Patent Publication Number: US-2022221133-A1

Title: Explosion protected luminaire

Description:
PRIORITY CLAIM 
     The present application claims the benefit of priority of U.S. Provisional Patent Application Ser. No. 63/136,362, titled “Explosion Protected Luminaire,” filed Jan. 12, 2021, which is incorporated herein by reference. 
    
    
     BACKGROUND 
     The application relates to luminaires and components for luminaires. 
     Light fixtures, or luminaires, include electric light sources and provide an aesthetic and functional housing in both interior and exterior applications. Luminaire enclosures often comprise enough volume to close in a gas between a light emitting element(s) and a lens. Therefore, where luminaires are used in environments containing explosive gas, legal regulations sometime require luminaires to qualify for safe use in such an environment. Qualification for safe use of such a luminaire enclosure in an environment containing explosive gas may include a requirement that any flames or hot gas resulting from the ignition of explosive gas closed into the luminaire enclosure is encapsulated by the luminaire enclosure. That is, the requirement may be that the luminaire enclosure be capable of protecting an external environment from being affected by an explosion occurring within the luminaire enclosure (e.g. an explosion-tight or explosion encapsulating enclosure). 
     SUMMARY 
     According to an exemplary embodiment, a luminaire includes an explosion encapsulating luminaire enclosure including a luminaire enclosure lens. 
    
    
     
       BRIEF DESCRIPTION OF DRAWINGS 
         FIG. 1  is a sectional side view of a luminaire enclosure. 
         FIG. 2  is a front view of the luminaire enclosure. 
         FIG. 3  is a view of a pcb board, LED array, and LED protective lens array configuration in an explosion protected luminaire enclosure. 
         FIG. 4  is a detailed view of a luminaire enclosure lens securing structure of the luminaire enclosure cover. 
         FIG. 5 a    is a top view of an LED protective lens array. 
         FIG. 5 b    is an underside view of an LED protective lens array including flame path gaps. 
         FIG. 5 c    is a side view of an LED protective lens array. 
         FIG. 5 d    is a detailed view of a LED protective lens design. 
         FIG. 6 a    is a perspective view of a luminaire comprising an explosion encapsulating luminaire enclosure. 
         FIG. 6 b    is a top view of a luminaire comprising an explosion encapsulating luminaire enclosure. 
         FIG. 7 a    is a perspective view of a luminaire comprising an explosion encapsulating luminaire enclosure. 
         FIG. 7 b    is a top view of a luminaire comprising an explosion encapsulating luminaire enclosure. 
         FIG. 8 a    is a top view of a standalone battery indicator light lens. 
         FIG. 8 b    is a sectional side view of a standalone battery indicator light lens. 
     
    
    
     DETAILED DESCRIPTION 
     Before any embodiments are explained in detail, it is to be understood that embodiments described and illustrated are not limited in their application to the details of construction and the arrangement of components set forth in the following description or illustrated in the following drawings. The embodiments described and illustrated may be practiced or carried out in various ways and other embodiments are possible. 
     Also, it is to be understood that the phraseology and terminology used herein are for the purpose of description and should not be regarded as limiting. The use of “including,” “comprising,” or “having” and variations thereof are meant to encompass the items listed thereafter and equivalents thereof as well as additional items. Unless specified or limited otherwise, the terms “mounted,” “connected,” “supported,” and “coupled” and variations thereof are used broadly and encompass both direct and indirect mountings, connections, supports, and couplings. As used within this document, the word “or” may mean inclusive or. As a non-limiting example, if it were stated in this document that “item Z may comprise element A or B,” this may be interpreted to disclose an item Z comprising only element A, an item Z comprising only element B, as well as an item Z comprising elements A and B. 
     Various embodiments described herein are directed to luminaire components that prevent a transmission of flames or hot gas from the inside of a luminaire enclosure to the outside of a luminaire enclosure due to an explosion occurring within the luminaire enclosure. In certain aspects, the luminaire enclosure can be used in an environment containing explosive gas, for example, in specialized lab work, testing applications, or high-risk areas such as mines or accelerant production or processing applications. A luminaire inside the luminaire enclosure may include light emitters configured to emit light directly through a luminaire enclosure lens (e.g. LEDs). This application discusses components that can be used to prevent explosive flame or hot gas transmission from the inside of a luminaire enclosure to the outside of a luminaire enclosure, thereby yielding an explosion encapsulating luminaire enclosure. A specialized luminaire enclosure that protects against internal explosions resulting in a transmission of an internal flame or hot gas to the exterior of the luminaire results while still facilitating a transmission of light from the interior of the luminaire enclosure to the exterior of the luminaire enclosure can be achieved by the principles disclosed herein. Accordingly, the components and assemblies described herein can be safely integrated with systems that operate in the presence explosive gas. 
