Patent Publication Number: US-2022220803-A1

Title: Roll-Up Doors and Method for Securing Same

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     This application claims the benefit of U.S. Provisional Patent Application No. 62/278,202 filed Jan. 13, 2016 entitled “Roll-Up Doors and Method for Securing Same”, which is incorporated by reference herein in its entirety. 
    
    
     FIELD OF THE INVENTION 
     The present invention, according to some embodiments, relates to roll-up doors. More particularly, in some embodiments the present invention relates to roll-up doors having one or more retention bands configured to secure the roll-up door to a guide. In further embodiments, the present invention relates to methods for securing a roll-up door to a guide. 
     BACKGROUND OF THE INVENTION 
     Roll-up doors are often used to form a closure over an opening in a building, such as garages, warehouses, stores, etc. Such roll-up doors generally include a flexible curtain which can be coiled and uncoiled from a shaft that is mounted at one end of the opening in order to open and close the opening. To close the opening, for example, the flexible curtain may be uncoiled from the shaft such that an end of the flexible curtain is extended away from the shaft toward an opposite end of the opening. Retracting the end of the flexible curtain toward the shaft by coiling the flexible curtain around the shaft uncovers the opening to allow access through the opening. For vertical doors, for example, the shaft may be mounted above the opening and the end of the flexible curtain may be lowered toward the floor to close the opening or raised to uncover the opening. 
     The side edges of the flexible curtains have been threaded into guides mounted along the lateral sides of the opening. Such guides are generally adapted to direct the flexible curtain as the flexible curtain is coiled and uncoiled and to help seal the sides of the opening. A difficulty that may be encountered with typical roll-up doors is that the side edges of the flexible curtain can be pulled out of the guides during operation or, for example, when a force is applied against the flexible curtain in the closed position. When this occurs, the roll-up door is unable to provide proper closure of the opening. 
     SUMMARY OF THE INVENTION 
     The present invention, according to some embodiments, provides a means and method for securing a flexible curtain of a roll-up door to a guide in order to prevent an edge of the flexible curtain from being pulled out of the guide. In some embodiments the present invention relates to roll-up doors having one or more retention bands configured to secure the roll-up door to the guide. 
     A roll-up door according to some embodiments of the present invention includes a flexible curtain including a front surface, a back surface, a first end coupled to a shaft, a second end opposite the first end, and first and second side edges extending between the first end and the second end, the flexible curtain being moveable between a retracted position wherein the flexible curtain is coiled around the shaft and a deployed position wherein the flexible curtain is uncoiled from the shaft. In some embodiments, a first retention band is mounted along at least a portion of the first side edge of the flexible curtain, the first retention band including an inner surface at least partially facing towards the flexible curtain, an outer surface opposite the inner surface, a fixed edge attached to the flexible curtain generally parallel to the first side edge, and a free edge opposite the fixed edge and movable relative to the fixed edge. 
     In some embodiments, the free edge of the first retention band is capable of deflecting toward or away from the flexible curtain. In some embodiments, the inner surface of the first retention band includes a convexly curved contour extending between the fixed edge and the free edge when the flexible curtain is in the deployed position. In further embodiments, the outer surface of the first retention band includes a concavely curved contour extending between the fixed edge and the free edge when the flexible curtain is in the deployed position. 
     In certain embodiments, at least a portion of the first retention band is configured to transition from a curved configuration to a flattened configuration when the flexible curtain moves from the deployed position to the retracted position, and at least a portion of the first retention band is configured to transition from the flattened configuration to the curved configuration when the flexible curtain moves from the retracted position to the deployed position. In some embodiments, in the flattened configuration, at least a portion of the inner surface of the first retention band is positioned against the flexible curtain. 
     In some embodiments, the flexible curtain includes a first reinforcement band at the first side edge, and the fixed edge of the first retention band is attached to the first reinforcement band. In some embodiments, the first reinforcement band is a metal band. In some embodiments, the fixed edge of the first retention band is substantially aligned with the first side edge of the flexible curtain. In some embodiments, the first retention band includes a single continuous component. In one embodiment, such a single continuous component reduces or eliminates edges that would result in snags as the roll-up door is operated. The single continuous component embodiment may also enhance the sealing properties of the roll-up door. In other embodiments, the first retention band includes a plurality of segments spaced along a length of the first side edge. In some embodiments, the first retention band includes a tapered end proximate the second end of the flexible curtain. 
     In certain embodiments, the first retention band is made of an elastic material, for example, steel (e.g., spring steel), aluminum, or other elastic metal or metal alloy. In other embodiments, the first retention band may be made from plastics or rubbers. In one embodiment, the first retention band is constructed from material that is elastic enough to retain a curved shape after being held in the flatted position for an extended period duration while still being thin enough to coil and strong enough to provide retention. In some embodiments, the roll-up door may be configured to contain fire and/or smoke. According to some such embodiments, the roll-up door is configured to withstand temperatures of 400° F. or greater, preferably 1800° F. or greater. Thus, in some embodiments, components of the roll-up door are made from materials configured to be retain strength at these temperatures, and may be made from fire-resistant or flame retardant materials. 
     A roll-up door according to some embodiments of the present invention further includes a second retention band mounted along the second side edge of the flexible curtain. In some embodiments, the second retention band may have any of the characteristics and properties described above and herein with respect to the first retention band. In some embodiments, for example, the second retention band includes an inner surface at least partially facing towards the flexible curtain, an outer surface opposite the inner surface, a fixed edge attached to the flexible curtain generally parallel to the second side edge, and a free edge opposite the fixed edge and movable relative to the fixed edge. In some embodiments, the second retention band may be symmetrically arranged with the first retention band. 
     Further embodiments of the present invention relate to a roll-up door assembly. In some embodiments, the roll-up door assembly includes a roll-up door as described above and herein in combination with a first guide. The first guide, according to some embodiments, defines a track configured and dimensioned to receive at least a portion of the first side edge of the flexible curtain. In some embodiments, the first retention band is configured to be received in the track defined by the first guide. In some embodiments, the first retention band is configured to anchor the first side edge of the flexible curtain within the track defined by the first guide. In some embodiments, the first guide includes a throat through which the first side edge of the flexible curtain is configured to be inserted, and the throat has an opening width that is less than a distance between the free edge of the first retention band and the flexible curtain when the flexible curtain is in the deployed position. In some embodiments, the first retention band is configured to deflect towards the flexible curtain in response to the first side edge of the flexible curtain being inserted into the throat. In some embodiments, a portion of the first guide is configured to be received between the inner surface of the first retention band and the flexible curtain. In one embodiment, the first guide includes a first element and a second element configured to engage the first element. In one embodiment, the throat is positioned between the first element and the second element. 
