Monitoring aerosol density levels in fire sensing devices

Abstract

Devices, methods, and systems for monitoring aerosol density levels in self-testing fire sensing devices are described herein. In one embodiment, an apparatus includes an adjustable particle generator configured to generate an aerosol; an optical scattering chamber configured to measure an aerosol density level of the aerosol; and a controller configured to compare the measured aerosol density level to a threshold aerosol density level and to cause the adjustable particle generator to stop generating the aerosol in response to the measured aerosol density level reaching and remaining at or above the threshold aerosol density level for a specific period of time.

Description

Technical Field

[0001] The present disclosure generally relates to devices, methods, and systems for monitoring aerosol density levels in fire sensing devices. Background Art

[0002] Large facilities (e.g., buildings), such as commercial facilities, office buildings, hospitals, etc., may have fire alarm systems that can be triggered during an emergency (e.g., a fire) to warn occupants to evacuate. For example, a fire alarm system may include a fire control panel and multiple fire sensing devices (e.g., smoke detectors) throughout the facility (e.g., on different floors and / or in different rooms of the facility) that can sense a fire occurring in the facility and provide notification of the fire to occupants of the facility via an alarm.

[0003] Maintenance of fire alarm systems may include mandatory periodic testing of fire sensing devices in accordance with operating procedures in an attempt to ensure that the fire sensing devices are functioning properly. However, since testing can only be done periodically, there is a risk that a faulty fire sensing device may not be discovered quickly or that all fire sensing devices in the fire alarm system will not be tested.

[0004] Typical testing involves a maintenance engineer using a pressurized aerosol to force synthetic smoke into the chamber of the fire sensing device, which saturates the chamber. In some examples, the maintenance engineer may also use a heat gun to increase the temperature of a thermal sensor in the fire sensing device and / or a gas generator to exhaust carbon monoxide (CO) gas into the fire sensing device. These tests may not accurately mimic the characteristics of a fire, and therefore, these tests may not accurately determine the ability of the fire sensing device to detect an actual fire.

[0005] Moreover, this process of manually testing each fire sensing device can be time consuming, expensive, and disruptive to business. For example, maintenance engineers are often required to access fire sensing devices located in areas occupied by building users or in generally inaccessible parts of a building (e.g., elevator shafts, high ceilings, ceiling spaces, etc.). As a result, it may take several days and several visits for maintenance engineers to complete testing of fire sensing devices, especially in large locations. Additionally, there are often many fire sensing devices that are never tested due to access issues.

[0006] Over time, the fire sensing device may become dirty, for example, with dust and debris, and become clogged. A clogged fire sensing device may prevent air and / or particles from passing through the fire sensing device to a sensor in the fire sensing device, which may otherwise render the fire sensing device unable to detect smoke, fire, and / or carbon monoxide. BRIEF DESCRIPTION OF THE DRAWINGS

[0007] Figure 1 A block diagram illustrating a self-test function of a fire sensing device according to an embodiment of the present disclosure.

[0008] Figure 2 A portion of an example of a self-testing fire sensing device according to an embodiment of the present disclosure is shown.

[0009] Figure 3 An example of a self-testing fire sensing device according to an embodiment of the present disclosure is shown.

[0010] Figure 4 A block diagram illustrating the self-test functionality of a system according to an embodiment of the present disclosure is shown.

[0011] Figure 5 A plot is shown of an example optical scattering chamber output for determining when a measured aerosol density level reaches a threshold aerosol density level in a moderate ambient air flow environment, according to an embodiment of the present disclosure.

[0012] Figure 6 A plot is shown of an example optical scattering chamber output for determining when a measured aerosol density level reaches a threshold aerosol density level in a high ambient air flow environment in accordance with an embodiment of the present disclosure.

[0013] Figure 7 A plot is shown of an example optical scattering chamber output for determining when a measured aerosol density level reaches a threshold aerosol density level in a low ambient air flow environment in accordance with an embodiment of the present disclosure. DETAILED DESCRIPTION

[0014] Devices, methods, and systems for monitoring aerosol density levels in a self-testing fire sensing device are described herein. A device includes: an adjustable particle generator configured to generate an aerosol; an optical scattering chamber configured to measure an aerosol density level of the aerosol; and a controller configured to compare the measured aerosol density level to a threshold aerosol density level and to stop the adjustable particle generator from generating aerosol in response to the measured aerosol density level reaching and remaining at or above the threshold aerosol density level for a specific period of time.

