Intrinsically safe apparatus

Abstract

An intrinsically safe apparatus is disclosed. The intrinsically safe apparatus includes a power source. The intrinsically safe apparatus further includes a first component configured to be electrically powered by the power source. The intrinsically safe apparatus further includes a first electrical path between the power source and the first component. The intrinsically safe apparatus further includes a mechanical fuse electrically connected to the first electrical path. The mechanical fuse is configured to interrupt current flow above a first current level. The intrinsically safe apparatus further includes an electronic fuse electrically connected to the first electrical path. The electronic fuse is electrically connected in series between the first component and the mechanical fuse. The electronic fuse is configured to interrupt current flow above a second current level. The second current level is less than the first current level.

Description

[0001] PA102376W002

[0002] INTRINSICALLY SAFE APPARATUS

[0003] Technical Field

[0004] The present disclosure relates generally to an intrinsically safe apparatus.

[0005] Background

[0006] An apparatus, such as a personal protective equipment apparatus, may be used by personnel (e.g., emergency responders) working in hazardous environments (e.g., an explosive environment). The apparatus may include various electronic and electrical components, for example, to generate telemetry data, alerts, etc., and / or communicate the same with other personnel or a central base station. The electronic and electrical components of the apparatus may be powered by one or more power sources.

[0007] To operate safely in the hazardous environments, the apparatus may need to be designed in compliance with certain intrinsic safety standards, such that the apparatus does not generate a spark or undergo a thermal event even under fault conditions. The intrinsic safety standards may require the apparatus to include fuses, which may need to be replaced once operated (e.g., blown). However, replacing such fuses of the apparatus after each occurrence of a fault condition may be expensive, time consuming, require excessive diagnosis, and increase a downtime of the apparatus.

[0008] Summary

[0009] In one aspect, the present disclosure provides an intrinsically safe apparatus. The intrinsically safe apparatus includes at least one power source. The intrinsically safe apparatus further includes at least one first component configured to be electrically powered by the at least one power source. The intrinsically safe apparatus further includes a first electrical path between the at least one power source and the at least one first component. The intrinsically safe apparatus further includes a mechanical fuse electrically connected to the first electrical path. The mechanical fuse is configured to interrupt current flow above a first current level. The intrinsically safe apparatus further includes an electronic fuse electrically connected to the first electrical path. The electronic fuse is electrically connected in series between the at least one first component and the mechanical fuse. The electronic fuse is configured to interrupt current flow above a second current level. The second current level is less than the first current level.

[0010] The details of one or more examples of the disclosure are set forth in the accompanying drawings and the description below. Other features, objects, and advantages of the disclosure will be apparent from the description and drawings, and from the claims.

[0011] Brief Description of Drawings

[0012] Exemplary embodiments disclosed herein are more completely understood in consideration of the following detailed description in connection with the following figures. The figures are not necessarily drawn to scale. Like numbers used in the figures refer to like components. However, it will be understood that the use of a number to refer to a component in a given figure is not intended to limit the component in another figure labelled with the same number.

[0013] FIG. 1 is a schematic perspective view of an intrinsically safe apparatus according to an embodiment of the present disclosure;

[0014] FIG. 2 is a schematic circuit diagram of the intrinsically safe apparatus according to an embodiment of the present disclosure;

[0015] FIG. 3 is a schematic circuit diagram of an intrinsically safe apparatus according to another embodiment of the present disclosure;

[0016] FIG. 4 is a schematic circuit diagram of an intrinsically safe apparatus according to another embodiment of the present disclosure; and

[0017] FIG. 5 is a schematic circuit diagram of an intrinsically safe apparatus according to another embodiment of the present disclosure.

[0018] Detailed Description

[0019] In the following description, reference is made to the accompanying figures that form a part thereof and in which various embodiments are shown by way of illustration. It is to be understood that other embodiments are contemplated and may be made without departing from the scope or spirit of the present disclosure. The following detailed description, therefore, is not to be taken in a limiting sense.

[0020] In the following disclosure, the following definitions are adopted.

[0021] As used herein, “a,” “an,” “the,” “at least one,” and “one or more” are used interchangeably. As used herein as a modifier to a property or attribute, the term “generally,” unless otherwise specifically defined, means that the property or attribute would be readily recognizable by a person of ordinary skill but without requiring absolute precision or a perfect match (e.g., within + / - 20 % for quantifiable properties).