     In certain embodiments, the roll-up door assembly includes a second guide defining a track receiving at least a portion of the second side edge of the flexible curtain. According to some of these embodiments, the roll-up door includes a second retention band mounted along the second side edge of the flexible curtain, the second retention band including an inner surface at least partially facing towards the flexible curtain, an outer surface opposite the inner surface, a fixed edge attached to the flexible curtain generally parallel to the second side edge, and a free edge opposite the fixed edge and movable relative to the fixed edge. The second retention band, in some embodiments, is received in the track defined by the second guide and configured to anchor the second side edge of the flexible curtain within the track defined by the second guide. The second guide may have any of the characteristics described above and herein with respect to the first guide. Moreover, in some embodiments, the second guide may be symmetrically arranged with the first guide. In some embodiments, at least a portion of the inner surface of the first retention band may be adjacent the flexible curtain. In one embodiment, at least a portion of the outer surface of the first retention band may be adjacent the flexible curtain. 
     In yet a further embodiment, the present invention provides a method of securing a roll-up door to a guide. In some embodiments, the method includes providing a roll-up door comprising flexible curtain having a side edge and a retention band mounted along at least a portion of the side edge of the flexible curtain, the retention band including a fixed edge attached to the flexible curtain generally parallel to the side edge, and a free edge opposite the fixed edge and movable relative to the fixed edge, the retention band being capable of moving (e.g., bending) toward or away from the flexible curtain, providing a guide comprising a throat and a track configured to receive at least a portion of the side edge of the flexible curtain and the retention band, the throat having an opening width smaller than a width of the track, urging (e.g., bending) the retention band towards the flexible curtain by passing the side edge and the retention band through the throat and into the track of the guide, and allowing the retention band to move (e.g., bend) away from flexible curtain when the retention band and the side edge are received in the track of the guide. In some embodiments of the method, allowing the retention band to move (e.g., bend) away from flexible curtain increases a distance between the free edge of the retention band and the flexible curtain to above the opening width of the throat. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The foregoing summary, as well as the following detailed description of the invention, will be better understood when read in conjunction with the appended drawings. For the purpose of illustrating the invention, there are shown in the drawings embodiments which are presently preferred. It should be understood, however, that the invention can be embodied in different forms and thus should not be construed as being limited to the embodiments set forth herein. For example, although not expressly stated herein, features of one or more various disclosed embodiments may incorporated into other of the disclosed embodiments. The appended drawings may not be drawn to scale. 
         FIG. 1  is a generalized diagram showing a roll-up door assembly in a deployed position according to an embodiment of the present invention; 
         FIG. 2  is a generalized diagram showing the roll-up door assembly of  FIG. 1  shown in a partially retracted position; 
         FIG. 3  is a partial elevational view of a roll-up door according to an embodiment of the present invention; 
         FIG. 4  is a partial elevational view showing a detail of a roll-up door assembly according to an embodiment of the present invention; 
         FIG. 5  is a first partial perspective view showing a portion of a flexible curtain having a retention band in accordance with an embodiment of the present invention; 
         FIG. 6  is a second partial perspective view of the portion of the flexible curtain and retention band shown in  FIG. 5 ; 
         FIGS. 7A-7C  are cross-sectional views showing the changes in profile of the retention band of  FIG. 5  being flattened; 
         FIG. 8  is a partial perspective view showing a flexible curtain having a retention band that is partially wound around a shaft in accordance with an embodiment of the present invention; 
         FIG. 9  is a partial perspective view showing a flexible curtain having a retention band that is partially wound around a shaft in accordance with a further embodiment of the present invention; 
         FIG. 10  is a cross-sectional view showing a retention band inserted into a guide in accordance with an embodiment of the present invention; 
         FIG. 11  is a partial top perspective, cross-sectional view showing the position of a guide relative to a frame in accordance with an embodiment of the present invention; 
         FIG. 12  is a partial perspective view showing a flexible curtain having a segmented retention band in accordance with an embodiment of the present invention; 
         FIGS. 13A and 13B  are cross-sectional views showing profiles of alternative retention bands in accordance with embodiments of the present invention; 
         FIG. 14A , is a cross-sectional view showing a profile of an alternative attachment of the flexible curtain to the retention band in accordance with one embodiment of the present invention; 
         FIG. 14B  is a close up cross-sectional view of the flexible curtain and retention band of  FIG. 14A ; 
         FIG. 14C  is a close up cross-sectional view of the flexible curtain and retention band of  FIG. 14A ; 
         FIG. 15  in an exploded, top perspective view of the guide of  FIG. 10 ; 
         FIG. 16  is an assembled, top perspective view of the guide of  FIG. 15 ; 
         FIG. 17  is a front view of the flexible curtain of  FIG. 1  with decals; 
         FIG. 18  is a rear view of the flexible curtain of  FIG. 17 ; 
         FIG. 19  is a top perspective, sectional view of a guide in accordance with one embodiment of the present invention; and 
         FIG. 20  is an environmental view showing the flexible curtain of  FIG. 17  in an extended position. 
     
    
    
     DETAILED DESCRIPTION 
     The present subject matter will now be described more fully hereinafter with reference to the accompanying Figures, in which representative embodiments are shown. The present subject matter can, however, be embodied in different forms and should not be construed as limited to the embodiments set forth herein. Rather, these embodiments are provided to describe and enable one of skill in the art. All publications, patent applications, patents, and other references mentioned herein are incorporated by reference in their entirety. 
     Referring to the drawings in detail, wherein like reference numerals indicate like elements throughout, there is shown in  FIGS. 1-20  roll-up doors in accordance with exemplary embodiments of the present invention. 
       FIG. 1  shows generally a roll-up door assembly  100  in a deployed condition in accordance with certain embodiments of the present invention which, for example, may be used to cover an opening  20  in a wall  10  of a building or structure. Opening  20  may be, for example, a doorway to a garage, warehouse, store, etc., according to some embodiments. In some embodiments, opening  20  may be an opening for an elevator, for example, roll-up door assembly  100  may be used to cover an elevator door. In other embodiments, opening  20  may be a window. Roll-up door assembly  100  in some embodiments includes a flexible curtain  110  that is sized and shaped to cover opening  20  when in a deployed state. Preferably the area of flexible curtain  110  is larger than the area of opening  20 . While opening  20  is generally illustrated as a vertical opening, it should be appreciated that roll-up door assembly  100  may also be adapted to cover any openings, e.g., horizontal openings on the floor or ceiling of a building or structure. 
