Abstract:
Improved, non-fragmenting, high efficiency vent apparatus ( 10, 78 ) are provided for protecting a structure ( 12 ) from potentially damaging or destructive abnormal pressure conditions. The apparatus ( 10, 78 ) is positioned in covering relationship to a vent opening ( 14 ) formed in the structure ( 12 ), and generally includes a burst member ( 16 ) and a tab assembly ( 18 ) equipped with a series of tabs ( 56 ); the tabs ( 56 ) bend or buckle to a burst member-clearing position when the vent apparatus ( 10, 78 ) experiences an abnormal pressure condition, thereby permitting rapid opening of a central section of the burst member ( 16 ) to thus protect structure ( 12 ). The burst member ( 16 ) may be of domed or flat construction, and can be in the form of a quadrate panel or any other desired shape.

Description:
BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present invention is broadly concerned with vent apparatus of the type used to protect structures (e.g., bag houses, bins, and tanks) from the potentially destructive effects of abnormal pressure conditions therein, i.e., either excessively high or low pressures which could lead to catastrophic failure of the structure. More particularly, the invention is concerned with such vent apparatus having a rupturable burst member normally retained in place by means of a plurality of spaced apart, bendable, non-fragmenting tabs; in the event of an abnormal pressure condition, the tabs bend or buckle without breakage thereof to a member-clearing position allowing the burst member to quickly open to thus vent and protect the structure. The vent tabs are preferably designed as simple, low-mass, torque and load insensitive components which are advantageously out of contact with the protected area within the structure, and provide increased venting efficiency without any rupture or fragmentation of the tabs. 
     2. Description of the Prior Art 
     A wide variety of protective devices have been employed in the past to protect confined areas or zones, such as in buildings, manufacturing facilities, tanks, chambers, and other structures. These devices are intended to quickly terminate or interrupt potentially destructive phenomena, such as high pressure conditions conducive to explosions or fires. Generally speaking, venting assemblies are used in this context which include a rupturable member such as a rupture disc or burst panel. Such components are responsive to pressure conditions within a structure to be protected, and are designed to open and vent the structure in the event of an abnormal pressure condition. In some cases, these burst discs or panels fragment upon actuation thereof, but in other instances venting occurs with retention of the disc or panel. 
     U.S. Pat. No. 5,606,829 describes a mounting assembly for a decompression panel used in aircraft and having blow-out tabs arranged in pairs around the margin of the panel. 
     The tabs are designed to break in the even of an over- or under-pressure condition, which serves to release the panel. 
     U.S. Patent Publication 2011/0017315 describes a pressure relief panel for a silo or dust collector having a line of weakness along the panel perimeter, which may be a series of slits that form tabs. The number of slits/tabs controls the pressure differential at which the panel will open. 
     U.S. Pat. No. 4,385,710 is directed to an emergency pressure relief device for an oil-reserve tank or the like, having a flexible plate secured to a coaming with welds intervals, and flexible sealant between the welds. The length and strength of the welds determines the burst pressure. 
     U.S. Pat. No. 5,036,632 is directed to a pressure relief panel assembly for tanks, food-processing vessels, and bag houses, having a rupture panel with a hinged blow-out part  22  connected to a restrained part via a plurality of rupture tabs with slits there between. The thickness of the material of the panel and the length of the slits determines the burst pressure. 
     Other references include U.S. Pat. Nos. 4,385,710, 5,461,831, 5,638,980, 6,367,203, and 7,628,167. 
     The above-described prior art references do not teach or suggest provision of a vent apparatus with a burst member normally maintained in place by means of non-fragmenting bendable tabs which move to a member-clearing position when the burst member experiences an abnormal pressure condition. 
     SUMMARY OF THE INVENTION 
     The present invention provides improved, non-fragmenting vent assemblies for protecting a variety of structures subject to abnormal pressure conditions. Generally speaking, the vent apparatus of the invention includes a burst member presenting an outer margin and a tab assembly including a plurality of spaced apart, non-frangible tabs in proximal relationship to the burst member outer margin. Mounting structure is provided to operably mount the burst member and tab assembly adjacent a vent opening in an area or structure to be protected. The tabs are configured and oriented to overlie the burst member outer margin in the unopened condition thereof when the burst member experiences only normal pressure conditions. The tabs at least partially serve to maintain the burst member in its closed position under normal pressures. In the event of an abnormal pressure condition, such as one which could damage the protected structure, the tabs are operable to bend or buckle to a member-clearing position without fragmentation of the tabs, to thereby permit the burst member to rapidly open to relieve the abnormal pressure condition. 