[0022] The term “substantially,” unless otherwise specifically defined, means to a high degree of approximation (e.g., within + / - 10% for quantifiable properties) but again without requiring absolute precision or a perfect match.

[0023] As used herein, all numbers should be considered modified by the term “about.” The term “about,” unless otherwise specifically defined, means to a high degree of approximation (e.g., within + / - 5% for quantifiable properties) but again without requiring absolute precision or a perfect match.

[0024] As used herein, the terms “first” and “second” are used as identifiers. Therefore, such terms should not be construed as limiting of this disclosure. The terms “first” and “second” when used in conjunction with a feature or an element can be interchanged throughout the embodiments of this disclosure.

[0025] As used herein, “at least one of A and B” should be understood to mean “only A, only B, or both A and B.”

[0026] As used herein, the term “between about,” unless otherwise specifically defined, generally refers to an inclusive or a closed range. For example, if a parameter X is between about A and B, then A < X < B.

[0027] As used herein, the term “hazardous or potentially hazardous environments” may refer to environments that include hazardous or potentially hazardous environmental conditions. The hazardous or potentially hazardous environments may include, for example, explosive environments, chemical environments, biological environments, nuclear environments, fires, industrial sites, construction sites, agricultural sites, mining sites, or manufacturing sites.

[0028] As used herein, the term “electrical path” refers to a path that is configured to carry or provide an electrical signal, a current, or a voltage. An electrical path may be formed by various different types of electrical conductors, such as wires, traces, etc.

[0029] The present disclosure relates to an intrinsically safe apparatus. The intrinsically safe apparatus includes at least one power source. The intrinsically safe apparatus further includes at least one first component configured to be electrically powered by the at least one power source. The intrinsically safe apparatus further includes a first electrical path between the at least one power source and the at least one first component. The intrinsically safe apparatus further includes a mechanical fuse electrically connected to the first electrical path. The mechanical fuse is configured to interrupt current flow above a first current level. The intrinsically safe apparatus further includes an electronic fuse electrically connected to the first electrical path. The electronic fuse is electrically connected in series between the at least one first component and the mechanical fuse. The electronic fuse is configured to interrupt current flow above a second current level. The second current level is less than the first current level.

[0030] The intrinsically safe apparatus may protect the mechanical fuse under certain fault conditions due to which the current flowing through the first electrical path may rise above the second current level. For example, the electronic fuse may interrupt current flow to the first component in case of a fault condition between the first component and the electronic fuse (e.g., a short at the first component or shorting of wires connected to the first component) before the mechanical fuse operates (i.e., interrupts current flow), thereby preventing the mechanical fuse from operating and protecting the mechanical fuse. The electronic fuse may allow current flow to the first component once the fault condition is rectified, for example, once the current flowing through the first electrical path becomes lower than the second current level.

[0031] As a result, the intrinsically safe apparatus may meet regulatory requirements for intrinsic safety (e.g., the mechanical fuse being in an operational condition) while protecting the mechanical fuse under the fault condition. Once the fault condition is rectified, the intrinsically safe apparatus may operate normally without needing to replace the mechanical fuse, the electronic fuse, or any module of the intrinsically safe apparatus including the mechanical fuse and / or the electronic fuse.

[0032] Referring now to the figures, FIG. 1 illustrates a schematic perspective view of an intrinsically safe apparatus 100 (hereinafter also referred to as “the apparatus 100”) according to an embodiment of the present disclosure.

[0033] The apparatus 100, being intrinsically safe, may be used by a user (not shown) in an environment, such as a hazardous or potentially hazardous environment. The user of the apparatus 100 may be any emergency personnel, such as a firefighter, a first responder, a healthcare professional, a paramedic, a hazardous materials (HAZMAT) removal worker, security personnel, law enforcement personnel, or any other personnel working in the environment. If the user is a firefighter, the apparatus 100 may be worn by the firefighter in the environment.