     Flexible curtain  110  may be made of any suitable flexible sheet material known in the art, for example, metal (e.g., steel, aluminum, corrugated metal), plastic sheets, rubber etc., and is configured to be wound and unwound from a shaft  120 . Flexible curtain  110  may have any suitable thickness to allow it to coil smoothly around shaft  120 . In some embodiments, for example, flexible curtain  110  has a thickness ranging from about 0.001 inches to about 0.1 inches. In some embodiments, flexible curtain  110  has a thickness ranging from about 0.002 inches to about 0.05 inches. Other thicknesses for flexible curtain  110  may also be used depending on the particular material selected. Shaft  120 , according to the some embodiments, is configured to be positioned at or proximate one end of opening  20 , and may take the form of an axle, rod, drum, etc. Shaft  120  may have any suitable diameter. In some embodiments, shaft  120  may have a diameter, for example, ranging from about 2 inches to about 6 inches, about 3 inches to about 5 inches, about 3.5 inches to about 4.5 inches. In some embodiments, shaft  120  has a diameter of at least 2 inches, at least 3 inches, at least 4 inches, at least 5 inches, or at least 6 inches. In some embodiments, a larger diameter shaft may help flexible curtain  110  to coil more smoothly. Where opening  20  is a vertical opening (e.g., a vertical doorway), as illustrated in  FIG. 1 , shaft  120  may be configured to be mounted horizontally above opening  20  on wall  10 . Shaft  120 , in certain embodiments, has a length that is equal to or greater than the width of opening  20 . Shaft  120  may further be connected to a system configured to rotate shaft  120  in order to wind/unwind flexible curtain  110 , such as a motor or pulley system (not shown). In one embodiment, shaft  120  is coupled to a sensor and the shaft is configured to rotate in response to a signal from the sensor. For example, the sensor (e.g., smoke detector, gas detector) may, in response to a sensing event (e.g., detecting smoke or gas), send a signal to an actuator (e.g., motor, pulley system) to rotate shaft  120  to wind/unwind flexible curtain  110 . Flexible curtain  110  generally includes a first end  112  coupled to shaft  120  (e.g., via adhesive, welding, press fit), a second end  114  opposite first end  112 , and first and second side edges  116   a ,  116   b  which extend between first end  112  and second end  114 . Moreover, flexible curtain  110  includes a front surface  118   a , which for example may face towards the interior of the building or structure, and a back surface  118   b  opposite front surface  118   a , which for example may face toward opening  20 . 
     In some embodiments, roll-up door assembly  100  further includes first and second guides  130   a ,  130   b  which are configured to receive side edges  116   a ,  116   b  of flexible curtain  110 , respectively. Guides  130   a ,  130   b  in some embodiments may be configured to be mounted on wall  10  along the lateral sides of opening  20  and may define tracks through which side edges  116   a ,  116   b  of flexible curtain  110  may slide during operation. In some embodiments, guides  130   a ,  130   b  may be mounted outside a frame that defines opening  20  (e.g., around a door frame). In some embodiments, guides  130   a ,  130   b  are mounted directly adjacent to and may abut a frame that defines opening  20 . In other embodiments, guides  130   a ,  130   b  may be mounted on or within a frame that defines opening  20  (e.g., on the sides of a door frame). In one embodiment, where opening  20  is a vertical opening, guides  130   a ,  130   b  are configured to be oriented vertically. In other embodiments, where opening  20  is a horizontal opening, guides  130   a ,  130   b  are configured to be oriented horizontally. In some embodiments, guides  130   a ,  130   b  are configured to be mounted parallel to each other on either side of opening  20  and spaced apart by a predetermined distance that is sufficient to cover opening  20 . In further embodiments, each of guides  130   a  and  130   b  are configured to be mounted perpendicular to shaft  120 . In some embodiments, guides  130   a ,  130   b  are adapted to direct flexible curtain  110  as flexible curtain  110  is coiled and uncoiled and to help seal the sides of opening  20 . Guides  130   a ,  130   b  may be constructed from metal or other suitable materials known in the art. In some embodiments, guide  130  includes a fascia attachment element (e.g., anchor, screw, weld, adhesive). 
       FIG. 1  particularly shows flexible curtain  110  in a deployed position wherein flexible curtain  110  has been uncoiled from shaft  120  sufficiently to cover opening  20 . In the illustrated embodiment, second end  114  of flexible curtain  110  has been extended away from shaft  120  sufficiently to reach end  22  of opening  20 . For example, in some embodiments, end  22  may be at the floor of the building or structure where opening  20  is a vertical doorway. In other embodiments, where opening  20  is a window, end  22  may be a window sill. 
       FIG. 2  shows flexible curtain  110  in an at least partially retracted position according to one embodiment. In this embodiment, flexible curtain  110  has been partially coiled around shaft  120  such that second end  114  of flexible curtain  110  is retracted away from end  22  of opening  20  toward shaft  120  sufficiently to allow access through opening  20 . Coiling of flexible curtain  110  can be achieved by rotating shaft  120  in a first direction, which can be accomplished automatically or manually according to some embodiments. For example, as noted above, shaft  120  may be connected to a motor or pulley system (not shown) configured to rotate shaft  120 . Rotating shaft  120  in a direction opposite the first direction will uncoil flexible curtain  110  and will transition flexible curtain  110  from the retracted position to the deployed position shown in  FIG. 1 . As flexible curtain  110  moves between the retracted position and the deployed position and vice versa, side edges  116   a ,  116   b  of flexible curtain slide  110  slide through guides  130   a ,  130   b  (e.g., sliding partly or entirely through), which help guide the movement of flexible curtain  110 . 
     As noted above, a problem that may be encountered with typical roll-up doors occurs when the flexible curtain gets pulled out of the guides positioned on the lateral sides of the opening. This problem prevents the opening from being properly covered by the flexible curtain. The roll-up door according to preferred embodiments of the present invention includes one or more retention members (e.g., retention bands) configured to secure flexible curtain  110  to guides  130   a ,  130   b  which can be mounted along (e.g., coupled to, integral with or attached directly to) at least a portion of the side edges  116   a ,  116   b  of flexible curtain  110 . In some embodiments, the one or more retention members (e.g., retention bands) cooperate with guides  130   a ,  130   b  to create a seal that is configured to prevent or retard smoke and/or fire from passing through opening  20  when flexible curtain  110  is in the deployed state. 
     With reference now to  FIGS. 3 and 4 , which shows a portion of flexible curtain  110  according to some embodiments, a roll-up door of the present invention may include at least a first retention band  140   a  mounted along at least a portion of first side edge  116   a  of flexible curtain  110  on front surface  118   a . First retention band  140   a  is configured to resist or prevent pull-out of first side edge  116   a  from first guide  130   a  during use. In certain preferred embodiments, a second retention band  140   b  can be also mounted along at least a portion of second side edge  116   b  of flexible curtain  110  on front surface  118   a . Second retention band  140   b  is configured to resist or prevent pull-out of second side edge  116   b  from second guide  130   b  during use and may be similarly configured as and be arranged symmetrically with first retention band  140   a . In alternative embodiments, described further below, first and second retention bands  140   a ,  140   b  may be mounted on back surface  118   b  of flexible curtain  110 . In some embodiments, first and second retention bands  140   a ,  140   b  include tapered ends  142   a ,  142   b  proximate second end  114  of flexible curtain  110 . In one embodiment, one benefit of tapered ends  142   a ,  142   b  includes facilitating smooth operation of roll-up door assembly  100 , for example, by avoiding sharp corners that may protrude from flexible curtain  110 . Such sharp corners may be susceptible to hang-ups or gouging of guides  130   a ,  130   b  during operation, or even result in injury during installation. In further embodiments, flexible curtain  110  includes reinforcement bands  152  that extend along first and second side edges  116   a ,  116   b  to which first and second retention bands  140   a ,  140   b  may be attached. 