     In preferred forms, the burst member may be of flat or domed construction, and can be any desired shape, such as quadrate or round. The burst member margin is advantageously configured with a line of opening throughout at least a portion thereof, with the tabs adjacent and overlying the line of opening, in order to establish the desired normal maintenance of the burst member in its closed position. A seal is provided to prevent egress of fluid (e.g., gas or liquid), from the protected structure through the line of opening. 
     The mounting structure for the burst member/tab assembly preferably comprises upper and lower open frames with the burst member and tab assembly there between, along with threaded fasteners for maintaining the entire vent apparatus in place. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a perspective view of a complete vent apparatus in accordance with one embodiment of the invention, mounted on a structure to be protected; 
         FIG. 2  is a perspective assembly view of the vent apparatus illustrated in  FIG. 1 ; 
         FIG. 3  is an enlarged, fragmentary view, with parts broken away, illustrating a vent tab plate adjacent the burst member of the assembly of  FIGS. 1-2 , with the vent tabs of the plate maintaining the burst member in its unopened position; 
         FIG. 4  is an enlarged, fragmentary view of a corner of the burst member, illustrating the hinge section thereof; 
         FIG. 5  is an enlarged, vertical sectional view of the vent apparatus depicted in  FIGS. 1-2 , with the burst panel in its unopened condition; 
         FIG. 6  is an enlarged, fragmentary, sectional view illustrating the burst member of the vent apparatus during opening thereof, with the vent tabs being bent to a member-clearing position; 
         FIG. 7  is a fragmentary, perspective view, with parts broken away, further illustrating the burst member during opening thereof; 
         FIG. 8  is an enlarged, vertical sectional view of a vent apparatus in accordance with another embodiment of the invention, including a modified sealing arrangement; and 
         FIG. 9  is a perspective assembly view of the vent apparatus illustrated in  FIG. 8 . 
     
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
     Turning now to the drawings, a vent apparatus  10  in accordance with the invention is illustrated in  FIG. 1 , appropriately mounted on a structure  12  to be protected. The structure  12  has a vent opening  14  of predetermined configuration and size, and the apparatus  12  is in normal covering relationship to the opening  14 . As explained hereinafter, the apparatus  10  is designed to quickly open in the event of an abnormal (e.g., excessively high or excessively low) pressure within structure  12 , in order to vent the structure and prevent damage to or destruction thereof. The apparatus  10  broadly includes a burst member  16 , a tab assembly  18 , and mounting structure  20  serving to operatively mount the burst member  16  and tab assembly  18  relative to vent opening  14 . Generally, the components of the apparatus  10  are of metallic, open-frame design; in stacked, face-to-face relationship with each other; in surrounding relationship to vent opening  14 ; and secured to structure  12  by suitable connectors. All of the components have a peripheral open frame design save for burst member  16  which covers the opening  14 . 
     In more detail, the burst member  16  in the illustrated embodiment is in the form of a generally quadrate metallic burst panel  22  having a central domed burst section  24  and a continuous, essentially flat peripheral margin  26 . A continuous transition region  28  provides a demarcation between the section  24  and margin  26 . Referring to  FIG. 2 , it will be seen that the panel margin  26  includes opposed front and rear sections  30  and  32 , as well as opposed side sections  34  and  36 . A line of opening  38  extending completely through the thickness of margin  26  extends from the corner between sections  30  and  34 , throughout the lengths of sections  34 ,  32 , and  36 , and terminates at the corner between sections  30  and  36 . In alternate embodiments, the line of opening  38  may extend only partially through the thickness of margin  26 , as opposed to an entirely through cut. Further, line of opening  38  may also be discontinuous comprising, for example, a series of spaced apart cuts or slits. A non-cut hinge region  40  extends between the opposed ends of the line of opening, along the length of front section  30 . Additionally, a series of mounting apertures  42  are provided around the entire margin  26 . The burst member  16  is advantageously formed of a metal, such as stainless steel, and has an appropriate thickness and other properties, depending upon the desired rated burst capacity. 
     The tab assembly  18  is in the form of a tab frame  44  which abuts burst member  16 . To this end, the tab frame  44  has opposed front and rear sections  46 ,  48 , and side sections  50 ,  52  designed to overlie the sections  32 - 36  of burst member  16 . The frame sections  46 - 52  are also provided with mounting apertures  54  which are in registry with the apertures  42 . The inner margin of tab frame  44  has a series of integral, spaced apart, inwardly extending, non-frangible tabs  56  with gently arcuate inner surfaces  56   a  which overlie the line of opening  38 , but are just short of the transition region  28  ( FIGS. 3 and 5 ). It is understood, however, that tabs  56  may comprise other shapes and configurations, such as quadrate or trapezoidal, which may include rounded corners to prevent puncturing burst member  16  upon opening thereof. 