       FIG. 1  illustrates a sectional side view of a luminaire system  100  comprising a luminaire enclosure  102  including a luminaire enclosure backing  104  and a luminaire enclosure cover  106 . The luminaire enclosure backing  104  and luminaire enclosure cover  106  are secured together in a manner that encapsulates any flame or explosion that occurs within the luminaire enclosure  102  and thereby prevents any such flame or explosion from escaping the luminaire enclosure  102  at any point at which the luminaire enclosure backing  104  and luminaire enclosure cover  106  meet. Moreover, the luminaire enclosure  102 , when assembled, is capable of fully encapsulating any explosion that may occur within the luminaire enclosure  102  according to a protective standard. For example, the explosion encapsulating protective standard of the luminaire enclosure  102  may be the Ex d standard. Under this and other protective standards, an enclosure must be able to encapsulate an explosion and allow flue gasses to escape after cooling enough to eliminate or greatly reduce the risk of igniting a flame or causing an explosion outside of the enclosure. A luminaire enclosure lens  112 , disposed in the luminaire enclosure  102 , allows light to be transmitted from the inside of the luminaire enclosure  102  to the outside of the luminaire enclosure  102  while also maintaining the explosion encapsulating protective standard of the luminaire enclosure  102 . 
     In the embodiment shown, an encapsulating gasket  108  is disposed between the luminaire enclosure backing  104  and the luminaire enclosure cover  106 , thereby further ensuring that no hot gas or flame is transmitted from the inside of the luminaire enclosure  102  to the outside of the luminaire enclosure  102  as a result of an explosion. Specifically, the encapsulating gasket  108  ensures that no hot gas or flame is transmitted from the inside of the luminaire enclosure  102  to the exterior of the luminaire enclosure  102  via a seam of the luminaire enclosure  102  in which the encapsulating gasket  108  is disposed. In the embodiment shown, a seam where the luminaire enclosure backing  104  and the luminaire enclosure cover  106  meet forms a sufficiently lengthy outer flame path  147  joining the interior of the luminaire enclosure  102  to the exterior of the luminaire enclosure. The outer flame path  147  helps to mitigate the transmission of flames or hot gasses from the interior to the exterior of the luminaire enclosure  102  by suffocating flames and forcing hot gasses to cool before exiting the luminaire enclosure. The luminaire enclosure cover  106  includes a lens accommodating window  114  having at least an outer bezel lip  116 . In the embodiment shown, the luminaire enclosure lens  112  is cemented into place within a lens accommodating window  114  of the luminaire enclosure cover  106 , against the outer bezel lip  116 , by a sealing agent  118 . The sealing agent  118  may be a silicone sealant adhesive, but may include other sealing agents. In some embodiments, the luminaire enclosure cover  106  secures the luminaire enclosure lens  112  to the luminaire enclosure backing  104 , by sandwiching the luminaire enclosure lens  112  between the luminaire enclosure cover  106  and luminaire enclosure backing  104  or an extension of either (e.g. spacer portion  127 ). In other embodiments, the lens accommodating window  114  also includes an inner bezel lip (not shown). In other embodiments, the luminaire enclosure lens  112  may be retained between the outer bezel lip  116  and an inner bezel lip (not shown) of the lens accommodating window  114 . 
     In the embodiment shown, the cementing of the luminaire enclosure lens  112  into the lens accommodating window  114  by the sealing agent  118  creates an explosion-tight seal between the luminaire enclosure lens  112  and the luminaire enclosure cover  106 . This explosion-tight seal disallows flames or hot gasses likely to ignite a flame or cause an explosion, from exiting the luminaire enclosure  102  between the luminaire enclosure lens  112  and the luminaire enclosure cover  106 . The luminaire enclosure cover  106 , the encapsulating gasket  108 , and an explosion protected luminaire enclosure lens  112 , are secured to one another, and fastened to the luminaire enclosure backing  104  via one or more enclosure fasteners (not shown). In this way, the luminaire enclosure cover  106 , when fastened to the luminaire enclosure backing  104  according to the methods and products described herein, creates an explosion encapsulating luminaire enclosure  102 . In some embodiments, the encapsulating gasket is secured to the luminaire enclosure backing  104  or is free-floating. 