       FIGS. 5 and 6  provide partial perspective views showing a portion of first retention band  140   a  positioned along first side edge  116   a . It should be understood that second retention band  140   b  may be similarly configured with respect to second side edge  116   b . In some embodiments, first and second retention bands  140   a ,  140   b  include a strip of elastic material (e.g. spring steel, aluminum, plastic, rubber or other suitable elastic material) that is capable of deflecting toward or away from flexible curtain  110 . In some embodiments, first and second retention bands  140   a ,  140   b  include material that is thin enough to enable tight, smooth coiling, elastic enough to retain the necessary curved shape when deployed (even after being held in the flattened position for extended periods), and strong enough to resist pullout from guides  130   a ,  130   b  when force is applied. In some embodiments, as noted previously, roll-up door assembly  100  may be configured to contain fire and/or smoke. According to some such embodiments, first and second retention bands  140   a ,  140   b  are configured to withstand temperatures of 400° F. or greater, preferably 1800° F. or greater. Therefore, in some embodiments, first and second retention bands  140   a ,  140   b  are made from materials configured to be retain their strength at these temperatures, and may be made from fire-resistant or flame retardant materials. In some embodiments, where first and second retention bands  140   a , and  140   b  have elevated temperature requirements, steel may be used for retention bands  140   a ,  140   b . In other embodiments, plastics or rubber may be used for retention bands  140   a ,  140   b  where there are no elevated temperature requirements. 
     As shown in  FIGS. 5 and 6 , in some embodiments first retention band  140   a  includes an inner surface  144  at least partially facing towards flexible curtain  110  (e.g., at least partially facing towards front surface  118   a ) and an outer surface  146  opposite inner surface  144 . In further embodiments, first retention band  140   a  further includes a fixed edge  148  attached to flexible curtain  110  and a free edge  150  that is opposite fixed edge  148  and movable relative to fixed edge  148 . In some embodiments, fixed edge  148  may be generally parallel to first side edge  116   a . In some embodiments, fixed edge  148  may be aligned with first side edge  116   a . In other embodiments, fixed edge  148  may be spaced a certain distance from first side edge  116   a.    
     In certain embodiments, fixed edge  148  may be attached to flexible curtain  110  by any suitable means known in the art. In some embodiments, mechanical fasteners (e.g., screws, bolts, rivets, staples, etc.) may be used to attach fixed edge  148  to flexible curtain  110 . In other embodiments, an adhesive is used to attach fixed edge  148  to flexible curtain  110 . In yet other embodiments, fixed edge  148  may be welded, soldered, or brazed onto front surface  118 , for example, at first side edge  116   a . In some embodiments, as noted above, flexible curtain  110  may include reinforcement band  152  along first side edge  116   a  to which fixed edge  148  is attached (e.g., riveted, welded, etc.). In some embodiments, reinforcement band  152  is configured to provide reinforcement to flexible curtain  110  along first side edge  116   a . In some embodiments, reinforcement band  152  provides a stronger material to which fixed edge  148  of first retention band  140   a  may be attached. A further reinforcement band may also be provided along second side edge  116   b  for the attachment of second retention band  140   b  in a similar manner. In some embodiments, reinforcement band  152  may be made from material that would provide added strength to the side edges  116   a ,  116   b  of flexible curtain  110  while still being flexible enough to also coil around shaft  120 . In some embodiments, reinforcement band  152  is a metal band (e.g., steel, aluminum, etc). In some embodiments, reinforcement band  152  is a metal band that is configured to be welded to first retention band  140   a . In other embodiments, other materials such as rubber, plastic, strong fabric, scrim or mesh may be used for reinforcement band  152 . In yet other embodiments, first retention band  140   a  may be integrally formed with reinforcement band  152 . Reinforcement band  152  may have any suitable thickness which allows it to coil tightly and smoothly on shaft  120 . For example, in some embodiments, reinforcement band  152  may be made of steel and have a thickness in the range of about 0.003 inches to about 0.01 inches. Other thicknesses may be selected depending on the material used for reinforcement band  152 . 
     As shown in the illustrated embodiments of  FIGS. 5 and 6 , first retention band  140   a  may includes a substantially curved contour extending between fixed edge  148  and free edge  150 , for example, when flexible curtain  110  is in a deployed position. In some embodiments, outer surface  146  may have a concavely curved contour extending between fixed edge  148  and free edge  150 , while inner surface  144  may have a convexly curved contour extending between fixed edge  148  and free edge  150 . In one embodiment, at least a portion of the inner surface  144  of the retention band  140  is positioned against (e.g., pressed against) the flexible curtain  110 . In one embodiment, substantially all of the inner surface  144  of the retention band  140  is pressed against the flexible curtain  110 . 
     In some embodiments, first retention band  140   a  is configured to transition from an extended or curved configuration as exemplified in  FIGS. 5 and 6  toward a flattened configuration when a sufficient force is applied against first retention band  140   a , for example, when a sufficient force is applied against outer surface  146 . In some embodiments, in order to ensure that first retention band  140   a  is able to coil tightly and smoothly, the force required to flatten first retention band  140   a  should be less than the force applied to first retention band  140   a  when it is coiled onto shaft  120 . Otherwise, first retention band may retain its curved shape when flexible curtain  110  is rolled onto shaft  120  which could prevent smooth coiling. In some embodiments, the force required to flatten first retention band  140   a  will vary based on the materials used and geometry of first retention band  140   a . In one embodiment, first retention band  140   a  has an elasticity (e.g., a Young&#39;s Modulus) selected to be low enough to ensure that retention band  140   a  will substantially flatten when flexible curtain  110  is coiled about shaft  120  such that flexible curtain  110  rolls substantially flat. Yet, the elasticity is high enough so that first retention band  140   a  springs open as the curtain is uncoiled from the shaft. In one embodiment, the elasticity is a function of the hanging weight of flexible curtain  110  (e.g., on vertical units) or the resistance of pulling flexible curtain  110  along the guides (e.g., on horizontal units). In one embodiment, the first retention band  140   a  has a Young&#39;s Modulus of about 0.01-200 GPa, 1-10 GPa, 10-50 GPa, 50-100 GPa, or 100-200 GPa. In one embodiment, the first retention band  140   a  has a Young&#39;s Modulus of at least 0.01 GPa, 0.1 GPa, 1 GPa, 5 GPa, 10 GPa, 15 GPa, 20 GPa, 25 GPa, 30 GPa, 35 GPa, 40 GPa, 45 GPa, 45 GPa, 55 GPa, 60 GPa, 65 GPa, 70 GPa, 75 GPa, 80 GPa, 85 GPa, 90 GPa, 95 GPa, 100 GPa, 110 GPa, 120 GPa, 130 GPa, 140 GPa, 150 GPa, 175 GPa, or 200 GPa. 