[0015] Previous fire sensing devices in which wax and / or liquid are heated to a specific temperature and / or heated for a specific amount of time to generate an aerosol for testing the functionality of the device may produce too little aerosol or too much aerosol due to environmental factors including temperature, air flow, sensor orientation, pressure and / or relative humidity and / or due to manufacturing fluctuations in coil resistance, number of coil turns, wire type and / or initial liquid or wax amount, and other manufacturing fluctuations. In contrast, fire sensing devices according to the present disclosure are able to produce a more controlled amount of aerosol by stopping the generation of aerosol when the measured aerosol density level reaches a threshold aerosol density level. Therefore, fire sensing devices according to the present disclosure may use less liquid and / or wax to generate aerosol, have lower visible contaminant rates per test, have reduced wax contamination accumulation rates, have manufacturing variables compensated, operational variables compensated, environmental variables compensated and / or have better tolerances than previous devices.

[0016] In the following Detailed Description, reference is made to the accompanying drawings which form part of the present Detailed Description. The drawings show, by way of illustration, the manner in which one or more embodiments of the present disclosure may be practiced.

[0017] These embodiments are described in sufficient detail to enable one of ordinary skill in the art to practice one or more embodiments of the present disclosure. It should be understood that other embodiments may be utilized and mechanical, electrical and / or process changes may be made without departing from the scope of the present disclosure.

[0018] It should be understood that the elements shown in the various embodiments herein may be added, exchanged, combined and / or eliminated to provide multiple additional embodiments of the present disclosure. The proportions and relative sizes of the elements provided in the drawings are intended to illustrate embodiments of the present disclosure and should not be limiting.

[0019] The figures herein follow the following numbering convention: one or more first digits correspond to the figure number, and the remaining digits identify the element or component in the figure. Similar elements or components between different figures may be identified by using similar numerals. For example, 104 may refer to Figure 1 Element "04" in , and Figure 2 Similar elements in can be referenced as 204.

[0020] As used herein, "a" or "a number of" things may refer to one or more such things, and "a number of" things may refer to more than one such things. For example, "a number of components" may refer to one or more components, and "a number of components" may refer to more than one component.

[0021] Figure 1A block diagram of a self-test function of a fire sensing device 100 (e.g., the fire sensing device 100 may be a self-testing fire sensing device) according to an embodiment of the present disclosure is shown. The fire sensing device 100 includes a controller (e.g., a microcontroller) 122, an adjustable particle generator 102, an optical scattering chamber 104, and a variable airflow generator 116.

[0022] The controller 122 may include a memory 124 and a processor 126. The memory 124 may be any type of storage medium that can be accessed by the processor 126 to perform various examples of the present disclosure. For example, the memory 124 may be a non-transitory computer-readable medium having computer-readable instructions (e.g., computer program instructions) stored thereon, which instructions may be executed by the processor 126 to monitor the aerosol density level in the fire sensing device 100 according to the present disclosure. For example, the processor 126 may execute executable instructions stored in the memory 124 to compare the measured aerosol density level with a threshold aerosol density level, and in response to the measured aerosol density level reaching and remaining at or above the threshold aerosol density level for a specific period of time, the adjustable particle generator 102 stops generating aerosol. In some examples, the memory 124 may store the measured aerosol density level, the threshold aerosol density level, and / or the baseline aerosol density level.

[0023] In various embodiments, the controller 122 may send commands to the adjustable particle generator 102 to generate particles (aerosol particles). Aerosol particles may be solid particles or liquid particles in a gas. The particles generated by the adjustable particle generator 102 may be moved (e.g., drawn) through the optical scattering chamber 104 by the variable airflow generator 116, generating an air flow and producing a controlled aerosol density level. The threshold aerosol density level may be sufficient to trigger a fire response of the fire sensing device 100 without saturating the optical scattering chamber 104. For example, the threshold aerosol density level may be 0.2 to 1.0 decibels per meter (dB / m). Figure 1 As shown, the optical scattering chamber 104 may include a transmitter light emitting diode (LED) 105 and a receiver photodiode 106 to measure aerosol density levels.