     In most embodiments, the luminaire enclosure lens  112  is generally planar in shape, but it is contemplated that the luminaire enclosure lens  112  may take other shapes and that other configurations may be used. In embodiments where the luminaire enclosure lens  112  is non-planar, the luminaire enclosure lens  112  may still be qualified for use in environments containing explosive gases or under an explosion encapsulating protective standard. Additionally, the luminaire enclosure lens  112  can be plain or it can have optical features (e.g. frosting, textured surface, prisms, etc.) that alter or condition light emitted from a visible light emitter, such as LED arrays  120 . The luminaire enclosure lens  112  can also be used to address color mixing or color angle concerns. 
     In the embodiment shown, a plurality of LED arrays  120  is arranged on a pcb board  122 . A plurality of LED protective lens arrays  124  are secured to the luminaire enclosure backing  104 , through the pcb board  122 . The LED protective lens arrays  124  are positioned over each of the LED arrays  120  and secured to the pcb board  122 . Luminaire enclosure lens  112  is positioned at a distance from the LED protective lens arrays  124  and pcb board  122 . In the embodiments shown, a spacer portion  127  of the assembled luminaire enclosure  102  defines a luminaire cavity  128  between the LED protective lens arrays  124  and the luminaire enclosure lens  112  by mechanically preventing the movement of the luminaire enclosure lens  112  and the pcb board  122  toward one another within the luminaire enclosure  102 . In fabricating the luminaire enclosure  102 , the volume of the luminaire cavity  128  may be strategically determined based on a particular explosion encapsulating protective standard. For example, if the Ex d protection standard is applied, the volume of the luminaire cavity  128  is minimized when fabricating the luminaire enclosure  102 . For example, to adhere to a particular explosion encapsulating standard, the dimensions of the luminaire enclosure cover and the luminaire enclosure backing may be chosen so that the height of the luminaire cavity (i.e., the distance between the luminaire lens and the luminaire enclosure backing) is between 5 mm and 100 mm. Minimizing the volume of the luminaire cavity  128  while adhering to flame path and gap requirements helps to reduce the required reference pressure that the luminaire enclosure  102  must withstand during an overpressure test used in qualification of an enclosure under the Ex d protection standard, in particular. In addition to helping to encapsulate an internal explosion, the luminaire enclosure lens  112  prevents transmission of any flame, resulting from an explosion within the luminaire enclosure  102 , to the exterior of the luminaire enclosure  102 . In this way, the luminaire cavity  128  provides a secondary internalized burn out path for any ignited flammable gas within the luminaire enclosure  102 . More broadly, the luminaire cavity  128  provides additional space for ignited explosive or flammable gas ignited under the LED protective lens arrays  124  to burn out without any flames or hot gas (e.g. likely to ignite an external flammable or explosive gas) from reaching the exterior of the luminaire enclosure  102  without cooling first. 
     In the embodiment shown, the luminaire enclosure backing  104  comprises a heat conductive material and acts as a heatsink for the pcb board  122  which may heat up during operation. The luminaire enclosure backing  104  acts as a mounting surface for the pcb board  122  and may conduct heat to the luminaire enclosure backing  104  via the mechanical fasteners  126  or via surface contacts or heat pipes. In some embodiments, the entire luminaire enclosure  102  may be comprised of a lightweight, heat-conductive metal such as aluminum or titanium. In this way, the entire luminaire enclosure may be used as a heatsink for the LED arrays  120  and the pcb board  122  during operation of the luminaire system  100 . In some embodiments, only certain parts, such as limited portions of the luminaire enclosure backing  104  and luminaire enclosure cover  106  comprise a heat-conductive material. In such embodiments, those certain parts may be used as localized heatsinks. 