       FIGS. 7A-7C  are cross-sectional views showing the profile of first retention band  140   a  according to some embodiments as first retention band  140   a  transitions from an expanded (e.g., curved) configuration ( FIG. 7A ) to a flattened configuration ( FIG. 7C ) in response to a force F depicted by the arrow in  FIGS. 7 b    and  7 C. As illustrated, first retention band  140   a  is configured to deflect towards flexible curtain  110  in response to force F. In particular, fixed end  150  is configured to move towards until inner surface  144  of first retention band  140   a  abuts against front surface  118   a  of flexible curtain  110 . Upon removal of force F, first retention band is preferably configured to spring back to the original expanded (e.g., curved) configuration ( FIG. 7A ) due to its elastic nature. By being configured to substantially flatten, first retention band  140   a  according to these embodiments is configured to be coiled with flexible curtain  110  around shaft  120  during operation of the roll-up door. 
       FIG. 8  is a partial perspective view showing flexible curtain  110  having first retention band  140   a  that is partially wound around shaft  120  in accordance with one embodiment of the present invention. As flexible curtain  110  is being coiled around shaft  120  (e.g., when flexible curtain  110  moves from the deployed position to the retracted position), first retention band  140   a  is configured to be positioned against (e.g., pressed toward) the cylindrical face of shaft  120  and transition from a expanded (e.g., curved) configuration to a flattened configuration. Preferably the first retention band  140   a  is sufficiently thin to allow for tight and smooth coiling around shaft  120 . In some embodiments, for example, first retention band  140   a  may be made from steel and have a thickness ranging from about 0.005 inches to about 0.01 inches. Other thicknesses may be selected for other materials. As flexible curtain  110  is being uncoiled from shaft  120  (e.g., when flexible curtain  110  moves from the retracted position to the deployed position), first retention band  140   a  is configured to transition from a flattened configuration to the expanded (e.g., curved) configuration. Second retention band  140   b  may be similarly configured on second side edge  116   b . In one embodiment, a ratio of a retention band thickness to a retention band width is about 1:10. In one embodiment, a ratio of a retention band thickness to a retention band width is about 1:1, about 1:2, about 1:3, about 1:4, about 1:5, about 1:7, about 1:9, about 1:15, about 1:20, about 1:25, about 1:40, or about 1:50. In one embodiment, a ratio of a retention band thickness to a retention band width is at least 1:1, at least 1:2, at least 1:3, at least 1:4, at least 1:5, at least 1:7, at least 1:9, at least 1:15, at least 1:20, at least 1:25, at least 1:40, or at least 1:50. In one embodiment, a ratio of a retention band thickness to a retention band width is about 1:1 to about 1:5, about 1:5 to about 1:10, about 1:10 to about 1:15, about 1:15 to about 1:20, about 1:20 to about 1:30, about 1:30 to about 1:40, about 1:40 to about 1:50, about 1:50 to about 1:100, or about 1:100 to about 1:1,000. 
     While  FIGS. 3-8  have shown first and second retention bands  140   a ,  140   b  positioned on front surface  118   a  of flexible curtain  110 , other embodiments may have first and second retention bands  140   a ,  140   b  positioned on back surface  118   b . According to these embodiments, first and second retention bands  140   a ,  140   b  would flex toward or away from back surface  118   b  during coiling/uncoiling. Moreover, in some such embodiments, outer surface  146  of first and second retention bands  140   a ,  140   b  would generally face towards the wall (e.g., wall  10  of  FIG. 2 ) having opening  20 . Such an arrangement may be desirable according to some embodiments depending on the available space for mounting roll-up door assembly  100 .  FIG. 9  is a partial perspective view showing flexible curtain  110  partially wound around shaft  120  according to one such alternative embodiment. In this embodiment, flexible curtain  110  and first retention band  140   a  can be wound onto shaft  120  in the opposing direction. Unlike  FIG. 8  which shows first retention band  140   a  mounted on front surface  118   a  of flexible curtain  110 , in the embodiment shown in  FIG. 9  first retention band  140   a  is mounted on back surface  118   b  of flexible curtain  110 . In this arrangement, first retention band  140   a  may be configured such that it is stretched around shaft  120  during coiling of flexible curtain  110  rather than being pressed toward the cylindrical face of shaft  120 . In other words, outer surface  146  of first retention band  140   a  faces away from shaft  120  as flexible curtain  110  is coiled around shaft  120 . As flexible curtain  110  is coiled around shaft  120 , first retention band  140   a  is configured to transition from a expanded (e.g., curved) configuration to a flattened configuration. As flexible curtain  110  is being uncoiled from shaft  120 , first retention band  140   a  is configured to spring back from a flattened configuration to the expanded (e.g., curved) configuration. 
