rim when the system is closed down. The cables 40 may be rods, chains or some other type of equivalent flexible connections. The flexibility of these connections prevents the transmission of vibration from the stack to the closure. The closure will not offer rigid resistance to cross winds and, therefore, it need not be constructed heavily and will maintain its position satisfactorily whether it be closed or open.

I claim:

1. A closure in combination with the upper end of a vertical ventilation duct, said closure comprising an impervious member having a deflecting surface and a peripheral flange, said flange being arranged to seat on the said end of said duct with the said surface extending into said duct, multiple guiding means attached to said member within the confines of said flange with their upper ends in a normally horizontal plane, and said guiding means presenting curved contours each arcuately extending in a normally vertical plane and bulging outwardly from said impervious member and toward and clearing the interior wall of said duct for loose guidance by said wall during vertical movement of said closure with relation to said duct.

2. A closure in combination with the upper end of a ventilation duct, said closure comprising an impervious member having a deflecting surface and a peripheral flange, said flange being arranged to seat on the said end of said duct with the said surface extending into said duct, vertically extending rigid guiding means with upper ends attached to said member and their lengths presenting outwardly curved contours facing the interior wall of said duct and being normally clear of the latter for loose guidance of the closure, horizontal arms connecting the lower ends of said guiding means to said member to lend rigidity to said guiding means, and flexible stop means fixed to the said closure and adapted to limit the extent of vertical motion of the latter with respect to said duct.

3. A closure in combination with a vertically extending ventilation duct having an upwardly directed open end, said closure comprising an impervious member of larger area than the cross-sectional area of said duct, said impervious member being positioned to register with and to seat on said open end, vertically extending guiding means fixed to the underside of said impervious member and extending into said open end, surfaces on said guiding means presenting outwardly bowed contours and having dimensional stability retaining a clearance space between said guiding means and the inner wall surface of said duct, and the arrangement being such that said closure is loosely restrained by said duct in any horizontal direction and movable in a vertical direction and 'titltable by gas pressure developed within said duet.

References Cited in the file of this patent UNITED STATES PATENTS 141,309 Barnes July 29, 1873 245,904 Wiley Aug. 16, 1881 322,832 Kjttoe July 21, 1885 360,781 ,Nye Apr. 5, 1887 401,678 Baines Apr. 16, 1889 715,169 Stanley Dec. 2, 1902 1,204,702 Schupp Nov. 14, 1916 2,337,382 Frankland Dec. 21, 1943 2,368,320 Norris Jan. 30, 1945 FOREIGN PATENTS 730,511 France May 10, 1932

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