     The mounting structure  20  includes a bottom frame  58 , which is secured to the structure  12  in surrounding and overlying relationship to vent opening  14 . The frame  58  includes a plurality of threaded connector bores  60 . The mounting structure  20  further includes a seal frame  62  with mounting apertures  64  and presenting an inner margin  66 . The seal frame  62  rests directly atop the bottom frame  58 . A continuous gasket seal  68  is situated within the confines of seal frame  62  along the inner margin  66  thereof. As best seen in  FIG. 5 , the seal  68  is partially supported by bottom frame  58 , extends inwardly therefrom, and is in covering relationship to line of opening  38 . A top frame  70 , having mounting apertures  72 , is positioned over the tab frame  44  and has an inner periphery  74  along the bases of the tabs  56  and directly adjacent the line of opening  38  (see  FIG. 5 ). Bottom frame  58  also extends inwardly of inner margin  66  and inner periphery  74  so as to provide a support for burst panel  22 , and especially line of opening  38 , and thereby offering resistance to inward shifting of the burst panel should the protected structure  12  be subject to vacuum conditions or normal cycling of pressures within the protected structure. The mounting structure  20  further has a plurality of screws  76 , which extend through the mounting apertures  72 ,  54 ,  42 , and  64  and are received within the bores  60 . 
     During normal use of structure  12  when no abnormal pressure conditions exist, the vent assembly  10  is static and the burst panel  22  remains intact in blocking relationship to the vent opening  14  formed in the protected structure  12 . In this condition, flow of fluid (e.g., gas) from the protected structure  12  through line of opening  38  is prevented by the presence of gasket seal  68 . Furthermore, the presence of the tabs  56  serves to at least partially maintain the dome section  24  of burst panel  22  in its closed position. Preferably, the tabs  56  constitute the sole means of maintaining the burst panel  22  in the closed position thereof. 
     However, in the event of an abnormal pressure condition, the dome section  24  of burst panel  22  opens to vent the structure  12 . This opening occurs along the length of line of opening  38 , with the hinge region  40  serving to prevent the dome section  24  from entirely separating from the vent apparatus  10 . Furthermore, as the dome section  24  opens, the inwardly extending tabs  56  bend or buckle outwardly about the inner periphery  74  of top frame  70  (see  FIGS. 6 and 7 ), to an upright orientation, as opposed to being substantially co-planar with the rest of tab frame  44 . This creates a clearance between the tabs  56  and the line of opening edge of dome section  24 , thus allowing rapid opening of the dome section  24 . It will be observed that this opening action occurs without any breakage or fragmentation of the tabs  56  along the length of line of opening  38 . In addition, the tabs  56  along the length of the hinge region  40  also bend upwardly as necessary to accommodate movement of the dome section  24 . It will be appreciated that tabs  56  along the hinge region  40  are not essential to the operation of vent apparatus  10 . However, their presence is preferred so as to facilitate manufacture of the tab frame  44  and to absorb some of the energy generated as a result of opening of the dome section  24  to prevent failure of the hinge region and fragmentation of the panel  22 . 
       FIGS. 8-9  depict another vent apparatus  78 . The apparatus  78  is very similar to apparatus  10  and the components of apparatus  78  identical to those of apparatus  10  are identically numbered. The apparatus  78  differs from apparatus  10  in a number of respects. First, the apparatus  78  has a support plate  80  having mounting apertures  82 , positioned over base frame  58 ; and a spacer frame  84  having mounting apertures  86  overlying the support plate  80 . The spacer frame  84  is equipped with a modified gasket seal  88  having a continuous, hollow, innermost bead  90  (e.g., a “P” seal). It will be seen that the gasket  88  terminates at the edge of base frame  58  and support plate  80 , and does not extend into opening vent opening  14 . The screws  76  extend through the registered mounting openings  72 ,  54 ,  42 ,  86 , and  82 , and are received within the bores  60  of base frame  58 . Spacer frame  84  prevents overcompression of gasket seal  88  during assembly of apparatus  78 . The design of  FIGS. 8-9  provides a more robust seal, as compared with the design of  FIGS. 1-7 . The operation of vent apparatus  78  is identical to that of apparatus  10 , and thus need not be further described. 
     The vent apparatus of the invention provides a number of desirable features. The design provides a single element explosion vent with the complete elimination of rupture tabs. As such, the rated burst condition for the vent apparatus hereof is not dependent upon the material thickness of the burst panel, but rather the deformation or bending characteristics of the tabs  56 . Furthermore, the tabs  56  are not in contact with the vent opening  14 , so that temperature and/or corrosive conditions within the protected structure  12  do not significantly alter the operation of the vent assembly. The vent tab design is inherently simple and is insensitive to both torque and load. While the vent apparatus hereof is more usually used in the context of protecting against abnormally high pressures, it can equally be employed in a low pressure or vacuum condition context.