     In the embodiment shown, the luminaire system  100  includes a controls enclosure  132  that encloses a lighting gearbox  134  and an LED driver  136 . Here, the controls enclosure  132  is also qualified to encapsulate an explosion occurring within the controls enclosure  132 . That is, the controls enclosure  132  comprises a controls enclosure backing  138  and controls enclosure cover  139  that, when secured together, yield a seal that prevents flames or hot gasses inside the controls enclosure  132  from reaching the outside of the controls enclosure  132  (e.g. Ex d protection qualified). In the embodiment shown, the controls enclosure  132  removably connects to the luminaire enclosure  102  via an adaptor  140 . In some embodiments, the adaptor  140  connects the controls enclosure  132  to the luminaire enclosure  102  via electrical contacts. In other embodiments, the adaptor  140  connects the controls enclosure  132  to the luminaire enclosure  102  wirelessly. In still other embodiments, the adaptor  140  connects the controls enclosure  132  to the luminaire enclosure  102  via a removable or fixed wired connection. In the embodiments wherein electrical wires of contacts run through the adaptor  140 , the adaptor is also qualified to encapsulate an explosion, via adaptor gasket  141 , so that an explosion, flames, or hot gases will not be transmitted from the luminaire enclosure  102  to the controls enclosure  132 , or vice versa without cooling first. 
     In the embodiment shown, the lighting gearbox  134  is configured to perform analog regulation of an electrical input from a power source (not shown) and output a regulated electrical signal to the LED driver  136 . The LED driver  136  delivers an electrical signal to the LED arrays  120  based upon the regulated electrical signal received from the lighting gearbox  134 , causing the LED arrays  120  to emit light. 
     One or more mounting components  142  may be disposed on one or more portions of the luminaire enclosure  102 . The mounting components  142  may be configured to secure the luminaire enclosure  102  to a rod, a cord, a chain, or any other known component or assembly for attaching a luminaire to a surface or hanging it therefrom. The mounting components  142  may also be configured to connect the luminaire enclosure  102  to a pole, post, ceiling, or other structure. Mounting components  142  may also include brackets having a pair of openings that receive fasteners to fasten the luminaire enclosure  102  to a wall. Similar mounting components can also be used to secure the controls enclosure  132  to a surface. 
     The LED driver  136  may be disposed in the luminaire enclosure  102  or in the controls enclosure  132 . Similarly, lighting gearbox  134  may be disposed in the luminaire enclosure  102  or in the controls enclosure  132 . A power supply  146  may provide power to the luminaire enclosure  102  or controls enclosure  132  and in turn the pcb board  122 , the LED driver  136  and the LED arrays  120 . The LED driver  136  provides a power signal to the LED arrays  120 , causing them to emit light. The power supply  146  may be any combination of drivers, ballasts, or other power supply depending on the type of LEDs in the LED arrays  120 . The LED driver  136  can be a separate component or can be integrated with a light engine on the same circuit board as the LED arrays  120 . For example, the power supply  146  may be a power signal corrector including components such as a voltage regulator or bridge rectifier. Additionally, the power supply  146  may be an onboard or externally connected battery. In certain aspects, the luminaire enclosure can be connected to power supply  146  or connected directly to line power (not shown). 
     One or more control components  148 , may be connected to or integrated with the luminaire system  100 . The control components  148  can include backup battery units, fuses, microprocessors, FPGAs, surge protectors, wired or wireless communication modules (e.g., CAT5, radio, Wi-Fi, etc.), sensors (e.g., light, occupancy, motion, heat, temperature, etc.), or any combination thereof. In some embodiments, the control components  148  include components facilitating the connection of the luminaire system  100  to a network that includes other luminaire controllers and one or more controllers for distributed communication and centralized control of the luminaire system  100 . 
     Certain embodiments utilize reflectors, baffles, louvers or other optical features to direct light through the luminaire enclosure lens  112  during operation of the luminaire system  100 .  FIG. 1  shows an embodiment of a luminaire system wo illustrated as a linear luminaire. LED arrays  120  are positioned in the luminaire enclosure  102  and configured to emit visible light directly through the luminaire enclosure lens  112 . However, in other embodiments, reflectors, louvers, fiber optics, or baffles may be used to transmit light emitted by the LED arrays  120  through the luminaire enclosure lens  112  indirectly. 