[0034] In the illustrated embodiment of FIG. 1, the apparatus 100 is a self-contained breathing apparatus (SCBA). Specifically, the apparatus 100 may include an air cylinder 12 containing breathable air. The breathable air may include pressurized breathable air. The apparatus 100 may further include a back frame 14 configured to support the air cylinder 12 on a back of the user. The air cylinder 12 may be mounted on the back frame 14. The back frame 14 may include shoulder straps 15 and a belt 16, that are wearable by the user.

[0035] The apparatus 100 may further include a facemask 18 arranged to provide the breathable air from the air cylinder 12 to the user. The apparatus 100 may further include a regulator 20 in fluid communication with the air cylinder 12 and configured to control a supply of the breathable air to the facemask 18. The regulator 20 may be configured to control the supply of the breathable air to the facemask 18. The apparatus 100 may further include an air line / data line 22, which may supply the breathable air from the air cylinder 12 to the regulator 20 and provide data communications and power supply to the regulator 20.

[0036] The apparatus 100 may further include an electronic module 26 (schematically depicted by a block in FIG. 1). The electronic module 26 may include one or more components (not shown). The one or more components of the electronic module 26 may include one or more processors, one or more sensors, one or more communication devices, and so forth. The one or more processors may include any suitable data processor for processing data. For example, the one or more processors may include a microprocessor, a microcontroller, a computer, or other suitable devices that control operation of devices and execute programs. Various other examples of the one or more processors include central processing units (“CPUs”), microcontrollers, programmable logic devices, field programmable gate arrays, digital signal processing (“DSP”) devices, and the like. The one or more processors may include any general variety device such as a reduced instruction set computing (“RISC”) device, a complex instruction set computing (“CISC”) device, or a specially designed processing device, such as an application specific integrated circuit (“ASIC”) device.

[0037] The apparatus 100 includes at least one power source 102 (hereinafter also referred to as “the power source 102”). The power source 102 may be configured to power one or more components of the apparatus 100. For example, the one or more components of the electronic module 26 may be electrically connected to the power source 102 to receive power supply from the power source 102. The power source 102 may include one or more electrochemical cells of any suitable type. In some embodiments, the power source 102 may include one or more lithium-based cells. The one or more lithium-based cells may be based on lithium chemistry, such as lithium-air, lithium-ion, and lithium-polymer, and so forth.

[0038] The electronic module 26 may be mounted on the back frame 14. Alternatively, the electronic module 26 may be disposed at any other location on the apparatus 100, for example, on any one of the shoulder straps 15. The air line / data line 22 may be communicably and / or electrically coupled to the one or more components of the electronic module 26. The air line / data line 22 may further be electrically connected to the power source 102 to provide power from the power source 102 to the regulator 20.

[0039] The apparatus 100 may further include a headgear (not shown) to provide protection to the head of the user. The headgear may include one or more electronic components communicably and / or electrically connected to the one or more components of the electronic module 26. The headgear may include safety goggles, a safety hat, or combinations thereof. The headgear may further include a heads-up display (HUD). The HUD may display one or more parameters of the apparatus 100 to the user. The one or more parameters may include parameters associated with a state of health of the apparatus 100, parameters associated with the environment of the apparatus 100, or a combination thereof. The HUD may display a notification including instructions and / or information received from a command gateway (not shown), and / or from other portable devices (not shown). The headgear may further include a hearing device (not shown). In some examples, the hearing device may include a wired / wireless headphone and / or an earphone communicably and / or electrically coupled to the electronic module 26. In some other examples, the hearing device may include a hearing protection device, such as, a pair of earmuffs. The air line / data line 22 may provide data communications and power supply to the HUD via the electronic module 26 and the power source 102, respectively.

[0040] The apparatus 100 may further include a personal alert safety system (PASS) device 30. The PASS device 30 may include a PASS control console 32 and an alert unit 34. The PASS control console 32 may hang from an end of a pressure data line 36, connected via a pressure reducer (not shown) to the air cylinder 12, and a cable sheath 40. The alert unit 34 may be carried in a recess in the back frame 14. The apparatus 100 may further include a personal digital assistance (PDA) device 38. The PDA device 38 may be located on the PASS device 30. In some embodiments, the PASS device 30 may be communicably and / or electrically connected to electronic module 26 and powered by the power source 102. The cable sheath 40 may carry electronic cables that connect the electronic module 26 and the PASS device 30.