[0024] In response to the measured aerosol density level reaching and remaining at or above the threshold aerosol density level for a specific period of time, the variable airflow generator 116 may continue to generate the airflow to reduce the aerosol density level within the fire sensing device 100. The optical scattering chamber 104 may measure the additional aerosol density level while the variable airflow generator 116 continues to generate the airflow. The controller 122 may compare the additional measured aerosol density level with the baseline aerosol density level. The controller 122 may stop the variable airflow generator 116 from generating the airflow after a specific period of time or in response to the additional measured aerosol density level reaching the baseline aerosol density level.

[0025] In some examples, in response to causing adjustable particle generator 102 to stop generating aerosol, additional aerosol density levels of the aerosol may be measured in optical scattering chamber 104, and variable airflow generator 116 may be stopped from generating air flow in response to the additional measured aerosol density levels decreasing to the baseline aerosol density level.

[0026] The variable airflow generator 116 may continue to generate the airflow in response to the additional measured aerosol density levels being above the baseline aerosol density level. The additional aerosol density levels may be measured in the optical scattering chamber 104, and the variable airflow generator 116 may be stopped in response to one or more of the measured additional aerosol density levels decreasing to the baseline aerosol density level.

[0027] In some examples, the adjustable particle generator 102 may continue to generate aerosol for a specific amount of time while the measured aerosol density level remains at or above the threshold aerosol density level. For example, the adjustable particle generator 102 may stop generating aerosol one second after the measured aerosol density level reaches the threshold aerosol density level.

[0028] The adjustable particle generator 102 may continue to generate aerosol, and the optical scattering chamber 104 may continue to measure the aerosol density level until the measured aerosol density level reaches (e.g., increases to) a threshold aerosol density level. For example, the adjustable particle generator 102 may generate aerosol in response to the measured aerosol density level being below the threshold aerosol density level. Additional aerosol density levels of the aerosol in the optical scattering chamber 104 may be measured, and the adjustable particle generator 102 may stop generating aerosol in response to one or more of the measured additional aerosol density levels increasing to the threshold aerosol density level. If the aerosol density level within the fire sensing device 100 fails to reach the threshold aerosol density level and / or the baseline aerosol density level, a message may be transmitted.

[0029] Figure 2A portion of an example of a self-testing fire sensing device 200 according to an embodiment of the present disclosure is shown. The fire sensing device 200 may be, but is not limited to, a fire detector and / or a smoke detector of a fire control system.

[0030] The fire sensing device 200 can sense a fire occurring in a facility and trigger a fire response to provide notification of the fire to the occupants of the facility. The fire response can include, for example, a visual and / or audio alarm. The fire response can also notify emergency services (e.g., fire department, police department, etc.). In some examples, multiple fire sensing devices can be located throughout the facility (e.g., on different floors and / or in different rooms of the facility).

[0031] The fire sensing device 200 may automatically or upon command conduct one or more tests contained within the fire sensing device 200. The one or more tests may determine whether the fire sensing device 200 is functioning properly and / or requires maintenance.

[0032] like Figure 2 As shown, the fire sensing device 200 may include an optical scattering chamber 204 and a variable airflow generator 216, which may correspond to Figure 1 The optical scattering chamber 104 and the variable airflow generator 116. The additional flame sensing device 200 may also include a controller and a similar Figure 1 In addition, the functions of the optical scattering chamber 204 and the variable airflow generator 216 can be similar to those described herein. Figure 3 The functions of chamber 304 and variable airflow generator 316 are further described.

[0033] Figure 3 FIG. 3 shows an example of a self-testing fire sensing device 300 according to an embodiment of the present disclosure. The fire sensing device 300 may be, but is not limited to, a fire detector and / or a smoke detector of a fire control system. The fire sensing device 300 may correspond to Figure 1 or Figure 2 The fire sensing device 100 or the fire sensing device 200 in.

[0034] The fire sensing device 300 may automatically or upon command perform one or more tests contained within the fire sensing device 300. The one or more tests may determine whether the fire sensing device 300 is functioning properly and / or requires maintenance.