     With reference now to  FIG. 10 , first retention band  140   a  in certain preferred embodiments is configured to secure flexible curtain  110  to first guide  130   a . In some embodiments, first guide  130   a  defines a track  132  configured and dimensioned to receive at least a portion of first side edge  116   a  of flexible curtain  110 . In some embodiments, track  132  is further configured and dimensioned to receive at least a portion of first retention band  140   a . In some embodiments, track  132  has a width W 1  that is sufficient to accommodate first retention band  140   a  in its expanded (e.g., curved) configuration. In some embodiments, width W 1  is larger than the distance  151  between free edge  150  and flexible curtain  110  when first retention band  140   a  is in its expanded (e.g., curved) configuration. First guide  130   a , according to some embodiments, further includes a throat  134  through which first side edge  116   a  and first retention band  140  may be received. In some embodiments, throat  134  has a throat wall  153  and an opening width W 2  between a guide wall  155  and the throat wall  153  that is less than W 1  and less than a distance between free edge  150  and flexible curtain  110  when first retention band  140   a  is in the expanded (e.g., curved) configuration as illustrated. In order to insert first side edge  116   a  into first guide  130   a  according to certain embodiments, first retention band  140   a  is bent or deflected towards flexible curtain  110  such that first retention band  140   a  transitions from the expanded (e.g., curved) configuration toward the flattened configuration (as illustrated in  FIGS. 7 b    and  7 C). This allows first retention band  140   a  to assume a thinner profile to allow insertion through narrow throat  134 . Once first side edge  116   a  and first retention band  140   a  is received into track  132 , first retention band  140  is allowed to spring back to its expanded (e.g., curved) configuration. Since the distance  151  between free edge  150  and flexible curtain  110  increases above width W 2  of throat  134  when first retention band  140   a  moves (e.g., bends) back to its expanded (e.g., curved) configuration, first retention band  140   a  cannot be pulled out of first guide  130   a  through throat  134 . Accordingly, in some embodiments, first retention band  140   a  is capable of anchoring first side edge  116   a  within track  132  since first retention band  140   a  prevents it from being pulled out of track  132  through throat  134 . For example, the first retention band  140   a  is configured to contact the throat wall  153  to prevent the retention band from disengaging from first guide  130   a . In some embodiments, the distance between free edge  150  and flexible curtain  110  in the expanded (e.g., curved) configuration is at least 1.5 times width W 2 , at least 2 times width W 2 , or at least 3 times width W 2 . In some embodiments, width W 2  may be selected to be as small as possible while still allowing flexible curtain  110  to move freely through first guide  130   a  with minimal friction. In further embodiments, width W 1  may be selected to be sufficiently sized to provide clearance for first retention band  140   a  in the expanded (e.g., curved) configuration to minimize frictional contact between first retention band  140   a  and the walls of first guide  130   a . In some embodiments, first side edge  116   a  of curtain flexible curtain  110  is positioned within track  132  such that first retention band  140   a  is positioned as close to throat  134  as possible without resulting in excessive rubbing/friction during operation between first guide  130   a  and first retention band  140   a . Keeping first retention band  140   a  close to throat  134 , in some embodiments, may minimize the amount of billowing or sagging in flexible curtain  110  when pressure is applied against flexible curtain  110 . While the above discussion has focused on first retention band  140   a  and first guide  130   a  for ease of explanation, it should be understood that second retention band  140   b  and second guide  130   b  can be similarly configured. 
       FIG. 11  is a top perspective sectional view showing the position of a guide  130  along wall  10  relative to a frame  12  according to one example embodiment. Frame  12  attaches to and/or protrudes from wall  10  and may be, for example, a frame which surrounds a doorway or an elevator door. In some embodiments, frame  12  protrudes about 0.75 inches from wall  10 . As shown in this embodiment, guide  130  is mounted onto wall  10  immediately adjacent to frame  12 . In order to allow for the flexible curtain (not shown) to clear frame  12  during use while minimizing the footprint of guide  130 , guide  130  is preferably configured such that throat  134  just clears surface  14  of frame  12 . Therefore, in the embodiment shown, guide  130  protrudes from wall  10  a distance generally equal to distance at which frame  12  protrudes from the wall plus the width of throat  134  and the thickness of the material used to form guide  130 . Width W 1  of track  132  defined by guide  130  may be generally equal to or slightly less than the distance at which frame  12  protrudes from wall  10  plus the width of throat  134 . In order to use guide  130  in the arrangement shown in  FIG. 11 , the retention band of the flexible curtain should be configured such that it faces toward wall  10  in the deployed position within track  132 . Accordingly, the configuration shown in  FIG. 9  where first retention band  140   a  is positioned on back surface  118   b  of flexible curtain  110  may be particularly suited for use in this embodiment. 
     In one embodiment, the guide  130  is configured to be mounted adjacent an opening and the guide  130  is configured to receive a closure (e.g., a flexible curtain) that obscures the opening. In the embodiment of  FIGS. 15-16 , the guide  130  includes first element  190  and second element  204  configured to be coupled together. In one embodiment, first element  190  and second element  204  can be installed in stages, thus creating a secure attachment of the guide to a structure. In one embodiment, first element  190  is configured to be secured to a structure and the second element  204  is configured to be coupled to the first element such that the assembled guide  130  is coupled to the wall and configured to receive the flexible curtain and retention band. For example, the first element  190  and second element may include securements that include press fit securements having retaining features. One embodiment may include a first prong  192  and a second prong  194  each having a retaining feature  196  (e.g., a lip, shoulder) configured to mate (e.g., snap fit, inserted into) with a notch  198  in first and second channel walls  200 ,  202 . In one embodiment, the features shown may be reverse such that retention features of the first element  190  and second element  204  are reversed. In one embodiment, the throat  134  is defined by the space between the first element and the second element, as explained below. In one embodiment, the guide  130  is configured to movably receive the closure (e.g., the closure may slide, translate, rotate with respect to the guide while engaged with the guide). 
     In one embodiment, the first element  190  includes a first wall  206  configured to be secured to a structure (e.g., a wall, fascia, adjacent an elevator frame). For example, the first wall  206  may be coupled to the structure by an anchor  214  (e.g., a threaded fastener, a nail, heat stake, weld) such that the first element is fixed to the structure. In one embodiment, a proximal end  208  of each of the first prong  192  and second prong  194  are coupled to the first wall  206  (e.g., via adhesive, welding). In one embodiment, the first prong  192  and second prong  194  are configured to be at least partially compressed toward each other when the prongs are within the channel  212  to enhance the engagement of the retaining feature  196  and the notch  198 . For example, a distance between the distal ends  210  of the first prong  192  and second prong  194  when the may be reduced when the prongs  192 ,  194  are within the channel  212  compared to when the prongs are not in the channel. In one embodiment, the distance between the proximal ends  208  of the prongs  192 ,  194  is equal to the distance between the distal ends  210  of the prongs  192 ,  194  when the first element  190  is engaged with the second element  204 . In one embodiment, the distance between the proximal ends  208  of the prongs  192 ,  194  is equal to the distance between the distal ends  210  of the prongs  192 ,  194  when the first element  190  is engaged with the second element  204 . In one embodiment, the distal end  210  of at least one of the first element  190  and the second element  204  includes the retaining feature  196 . 
     In one embodiment, the second element  204  includes the channel  212  which is defined by the first channel wall  200  and second channel wall  202 . In one embodiment, the channel  212  is configured to receive the first prong  192  and second prong  194  to secure the second element  204  to the first element  190 . For example, a proximal end  218  of each of the first channel wall  200  and the second channel wall  202  may include the notch  198  such that the retaining feature  196  of the first prong  192  and second prong  194  are within the notch  198  when the prongs  192 ,  194  are within the channel  212  thereby preventing disengagement of the second element  204  from the first element  190 . In one embodiment, the distance between the proximal ends  218  of the channel walls  200 ,  202  is less than the distance between the distal ends  210  of the first and second prongs  192 ,  194  in the relaxed configuration such that the prongs  192 ,  104  are slightly compressed when the prongs are in the channel  212  thus creating a biasing force that enhances (e.g., by forcing the retaining feature  196  further into the notch  198 ) the engagement of the retaining feature  196  and the notch  198  ( FIG. 16 ). In one embodiment, the first channel wall  200  and second channel wall  202  include a plurality of notches  198  between the proximal and distal ends  216 ,  218  of the channel walls  200 ,  202  such that the width W 1  of the space between the first wall  196  and the guide wall  155  may be selected based on the thickness of the flexible curtain  110 . For example, the retaining feature  196  may be selectively engaged with a notch  198  corresponding to a desired width W 1 . 