[0041] FIG. 2 illustrates a schematic circuit diagram of the apparatus 100 according to an embodiment of the present disclosure.

[0042] As discussed above, the apparatus 100 includes the power source 102. The apparatus 100 further includes at least one first component 104 (hereinafter also referred to as “the first component 104”). The first component 104 is configured to be electrically powered by the power source 102. The first component 104 may be any component of the apparatus 100 that is designed to be electrically powered by the power source 102. For example, referring to FIGS. 1 and 2, the first component 104 may include the one or more components of the electronic module 26, the regulator 20, the PASS device 30, and so forth. In some embodiments, the first component 104 may include an alert device, a gauge, or a display device . The display device may include the HUD described above with reference to FIG. 1. In some embodiments, the alert device may include the PASS device 30 (shown in FIG. 1) or a distress signaling device.

[0043] The apparatus 100 further includes a first electrical path 106 between the power source 102 and the first component 104. The first component 104 may receive electrical power from the power source 102 via the first electrical path 106.

[0044] The apparatus 100 further includes a mechanical fuse 108 electrically connected to the first electrical path 106. The mechanical fuse 108 may be electrically disposed in the first electrical path 106. The mechanical fuse 108 may form a portion of the first electrical path 106. The mechanical fuse 108 is configured to interrupt current flow above a first current level. Specifically, the mechanical fuse 108 may be configured to intermpt current flow to the first component 104 above the first current level. The mechanical fuse 108 may interrupt current flow from the power source 102 to the first component 104 when the current flowing through the first electrical path 106 reaches or becomes greater than the first current level. The first current level may correspond to a fuse point of the mechanical fuse 108.

[0045] The mechanical fuse 108 may include, for example, a wire strip that melts when a current above the first current level flows through it. If a current above the first current level flows through the mechanical fuse 108, the mechanical fuse 108 “operates” or “blows”, i.e., intermpts the first electrical path 106. The mechanical fuse 108 may be sacrificial. That is, once the mechanical fuse 108 operates, it may need to be replaced with a new one. However, due to various design and compliance restrictions, the mechanical fuse 108 may be non- replaceable. More specifically, the mechanical fuse 108 may not be independently replaceable. The apparatus 100 may include a module (e.g., the electronic module 26 of FIG. 1 or a printed circuit board) including the mechanical fuse 108. In order to replace the mechanical fuse 108, the entire module may need to be replaced.

[0046] The apparatus 100 further includes an electronic fuse 110 electrically connected to the first electrical path 106. The electronic fuse 110 is electrically connected in series between the first component 104 and the mechanical fuse 108. The electronic fuse 110 may be electrically disposed in the first electrical path 106 between the first component 104 and the mechanical fuse 108. The electronic fuse 110 may form a portion of the first electrical path 106. The electronic fuse 110 is configured to interrupt current flow above a second current level. Specifically, the electronic fuse 110 may be configured to interrupt current flow to the first component 104 above the second current level. The electronic fuse 110 may interrupt current flow from the power source 102 to the first component 104 when the current flowing through the first electrical path 106 reaches or becomes greater than the second current level. The second current level may correspond to a current trip point of the electronic fuse 110.

[0047] The electronic fuse 110 may include an input terminal and an output terminal that together form a portion of the first electrical path 106, and a switching element (such as a Metal Oxide Semiconductor Field Effect Transistor (MOSFET) or an Insulated-Gate Bipolar Transistor (IGBT)) configured to selectively enable and disable current flow between the input terminal and the output terminal. The switching element of the electronic fuse 110 may allow current flow through the electronic fuse 110 when the current flowing through the first electrical path 106 remains below the second current level. The switching element of the electronic fuse 110 may interrupt and disallow current flow through the electronic fuse 110 when the current flowing through the first electrical path 106 reaches or remains above the second current level. As compared to the mechanical fuse 108, the electronic fuse 110 may not need replacement after operation (i.e., after interrupting current flow).

[0048] The second current level is less than the first current level. In other words, the current trip point of the electronic fuse 110 may be lower than the fuse point of the mechanical fuse 108. The current trip point of the electronic fuse 110 may be selected such that the electronic fuse 110 can handle the maximum load requirement of the first component 104 (and other components of the apparatus 100 not shown in FIG. 2), but does not exceed the fuse point of the mechanical fuse 108. Therefore, the electronic fuse 110 may interrupt current flow to the first component 104 at a lower current level than the mechanical fuse 108.