[0035] like Figure 3As shown, the fire sensing device 300 may include an adjustable particle generator 302, an optical scattering chamber 304 including a transmitter light emitting diode (LED) 305 and a receiver photodiode 306, a heat source 308, a reservoir 312, and a variable airflow generator 316. In some examples, the fire sensing device 300 may also include a controller including a memory and / or a processor, as previously described in conjunction with Figure 1 described.

[0036] The heat source 308 of the adjustable particle generator 302 can heat the liquid and / or wax contained in the reservoir 312 to generate aerosol particles, which can be mixed into a controlled aerosol density level by the variable airflow generator 316. The heat source 308 can be, for example, a resistance wire coil. The current flowing through the resistance wire coil can be used to control the temperature of the heat source 308 and further control the number of particles generated by the adjustable particle generator 302. The heat source 308 can heat the liquid and / or wax to form airborne particles to simulate smoke from a fire. The particles can measure a diameter of about 1 micron and / or the particles can be within the sensitivity range of the optical scattering chamber 304. The heat source 308 can heat the liquid and / or wax until the aerosol density level reaches a threshold aerosol density level; the heat source 308 can stop heating the liquid and / or wax in response to the aerosol density level reaching and remaining at or above the threshold aerosol density level for a specific period of time. The threshold aerosol density level may be an aerosol density level sufficient to trigger a fire response from a properly functioning fire sensing device without saturating the optical scattering chamber 304 and / or an aerosol density level sufficient to test a fault condition without triggering a fire response or saturating the optical scattering chamber 304 .

[0037] The variable airflow generator 316 can control the airflow through the first sensing device 300 including the optical scattering chamber 304. For example, the variable airflow generator 316 can move the gas and / or aerosol from the first end of the fire sensing device 300 to the second end of the fire sensing device 300. In some examples, the variable airflow generator 316 can be a fan. The variable airflow generator 316 can be activated in response to the adjustable particle generator 302 being activated, or the variable airflow generator 316 can be activated for a specific period of time after the adjustable particle generator 302 has been activated. The variable airflow generator 316 can be stopped in response to the adjustable particle generator 302 being stopped and / or the variable airflow generator 316 can be stopped for a specific period of time after the adjustable particle generator 302 has been stopped.

[0038] In various embodiments, once the measured aerosol density level has reached a threshold aerosol density level, the adjustable particle generator 316 may be turned off and the variable airflow generator 316 may increase the rate of air flow through the optical scattering chamber 304. The variable airflow generator 316 may increase the rate of air flow through the optical scattering chamber 304 to reduce the aerosol density level back to a baseline level. The baseline level may be the initial level of the optical scattering chamber 304 before the adjustable particle generator 302 generates particles. For example, the variable airflow generator 316 may remove aerosol in the optical scattering chamber 304 after the measured aerosol density level reaches a threshold aerosol density level. If the fire sensing device 300 is not blocked or covered, the airflow from the external environment through the optical scattering chamber 304 will cause the aerosol density level to decrease. Since the damper opening in the fire sensing device 300 allows air and / or smoke from the fire to flow through the fire sensing device 300, the optical scattering chamber 304 may sense the external environment.

[0039] As previously described, if the device does not reach the threshold aerosol density level, the fire sensing device 300 may generate a message. The fire sensing device 300 may send the message to, for example, a monitoring device and / or a mobile device. As an additional example, the fire sensing device 300 may include a user interface that may display the message.

[0040] Figure 4 A block diagram of a self-test function of a system 420 according to an embodiment of the present disclosure is shown. The system 420 may include a fire sensing device 400, a monitoring device 401, and a computing device 430. The fire sensing device 400 may be, for example, a previously described fire sensing device 400, a monitoring device 401, and a computing device 430. Figure 1 , Figure 2 and Figure 3 The fire sensing device 100, 200 and / or 300.

[0041] The fire sensing device 400 may include a user interface 440. The user interface 440 may be a graphical user interface (GUI) that may provide information to and / or receive information from a user, the monitoring device 401, and / or the computing device 430. In some examples, the user interface 440 may display a message. For example, a message may be displayed in response to a measured aerosol density level failing to increase to a threshold aerosol density level and / or an additional measured aerosol density level failing to decrease to a baseline aerosol density level.