     In one embodiment, a closure system is configured to partially or completely seal an opening and includes a closure means (e.g., flexible curtain  110 ) for obscuring (completely or partially) the opening. In one embodiment, the closure system includes a receiving means (e.g., guide  130 ) for receiving a free end of the closure means. In one embodiment, the closure system includes a retaining means (e.g. retention band  140 ) for coupling the closure means to the receiving means. In one embodiment, the closure system includes a spring means (e.g., retention band  140 ) for coupling the closure means to the receiving means and the spring means is configured to move from a flattened configuration to an extended configuration. In one embodiment, the closure system includes a strengthening means (e.g., reinforcement band  152 ) for enhancing the engagement of the retaining means to the closure means. 
     In some embodiments, first and second retention bands  140   a ,  140   b  are each configured to be a single continuous component. In other embodiments, a retention band may include a plurality of segments. For example, as illustrated in the embodiment of  FIG. 12 , a retention band according to one embodiment includes a plurality of segments  240   a - 240   c  with adjacent segments being separated by a gap. The total number of segments included on the retention band will depend on the overall length of the retention band. In some embodiments, each segment  240   a - 240   c  may be from about 5 inches to about 6 inches in length, for example, which may be wrapped on a shaft with a diameter of about 4.5 inches. Other dimensions for the segments can be selected depending on other shaft diameters or materials used. In further embodiments, the gaps between adjacent segments may be minimized in order to provide the maximum amount of retention and sealing benefits when flexible curtain  110  is in the deployed position. Each of the plurality of segments may independently deflect and, according to some embodiments, having a plurality of segments  240   a - 240   c  rather than a single continuous retention band may improve coiling of flexible curtain  110 , especially when thicker materials are utilized. In some embodiments, having a segmented retention band allows each segment to shift slightly which may help accommodate for the slightly different diameters caused by the variations in thickness during coiling and uncoiling. In some embodiments, having a segmented retention band may increase the flexibility of the side edge and allow for better coiling. 
     While first retention band  140   a  shown in  FIGS. 5-10  may have an outer surface  146  with a concavely curved contour and an inner surface  144  having a convexly curved contour, other shapes may be used according to additional embodiments of the present invention.  FIGS. 13A and 13B  show example alternative profile shapes that may be utilized for a retention band.  FIG. 13A , for example, shows a retention band  340   a  having a convexly curved outer surface  346  and a concavely curved inner surface  344  in the deployed position. In a further example, shown in  FIG. 13B , retention band  440   a  may have substantially planar inner and outer surfaces  444  and  446 . In this embodiment, retention band  440   a  may be angled with respect to flexible curtain  110  at an acute angle α in the deployed position (e.g., about 30 degrees to about 60 degrees, or about 40 degrees to about 50 degrees). Apart from the profile shapes, other features and properties of retention bands  340   a  and  440   a  may be the same as those described for retention bands  140   a ,  140   b.    
     In the embodiment shown in  FIG. 14A-14C , the flexible curtain  110  is configured to be wrapped around the retention band  140  to increase the strength of the attachment of the curtain to the retention band. For example, the flexible curtain  110  may be wrapped from the outer surface  146  of the retention band  140 , around the fixed edge  148 , and onto the inner surface  144  of the retention band  140  and affixed thereto such that as a force is applied to the flexible curtain  110 , the force is distributed to the bond between the flexible curtain and the retention band over a greater surface area compared to previously described embodiments. In some embodiments, the flexible curtain  110  is affixed to the retention band by adhesive, welding, fasteners, etc. In one embodiment, the portion  160  of the flexible curtain  110  wrapped onto the outer surface  146  has a length  162  of about ¾″ to about 1″. In some embodiments, the selected length  162  may be influenced by one or more physical properties of the flexible curtain (e.g., material composition, thickness, heat resistance) or the geometry of the opening (e.g., length, height). In one embodiment, a ratio of the length  162  between the first edge  116  and an end  164  of the portion  160  to a length between the first side edge  116   a  and second side edge  116   b  of the flexible curtain  110  is about 1:75. In one embodiment, the end  164  of the flexible curtain  110  is configured to be aligned with the free end  150  of the first retention band  140   a . For example, an end  164  of the portion  160  of the flexible curtain  110  and the free end  150  may be aligned such that the end  164  and free end  150  are co-planar when the flexible curtain  110  is secured to the retention band  140 . In one embodiment, the free end  150  and end  164  are offset from each other. In one embodiment (not shown), the flexible curtain  110  is configured to wrap around the retention band  140  from the inner surface  144  of the flexible band  140 , over the free end  150  onto the outer surface  146 , and over the fixed edge  148  onto the inner surface  144 . 
     In one embodiment, a guide assembly  175  is mounted adjacent to an elevator frame and may be mounted to the face of a wall, exposed, or hidden (e.g., under sheetrock, wood or masonry fascia). For example, as shown in  FIG. 19 , the guide assembly  175  may be mounted in a recess  183  between fascia  185  and a wall  193 . Guide assembly  175  is similar to guide  130  but guide assembly  175  includes a return  189  and the first wall  206  is coupled to the second prong  194  between the proximal and distal end of the prong. In one embodiment, the first wall  206  may prevent over insertion of the first and second prongs into the channel because the channel walls contact the first wall  206  impeding further movement of the prongs into the channel. In one embodiment, the return  189  is configured to be adjacent a sidewall of the fascia  185 . For example, the return  189  may extend away from guide wall  155  such that the return  189  is adjacent the sidewall of the fascia  185  when the guide wall is positioned adjacent a rear surface of the fascia and the guide is within the recess  183 . In one embodiment, the elevator jamb  187  is configured to at least partially retain the guide assembly  175  within the recess  183 . For example, the elevator jamb  187  may include a bump  197  adjacent the second prong  194  that prevents guide assembly  175  from being pulled out of recess  183 . In one embodiment, the return  189 , a face  195  of the spacer wall  214 , and the elevator jamb  187  are co-planar or nearly co-planar for an aesthetically pleasing installation. As shown in  FIG. 20 , in one embodiment, the guide (not shown in  FIG. 20 ) may be behind the fascia  185  adjacent an elevator and extend from the floor to the ceiling. In one embodiment, a portion  183  of the fascia  185  above the elevator doors may be recessed compared to the other sections of the fascia such that the flexible curtain  110  is in a plane in front of the recessed portion  183  and behind the fascia  185 . In one embodiment, a guide includes a fascia engaging component (e.g., return  189 ), a channel having an opening (e.g., throat  134 ) configured to receive a door edge (e.g., retention band  140 ), and a retention surface (e.g., throat wall  153 ) adjacent the channel configured to abut a free end of a retention component coupled to the door edge. 