[0049] The apparatus 100 may protect the mechanical fuse 108 under certain fault conditions due to which the current flowing through the first electrical path 106 may rise above the second current level. For example, the electronic fuse 110 may interrupt current flow to the first component 104 in case of a fault condition between the first component 104 and the electronic fuse 110 (e.g., a short at the first component 104 or shorting of wires connected to the first component 104) before the mechanical fuse 108 operates (i.e., intermpts current flow), thereby preventing the mechanical fuse 108 from operating and protecting the mechanical fuse 108. The electronic fuse 110 may allow current flow to the first component 104 once the fault condition is rectified, for example, once the current flowing through the first electrical path 106 becomes lower than the second current level. As a result, the apparatus 100 may meet regulatory requirements for intrinsic safety (e.g., the mechanical fuse 108 being in an operational condition) while protecting the mechanical fuse 108 under the fault condition. Once the fault condition is rectified, the apparatus 100 may operate normally without needing to replace the mechanical fuse 108, the electronic fuse 110, or any module of the apparatus 100 including the mechanical fuse 108 and / or the electronic fuse 110.

[0050] In some embodiments, the apparatus 100 may further include a controller 112 configured to detect a fault condition. The fault condition may be indicative of interruption of current flow by at least one of the mechanical fuse 108 and the electronic fuse 110. Specifically, the fault condition may be indicative of interruption of current flow to the first component 104 by at least one of the mechanical fuse 108 and the electronic fuse 110.

[0051] For example, the controller 112 may be electrically connected to the first electrical path 106 and configured to monitor a flow of current from the power source 102 to the first component 104 in order to detect the fault condition. In some examples, the controller 112 may be configured to monitor the flow of current at different points of the first electrical path 106 to determine the cause of the fault condition. In some examples, the controller 112 may be a master control unit (e.g., PASS MCU).

[0052] In some embodiments, the apparatus 100 may further include an indicator 114 communicably coupled to the controller 112. The controller 112 may be configured to indicate the fault condition via the indicator 114 upon detection of the fault condition. In some embodiments, the indicator 114 may include a visual indicator, an audible indicator, a tactile indicator, or combinations thereof. Examples of the visual indicator include displays, light indicators, etc. Examples of the audible indicator include headphones, speakers, bone conduction devices, etc. Examples of the tactile indicator include force feedback devices, electro-stimulation devices, and other tactile sensory stimulation devices. It may be noted that the controller 112 and the indicator 114 may be powered by the power source 102 or by a different power source. The controller 112 and the indicator 114 may facilitate detection and diagnosis of the fault condition.

[0053] FIG. 3 illustrates a schematic circuit diagram of an intrinsically safe apparatus 200 (hereinafter also referred to as “the apparatus 200”) according to another embodiment of the present disclosure. The apparatus 200 is similar to the apparatus 100 of FIG. 2, with like elements designated by like reference characters. However, the apparatus 200 has a configuration for interfacing with battery packs. Specifically, in the illustrated embodiment of FIG. 3, the apparatus 200 further includes a battery pack 116 including the power source 102. The apparatus 200 further includes a battery pack interface 118 configured to removably receive the battery pack 116 and electrically connect the power source 102 to the first component 104. The battery pack interface 118 may include an electrical connector (not shown) that forms a portion of the first electrical path 106 between the power source 102 and the first component 104. Further, in some embodiments, the battery pack 116 may include the mechanical fuse 108. The battery pack 116 may include a battery circuit (not shown) connected to the power source 102 and including the mechanical fuse 108. The battery circuit may form a portion of the first electrical path 106.

[0054] The apparatus 200, or more specifically, the electronic fuse 110 may protect the mechanical fuse 108 of the battery pack 116 in case of the fault condition. Without the electronic fuse 110, if the fault condition occurs, the mechanical fuse 108 of the battery pack 116 may operate, thereby rendering the battery pack 116 unusable (since the mechanical fuse 108 can operate only once). In contrast, due to the electronic fuse 110, the mechanical fuse 108 of the battery pack 116 may remain protected (i.e., the mechanical fuse 108 may not operate) even under the fault condition. Consequently, the battery pack 116 may remain operational under the fault condition. This may allow the battery pack 116 to be used with another unit of the apparatus 200 or used again with the apparatus 200 once the fault condition is rectified.