[0042] The monitoring device 401 may be a cloud computing device of a control panel, a fire detection control system, and / or a fire alarm system. The monitoring device 401 may be configured to send commands to the fire sensing device 400 and / or receive messages from the fire sensing device via a wired or wireless network. For example, the fire sensing device 400 may transmit (e.g., send) a message to the monitoring device 401 in response to the measured aerosol density level failing to increase to the threshold aerosol density level and / or the additional measured aerosol density level failing to decrease to the baseline aerosol density level.

[0043] The monitoring device 401 may receive messages from a plurality of fire sensing devices similar to the fire sensing device 400. For example, the monitoring device 401 may receive a message from each of a plurality of fire sensing devices similar to the fire sensing device 400, and create a maintenance schedule based on the message from each of the plurality of fire sensing devices.

[0044] In various embodiments, the monitoring device 401 may include a user interface 436. The user interface 436 may be a GUI that may provide information to and / or receive information from a user and / or the fire sensing device 400. The user interface 436 may display messages and / or data received from the fire sensing device 400. For example, the user interface 436 may display a message that the fire sensing device 400 requires maintenance.

[0045] In various embodiments, the computing device 430 may receive messages from the fire sensing device 400 and / or the monitoring device 401 via a wired or wireless network. The computing device 430 may be a personal laptop computer, a desktop computer, a mobile device (such as a smart phone, a tablet computer, a wrist-worn device), and / or redundant combinations thereof, as well as other types of computing devices.

[0046] In some examples, the computing device 430 may include a user interface 438 to display messages from the monitoring device 401 and / or the fire sensing device 400. For example, the user interface 438 may display messages. The user interface 438 may be a GUI that may provide information to and / or receive information from a user, the monitoring device 401, and / or the fire sensing device 400.

[0047] The network described herein may be a network relationship through which the fire sensing device 400, the monitoring device 401, and / or the computing device 430 can communicate with each other. Examples of such network relationships may include a distributed computing environment (e.g., a cloud computing environment), a wide area network (WAN) such as the Internet, a local area network (LAN), a personal area network (PAN), a campus area network (CAN), or a metropolitan area network (MAN), as well as other types of network relationships. For example, the network may include a plurality of servers that receive information from the fire sensing device 400, the monitoring device 401, and the computing device 430 via a wired or wireless network and transmit information to the fire sensing device, the monitoring device, and the computing device.

[0048] As used herein, a "network" may provide a communication system that directly or indirectly links two or more computers and / or peripheral devices and allows the monitoring device 401 and / or computing device 430 to access data and / or resources on the fire sensing device 400 or vice versa. A network may allow a user to share resources on their own system with other network users and access information on a system located in a central location or a system located in a remote location. For example, a network may connect multiple computing devices together to form a distributed control network (e.g., a cloud).

[0049] The network may provide connectivity to the Internet and / or to the networks of other entities (e.g., organizations, institutions, etc.). Users may interact with network-enabled software applications to make network requests, such as to obtain data. Applications may also communicate with network management software, which may interact with network hardware to transfer information between devices on the network.

[0050] Figure 5 A plot (e.g., graph) 550 of an example optical scattering chamber output (e.g., aerosol density level measurements) is shown for determining when a measured aerosol density level 582 reaches a threshold aerosol density level 556 in a moderate ambient air flow environment in accordance with an embodiment of the present disclosure.

[0051] exist Figure 5 In the example shown in FIG. 1 , a heat source (e.g., a variable airflow generator (e.g., variable airflow generator 116, 216, or 316 described previously herein) and an adjustable particle generator (e.g., adjustable particle generator 102 or 302 described previously herein) are provided. Figure 3 The heat source 308 in FIG. 5 may be de-energized (eg, turned off) at time 552-1, as indicated by Figure 5 584 and heat level 586 shown in FIG. At time 552-2, the heat source may be energized (eg, turned on) to heat the wax and / or liquid to generate particles (eg, aerosol particles), as previously described in conjunction with Figure 1 and Figure 3 described.