       FIG. 2  illustrates a front view of the luminaire system  100 ,  200 . Enclosure fasteners  230  are positioned along the perimeter of the luminaire enclosure cover  206 . The even spacing of enclosure fasteners  230  may help ensure a seal against the luminaire enclosure backing  104  that retains hot flue gases or flames after an internal explosion. Mechanical fasteners  226  secure the pcb board  222 , and LED protective lens arrays  124 ,  224  to the luminaire enclosure backing  104 , thereby creating a flame-tight seal between the luminaire enclosure backing  104  and luminaire enclosure cover  106  via encapsulating gasket  108 . The mechanical fasteners  226  also ensure that an outer flame path  247  is disposed between the luminaire cavity  128  and the encapsulating gasket  108 . As with other flame paths, the outer flame path  247  allows flames to suffocate and hot gasses to cool as they travel through the flame path. In the case of the outer flame path  247 , the flames or hot gasses are cooled before they reach the exterior of the luminaire enclosure  102 ,  202 , specifically. 
       FIG. 3  illustrates a closeup view of LED protective lens arrays  324  within the luminaire enclosure  202  is shown. A plurality of LED arrays  320  is configured to emit light directly through the LED protective lens arrays  324  and luminaire enclosure lens  112 ,  212 , when powered. In the embodiment shown, the LED protective lens arrays  324  are tightly secured in over the LED arrays  320 , creating a mechanical seal that disallows a flame or hot gas from travelling into or out of any of the protective lenses  352  within LED protective lens arrays  324  before cooling. In some embodiments, the LED protective lens arrays  324  are cemented into place with a sealing agent (not shown) that aids in making each of the LED protective lens arrays  324  explosion encapsulating. For example, the sealing agent may be a silicone sealant adhesive, but may include other sealing agents. In some embodiments, an explosion retaining LED protective lens array gasket (not shown) may be used in conjunction with the LED protective lens arrays  324 . In such cases, the LED protective lens arrays  324  may be pressed down onto the LED protective lens array gasket, thereby creating the aforementioned mechanical, flame and hot gas encapsulating seal. That is, during assembly of the luminaire system  100 , the underside of the LED protective lens arrays  324  are positioned over the pcb board  322  and fastened to the luminaire enclosure backing  104 ,  204 , through the LED protective lens arrays  324  and the pcb board  322  using mechanical fasteners  326 . 
     In the embodiment shown, the LED protective lens array  324  includes eight LED protective lenses  356  in a rectangular configuration. Each LED protective lens  356  includes an LED accommodating cavity  358 . The LED protective lens array  324  also includes a center aperture  360  configured to receive the mechanical fastener  326 . Accordingly, the LED protective lens array  324  is configured to be attached to the pcb board  222  by way of mechanical fasteners  126  interacting with the pcb board  222  via the center aperture  360 . The LED accommodating cavities are  358  are configured to overlay and protect the individual LED elements  323  of the LED arrays  120  when the LED protective lens array  324  is placed onto the pcb board  222 . 
     In the embodiment shown, the LED protective lens arrays  324  can be fastened to the luminaire enclosure backing  304  to create sufficient pressure between the LED protective lens arrays  324  and the pcb board  322  creating a sufficiently resistive flame paths (not shown) under the LED protective lens arrays  324 . The flame paths and mitigate the effects of a flame igniting within one of the LED protective lens arrays  324  on items exterior to the LED protective lens arrays  324 . Additionally, in some embodiments, an LED protective lens array clamp plate (not shown) can be positioned over the LED protective lens arrays  324  and fastened to the luminaire enclosure backing  304  thereby sandwiching the LED protective lens arrays between the LED protective lens array clamp plate and the pcb board  322  and creating even more pressure on the flame path. 
       FIG. 4  illustrates a luminaire enclosure cover  406  including an encapsulating gasket  408  a luminaire enclosure lens  412  and an enclosure fastener  430 . The luminaire enclosure cover  406  is configured to ensure that the luminaire enclosure  202 , is explosion encapsulating when secured to the luminaire enclosure backing  104  according to the methods and products described herein. For example, the sealing agent  418  cements the luminaire enclosure lens  412  into the lens accommodating window  214  of the luminaire enclosure cover  406 . The sealing agent  418  may be explosion-tight, and thereby create an explosion encapsulating seal between the luminaire enclosure lens  412  and the luminaire enclosure cover  406  that disallows flames or hot gasses from exiting the luminaire enclosure  102 ,  202  between the luminaire enclosure lens  412  and the luminaire enclosure cover  406 . Similarly, in some embodiments, the encapsulating gasket  408  is explosion-tight. In embodiments wherein the luminaire enclosure cover  106  is explosion-tight, and the luminaire enclosure cover  106  is explosion-tight and comprises an explosion-tight encapsulating gasket  408  the entire luminaire enclosure  202  becomes explosion encapsulating when fastened together by the enclosure fasteners  430 . 