[0055] FIG. 4 illustrates a schematic circuit diagram of an intrinsically safe apparatus 300 (hereinafter also referred to as “the apparatus 300”) according to another embodiment of the present disclosure. The apparatus 300 is similar to the apparatus 100 of FIG. 2, with like elements designated by like reference characters. However, the apparatus 300 includes additional components as compared to the apparatus 100.

[0056] Specifically, in the illustrated embodiment of FIG. 4, the apparatus 300 further includes at least one second component 304 (hereinafter also referred to as “the second component 304”) configured to be electrically powered by the power source 102. The second component 304 may be any component of the apparatus 300 that is designed to be electrically powered by the power source 102.

[0057] In some embodiments, the second component 304 may include an alert device, an audible alarm unit, a telemetry radio, an audio-video indicator, a data logging device, or a controller of the apparatus 300. In some embodiments, the alert device may include the PASS device 30 (shown in FIG. 1) or a distress signaling device. The second component 304 may be different from the first component 104. For example, if the first component 104 includes the PASS device 30, the second component 304 may be any component of the apparatus 300 other than the PASS device 30 (e.g., the one or more components of the electronic module 26 of FIG. 1). It may be desired that the second component 304 remains functional even if a fault condition occurs due to the first component 104.

[0058] The apparatus 300 may further include a node 302 electrically disposed in the first electrical path 106 between the mechanical fuse 108 and the electronic fuse 110. The second component 304 may be electrically connected to the node 302. The apparatus 300 may further include a second electrical path 306 between the node 302 and the second component 304. This configuration may allow the second component 304 to continue receiving power from the power source 102 and function normally even if the electronic fuse 110 interrupts current flow to the first component 104.

[0059] In some embodiments, the apparatus 300 may further include a current-limiting resistor 308 electrically connected in series with the mechanical fuse 108. In some embodiments, the current-limiting resistor 308 may be electrically disposed between the mechanical fuse 108 and the first component 104. In the illustrated embodiment of FIG. 4, the current-limiting resistor 308 is electrically disposed between the mechanical fuse 108 and the node 302. The currentlimiting resistor 308 may be designed to limit the flow of current to a predetermined value, based on the first component 104 and / or the second component 304.

[0060] FIG. 5 illustrates a schematic circuit diagram of an intrinsically safe apparatus 400 (hereinafter also referred to as “the apparatus 400”) according to another embodiment of the present disclosure. The apparatus 400 is similar to the apparatus 300 of FIG. 4, with like elements designated by like reference characters. However, the apparatus 400 includes additional components as compared to the apparatus 300.

[0061] Specifically, in the illustrated embodiment of FIG. 5, the apparatus 400 further includes a printed circuit board 402. The printed circuit board 402 may include at least one conductive trace 404 (hereinafter also referred to as “the conductive trace 404”) at least partially forming the first electrical path 106. The conductive trace 404 is depicted with a dashed line in FIG. 5. The printed circuit board 402 may further include at least one second conductive trace 405 (hereinafter also referred to as “the second conductive trace 405”) at least partially forming the second electrical path 306. The second conductive trace 405 is also depicted with a dashed line in FIG. 5.

[0062] The mechanical fuse 108 and the electronic fuse 110 may be electrically connected to the conductive trace 404. Further, the current-limiting resistor 308 may be electrically connected to the conductive trace 404. In some embodiments, the mechanical fuse 108 and the electronic fuse 110 may be non-replaceable. For example, the mechanical fuse 108 and the electronic fuse 110 may be non-removably connected (e.g., via soldering) to the conductive trace 404 and the printed circuit board 402.

[0063] In some embodiments, the apparatus 400 may further include a wire conduit 410 (e.g., the cable sheath 40 of FIG. 1) configured to receive at least one wire 408. The at least one wire 408 may electrically connect the conductive trace 404 to the first component 104. In some embodiments, the at least one wire 408 may include a plurality of wires 408, such that the wire conduit 410 contains or covers the plurality of wires 408. The fault condition may occur due to a shorting of the plurality of wires 408. The electronic fuse 110 may protect the mechanical fuse 108 under such fault condition. As a result, the printed circuit board 402 may not need to be replaced due to such fault condition.