     In some embodiments, a pull out strength may be observed when the flexible curtain  110  and retention band  140  are connected to the guide  130  as previously described and a force is applied to the flexible curtain to pull the flexible curtain until it is disengaged from either the guide or the retention band. In one embodiment, the flexible curtain  110  (e.g., a plastic flexible curtain) has a pull out strength of about 6.0-6.55 pounds per linear inch of retention band at a temperature of about 65° F. to about 70° F. In one embodiment, the flexible curtain  110  (e.g., a plastic flexible curtain) has a pull out strength of about 1.5-2.0 pounds per linear inch of retention band at a temperature of about 400° F. In one embodiment, the flexible curtain  110  (e.g., a plastic flexible curtain) coupled to the retention band has a pull out strength of about 11.0-11.5 pounds per linear inch of retention band at a temperature of about 60° F. to about 70° F. In one embodiment, the flexible curtain  110  (e.g., a plastic flexible curtain) coupled to the retention band has a pull out strength of about 1.5-2.0 pounds per inch at a temperature of about 400° F. In one embodiment, the flexible curtain  110  (e.g., a woven fiberglass flexible curtain) coupled to the retention band has a pull out strength of about 1.0-1.5 pounds per linear inch of retention band at a temperature of about 1800° F. In one embodiment, the flexible curtain  110  is coupled to the retention band and has a pull out strength of at least 1.1, 1.2, 1.3, 1.4, 1.5, 2.0, 2.5, 3.0, 3.5, 4.0, 4.5, 5.0, 6.0, 7.0, 8.0, 9.0, 10.0, 15.0, 20.0, 25.0, 30.0, 40.0, or 50.0 pound per inch at a temperature of about 400° F. In some embodiments, the flexible curtain  110  is configured to comply with UL (Underwriter&#39;s Laboratories) 1784 conditions. 
     In the embodiment shown in  FIGS. 17-18 , the flexible curtain  110  is configured to be opened either automatically (e.g., by an actuator in response to a signal, such as a smoke detector, a fire detector initiated signal or an all-clear signal) or manually by a user. For example, the flexible curtain may include an activator (e.g., a pushbutton, switch, toggle, voice command receiver, potentiometer) configured to be engaged by a user. The activator may be configured to send a signal (e.g., electronic signal) to an actuator (e.g., motor, piston) which is configured to move the flexible curtain to the retracted position. In one embodiment, the activator  170  includes a pushbutton configured to send a signal to a motor (not shown). In one embodiment, the activator  170  is configured to be in electrical communication (e.g., wired, wireless communication) with the motor such that the activator can send a signal to the motor. In one embodiment, the motor is configured to rotate the shaft, thereby moving the flexible curtain  110  to the retracted position. For example, the activator  170  may be a pushbutton connected via wires to the motor (e.g., brushless DC motor, stepper motor, induction motor), which may be coupled to the shaft (e.g., via gears, chain) such that the motor rotates the shaft in response to a signal from the activator  170 . In one embodiment, the activator  170  may be engaged by the user from both the front surface  118   a  and the back surface  118   b  of the flexible curtain  110 . In one embodiment, the activator (e.g., an open switch) is a screen-mounted and engageable by user on either side or both sides of the screen. In one embodiment, the flexible curtain  110  includes an activator  170  on the front surface  118   a  and a second activator  170  on the back surface  118   b  such that the flexible curtain  110  is an uninterrupted protective barrier to heat, smoke, and/or fire. 
     In one embodiment, the activator  170  is embedded within the flexible curtain  110 . For example, the activator  170  may be within an aperture (not shown) in the flexible curtain  110  such that the activator  170  extends from the front surface  118   a  to the back surface  118   b  of the flexible curtain. In one embodiment, the activator  170  is coupled (e.g., via adhesive, welding, heat stakes, connectors) to a surface of the flexible curtain  110 . In one embodiment, the flexible curtain includes a sheet  176  configured to be positioned over the activator  170 . For example, the activator  170  may be attached to the flexible curtain  110  (e.g., via adhesive, heat stake, threaded connector) and the sheet  176  may be positioned over the activator  170  and coupled to the flexible curtain  110  (e.g., via adhesive, heat seal). 
     In one embodiment, the flexible curtain  110  includes a bottom bar  172 . Bottom bar may be configured to seal a space between the bottom of the flexible curtain and a floor ( FIG. 17-18 ). For example, the bottom bar  172  may be a seal (e.g., brush seal, a rubber seal) configured to prevents the unwanted migration of smoke and/or fire when the flexible curtain is in the extended position by filling a gap between the bottom of the flexible curtain  110  and the floor. In one embodiment, the flexible curtain  110  includes a lift strap  178  configured to be engaged by a user to manually move the flexible curtain  110  between the extended position and the retracted position ( FIG. 18 ). For example, the lift strap  178  may be a strap or handle coupled to the bottom bar  172  such that a user can grasp and pull the lift strap  178  to move the flexible curtain to the retracted position. In one embodiment, the lift strap  178  is coupled to the bottom bar  172  by adhesive, anchors, etc. In one embodiment, a retainer  180  is configured to at least temporarily secure a free end of the lift strap  178  to the flexible curtain  110  such that the lift strap does not snag when the lift strap is not in use. For example, the retainer  180  may be tape with adhesive backing or a mechanical hook and loop fastener (e.g., Velcro) that attaches to the flexible curtain  110 . In one embodiment, the flexible curtain  110  includes a lift strap  178  on each of the front surface  118   a  and the back surface  118   b  such that a user standing on either side of the flexible curtain  110  can raise the curtain. Bottom bar  172  may be configured to retain flexible curtain  110  in guides and to seal curtain  110  at sill  182 . Bottom bar  172  may be further configured to terminate upward travel at an elevator opening flush to fascia or at ceiling height and may be finished to match those surfaces, 
     It should be understood that various changes, substitutions, and alterations can be made herein without departing from the spirit and scope of the invention as defined by the appended claims. It should also be apparent that individual elements identified herein as belonging to a particular embodiment may be included in other embodiments of the invention. Moreover, the scope of the present application is not intended to be limited to the particular embodiments of the process, machine, manufacture, and composition of matter, means, methods and steps described in the specification. As one of ordinary skill in the art will readily appreciate from the disclosure herein, processes, machines, manufacture, composition of matter, means, methods, or steps, presently existing or later to be developed that perform substantially the same function or achieve substantially the same result as the corresponding embodiments described herein may be utilized according to the present invention.