     In a number of embodiments, the encapsulating gasket  108  may not aid in encapsulating an explosion and in some embodiments may not be present. For example, in some embodiments, the encapsulating gasket may be configured primarily to prevent the ingress of dust or liquid into the luminaire enclosure  102 . As another example, the encapsulating gasket  108  may be excluded from the luminaire enclosure  102  because, for a particular use of the luminaire system  100 , there may be no need to prevent the ingress of dust or liquid into the luminaire enclosure  102 . 
     In some embodiments, the luminaire enclosure lens  412  is held in or to the luminaire enclosure  202  in manners not shown. For example, in some embodiments, the sealing agent  418  cementing the luminaire enclosure lens  412  in or to the luminaire enclosure cover  406  can be replaced by mechanical fasteners, welds, etc. Similarly, in some embodiments, mechanical fasteners and enclosure fasteners may be replaced by adhesives, welds, etc. 
     In some embodiments, a heatsink  150  can be positioned in or on the luminaire enclosure  202  and draw heat from the LED arrays  320 , during operation. However, in most cases, the luminaire enclosure  202 , is constructed of a heatsinking material such as a heat conductive metal, and the luminaire enclosure  102  itself may therefore act as a heatsink for the LED arrays  120 , during operation. It is also contemplated that same embodiments do not include a heat sink. 
       FIGS. 5 a , 5 b , and 5 c    illustrate a LED protective lens array  524  including four LED protective lenses  556  in a 2×2 configuration. Each LED protective lens  556  includes an LED accommodating cavity  558 . the LED protective lens array  524 , and includes a center aperture  560  configured to receive the mechanical fastener  226 . The LED protective lens array  524  also includes, at its corners, fastener accommodating cutouts  562  configured to be engaged by a mechanical fastener  126 . The LED protective lens array  524  is configured to be attached to the pcb board  222  by way of mechanical fasteners  126  interacting with the pcb board  222  via at least one of the center aperture  560  and the fastener accommodating cutouts  562 . The LED accommodating cavities are  558  are configured to overlay and protect the individual LED elements  323  of the LED arrays  120  when the LED protective lens array  524  is placed onto the pcb board  222 . 
       FIG. 5 d    illustrates a cross-section  562  of an embodiment of the led protective lens  556 . In the embodiment shown, the LED accommodating cavity  558  includes plurality of inner walls  564  forming tiered, concentric, conical cavities of differing slopes, diameters, and heights. In the embodiment shown, the outermost wall of the plurality of inner walls  564  has a diameter of 6.7 millimeters and a height of 0.84 millimeters; a second wall, just above the outermost wall, has a diameter of 6.37 millimeters and rises 0.64 millimeters above the outermost wall; a third wall, just above the second wall has a diameter of 3.97 millimeters and rises 1 millimeter above the second wall; lastly, a final wall, just above the third wall, rises 0.21 millimeters above the third wall, has a diameter of 2.06 millimeters, and comes to a closed, conical apex in the center of the LED accommodating cavity  558 . 
       FIGS. 6 a  and 6 b    illustrate a perspective view and a top view, respectively, of the luminaire system  600  including a luminaire enclosure  602 . Enclosure fasteners  630  (screws, in the embodiment shown) are positioned along the perimeter edge of the luminaire enclosure cover  606 . The even spacing of enclosure fasteners  630  help ensure a, explosion protected seal including at least one flame path  247  is formed between the luminaire enclosure cover  606  and the luminaire enclosure backing  604 . Additionally, adaptors  664   a ,  664   b  provide channels for an exterior power or data source (not shown) to communicate electronically with a control board (not shown) of the luminaire  602  or with the pcb board  122 . For example, a controls enclosure  232  may be configured to communicate with the luminaire  602  via the adaptors  664   a ,  664   b  and control the LED arrays  620  or the individual LED elements  623 . The luminaire  602  also includes a standalone battery indicator light  668  configured to indicate a condition of the battery (e.g., a low charge condition, a charged condition, a damaged condition). As will be discussed in further detail below, a standalone flame protected LED optic houses the standalone battery indicator light  668  and provides flame protection for the standalone battery indicator light  668 . 