[0064] Unless otherwise indicated, all numbers expressing feature sizes, amounts, and physical properties used in the specification and claims are to be understood as being modified by the term “about”. Accordingly, unless indicated to the contrary, the numerical parameters set forth in the foregoing specification and attached claims are approximations that can vary depending upon the desired properties sought to be obtained by those skilled in the art utilizing the teachings disclosed herein.

[0065] Although specific embodiments have been illustrated and described herein, it will be appreciated by those of ordinary skill in the art that a variety of alternate and / or equivalent implementations can be substituted for the specific embodiments shown and described without departing from the scope of the present disclosure. This application is intended to cover any adaptations or variations of the specific embodiments discussed herein. Therefore, it is intended that this disclosure be limited only by the claims and the equivalents thereof.

Claims

CLAIMSWhat is claimed is:

1. An intrinsically safe apparatus comprising: at least one power source; at least one first component configured to be electrically powered by the at least one power source; a first electrical path between the at least one power source and the at least one first component; a mechanical fuse electrically connected to the first electrical path, wherein the mechanical fuse is configured to interrupt current flow above a first current level; and an electronic fuse electrically connected to the first electrical path, wherein the electronic fuse is electrically connected in series between the at least one first component and the mechanical fuse, wherein the electronic fuse is configured to interrupt current flow above a second current level, and wherein the second current level is less than the first current level.

2. The intrinsically safe apparatus of claim 1, further comprising: a node electrically disposed in the first electrical path between the mechanical fuse and the electronic fuse; and at least one second component configured to be electrically powered by the at least one power source, wherein the at least one second component is electrically connected to the node.

3. The intrinsically safe apparatus of claim 2, further comprising a second electrical path between the node and the at least one second component.

4. The intrinsically safe apparatus of claim 2, wherein the at least one second component comprises an alert device, an audible alarm unit, a telemetry radio, an audio-video indicator, a data logging device, or a controller of the intrinsically safe apparatus.

5. The intrinsically safe apparatus of claim 1, wherein the at least one first component comprises an alert device, a gauge, or a display device.

6. The intrinsically safe apparatus of claim 5, wherein the alert device comprises a personal alert safety system (PASS) device or a distress signaling device.

7. The intrinsically safe apparatus of claim 1, further comprising: a battery pack comprising the at least one power source; and a battery pack interface configured to removably receive the battery pack and electrically connect the at least one power source to the at least one first component.

8. The intrinsically safe apparatus of claim 7, wherein the battery pack comprises the mechanical fuse.

9. The intrinsically safe apparatus of claim 1, further comprising: a controller configured to detect a fault condition, wherein the fault condition is indicative of interruption of current flow by at least one of the mechanical fuse and the electronic fuse; and an indicator communicably coupled to the controller, wherein the controller is configured to indicate the fault condition via the indicator upon detection of the fault condition.

10. The intrinsically safe apparatus of claim 9, wherein the indicator comprises a visual indicator, an audible indicator, a tactile indicator, or combinations thereof.

11. The intrinsically safe apparatus of claim 1, further comprising a printed circuit board, the printed circuit board comprising at least one conductive trace at least partially forming the first electrical path, wherein the mechanical fuse and the electronic fuse are electrically connected to the at least one conductive trace.

12. The intrinsically safe apparatus of claim 11, further comprising a wire conduit configured to receive at least one wire, wherein the at least one wire electrically connects the at least one conductive trace to the at least one first component.

13. The intrinsically safe apparatus of claim 1 , further comprising a current-limiting resistor (CLR) electrically connected in series with the mechanical fuse.

14. The intrinsically safe apparatus of claim 1, wherein the at least one power source comprises one or more lithium-based cells.

15. The intrinsically safe apparatus of claim 1, wherein the mechanical fuse and the electronic fuse are non-replaceable.

16. The intrinsically safe apparatus of claim 1, wherein the intrinsically safe apparatus is a self-contained breathing apparatus (SCBA).

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