     In the embodiment shown, a mounting surface  615  of the luminaire enclosure backing  604  is visible through the lens accommodating widow  614  of the luminaire enclosure cover  606 . The mounting surface comprises a plurality of mechanical fastener engaging cavities  616  configured to receive mechanical fasteners  326  for fixing the protective LED lens arrays  524  to the pcb board  122 , and the pcb board  122  and protective LED lens arrays  524  to the mounting surface  615  of the luminaire enclosure backing  604 . The volume of the luminaire cavity  128  is determined to prioritize the flame and hot gas protection described herein by reducing the internal pressure that can potentially be caused by an explosion in the luminaire cavity  128 . Accordingly, the volume of the luminaire cavity  128  is minimized when fabricating the luminaire enclosure  602  so that an explosion occurring in the luminaire cavity  628  is accordingly contained with less effort than would be required if luminaire cavity  628  was relatively large. 
     Although not shown in  FIGS. 6 a  and 6 b   , the luminaire  602  may include a hollow compartment disposed on a backside of the luminaire enclosure backing  604 . The hollow compartment may contain mounting equipment configured to mount the luminaire enclosure backing  604  (and thereby the luminaire  602 ) to a surface (e.g., a wall, a ceiling, a doorway). The hollow compartment may also be used for storage of electronic components (e.g., a battery, a controls circuit). 
       FIGS. 7 a  and 7 b    illustrate a perspective view and a top view, respectively, of another luminaire system  700  including a luminaire enclosure  702 . Enclosure fasteners  730  (screws, in the embodiment shown) are positioned along the perimeter edge of the luminaire enclosure cover  706 . As with the luminaire  602  shown in  FIG. 6 a   , the even spacing of enclosure fasteners  730  help ensure an explosion protected seal of the luminaire enclosure cover  706  against the luminaire enclosure backing  704 . Mechanical fasteners  726  fix the LED protective lens arrays  724  over the pcb board  722  by mechanically engaging the luminaire enclosure backing  704  through the pcb board  722 . In the embodiment shown, a plurality of LED arrays  720  is configured to emit light through the luminaire lens  712 . Additionally, aperture  770  provides a way for an exterior power or data source (not shown) to communicate electronically with a control board (not shown) of the luminaire  702  or with the pcb board  722 , as described above, with respect to  FIG. 6 . As with the luminaire of  FIGS. 6 a  and 6 b   , the luminaire  702  includes a standalone battery indicator light  768  configured to indicate a condition of the battery (e.g., a low charge condition, a charged condition, a damaged condition). Additionally, aperture  770  is configured to maintain the explosion protected status of the luminaire  702  by forming a flame and hot gas seal against the materials inserted therein (e.g., wires, a plug). 
       FIGS. 8 a  and 8 b    illustrate a standalone battery indicator light lens  874 . The standalone battery indicator light lens  874  comprises an indicator light cavity  876  configured to receive a standalone battery indicator light  768  and to provide explosion protection of the type described herein for the standalone battery indicator light  768  when fixed to the pcb board  722 . 
     In some embodiments, the LED protective lens arrays  324  are not present. In such embodiments, the luminaire enclosure  202  may still be explosion-encapsulating and encapsulate any explosion occurring within the luminaire enclosure  202 . 
     The foregoing detailed description of the certain exemplary embodiments has been provided for the purpose of explaining the general principles and practical application, thereby enabling others skilled in the art to understand the disclosure for various embodiments and with various modifications as are suited to the particular use contemplated. This description is not necessarily intended to be exhaustive or to limit the disclosure to the exemplary embodiments disclosed. Modifications may be made to adapt a particular situation or material to the teachings of the disclosure without departing from the scope thereof. Any of the embodiments and/or elements disclosed herein may be combined with one another to form various additional embodiments not specifically disclosed. Accordingly, additional embodiments are possible and are intended to be encompassed within this specification and the scope of the appended claims. The specification describes specific examples to accomplish a more general goal that may be accomplished in another way. 
     As used in this application, the terms “front,” “rear,” “upper,” “lower,” “upwardly,” “downwardly,” and other orientational descriptors are intended to facilitate the description of the exemplary embodiments of the present application, and are not intended to limit the structure of the exemplary embodiments of the present application to any particular position or orientation. Terms of degree, such as “substantially” or “approximately” are understood by those of ordinary skill to refer to reasonable ranges outside of the given value, for example, general tolerances associated with manufacturing, assembly, and use of the described embodiments.