[0052] At time 552-3, the variable airflow generator may be turned on. When turned on, the variable airflow generator (e.g., a fan) may generate an airflow, as indicated by airflow level 584, to mix the generated particles into a controlled aerosol density level and move the generated particles through an optical scattering chamber (e.g., optical scattering chamber 104, 204, or 304 previously described herein). The optical scattering chamber may determine a measured aerosol density level 582 over time. Figure 5 As shown, after the variable air flow generator is turned on and causes the air flow within the fire sensing device to increase, the measured aerosol density level 582 begins to increase.

[0053] The heat source may continue to provide heat to generate particles until a threshold aerosol density level (e.g., a set point) 556 is reached. For example, the threshold aerosol density level 556 may be an aerosol density level sufficient to trigger a properly functioning fire sensing device to initiate a fire response (e.g., a fire threshold) without saturating the optical scattering chamber.

[0054] Based on including Figure 5 It may take more or less time for the measured aerosol density level 582 to reach the threshold aerosol density level 556 due to environmental factors including the air flow, temperature, sensor orientation, pressure, and / or relative humidity shown, and / or due to manufacturing fluctuations in coil resistance, number of coil turns, wire type, and / or initial liquid or wax amount, and other manufacturing fluctuations. Figure 5 The measured aerosol density level 582 over time shown in FIG. 5 may be derived from a fire sensing device experiencing a moderate ambient air flow, and in combination with Figure 6 The measured aerosol density levels described over time (e.g., measured aerosol density levels 682) may be from a fire sensing device experiencing high ambient air flow, and combined with Figure 7 The measured aerosol density levels depicted over time (eg, measured aerosol density levels 782 ) may be from a fire sensing device experiencing low ambient air flow.

[0055] In some examples, fire sensing devices experiencing low ambient air temperatures may take longer to reach the threshold aerosol density level 556 than fire sensing devices experiencing moderate ambient air temperatures because it takes longer to heat wax and / or liquids in a colder environment. Similarly, fire sensing devices experiencing moderate ambient air temperatures may take longer to reach the threshold aerosol density level 556 than fire sensing devices experiencing high ambient air temperatures.

[0056] The fire sensing device according to the present disclosure may generate a more controlled amount of aerosol by stopping the generation of aerosol when the measured aerosol density level 582 reaches the threshold aerosol density level 556 instead of stopping the generation of aerosol after a specific period of time and / or after reaching a specific temperature. Thus, the fire sensing device according to the present disclosure may use less liquid and / or wax to generate aerosol, have a lower visible contaminant rate per test, have a reduced wax contamination accumulation rate, have manufacturing variables compensated, operational variables compensated, environmental variables compensated, and / or have a specified tolerance with better pass / fail criteria than previous fire sensing devices.

[0057] Once the threshold aerosol density level 556 is reached, or once the measured aerosol density level 582 has been above the threshold aerosol density level 556 for a period of time, the heat source can be turned off and the adjustable particle generator can stop generating particles at time 552-4. Figure 5 As shown, the variable air flow generator may continue and / or increase the air flow 584 to move the generated particles out of the optical scattering chamber.

[0058] After the heat source has been turned off, the measured aerosol density level 582 may decrease over time, such as Figure 5 For example, the measured aerosol density level 582 may decrease to or below the baseline aerosol density level 554. In various embodiments, once the measured aerosol density level 582 reaches the baseline aerosol density level 554 or after the measured aerosol density level 582 has been below the baseline aerosol density level 554 for a period of time, the variable airflow generator may be turned off at time 552-5.

[0059] Figure 6 A plot (e.g., graph) 660 of example optical scattering chamber output (e.g., aerosol density level measurements) for determining when a measured aerosol density level 682 reaches a threshold aerosol density level 656 in a high ambient air flow environment is shown according to an embodiment of the present disclosure. A high ambient air flow environment may be created, for example, by the proximity of a fire sensing device to a fan, vent, or door.

[0060] exist Figure 6 In the example shown in FIG. 1 , a heat source (e.g., a variable airflow generator (e.g., variable airflow generator 116, 216, or 316 described previously herein) and an adjustable particle generator (e.g., adjustable particle generator 102 or 302 described previously herein) are provided. Figure 3 The heat source 308 in FIG. 60 may be de-energized (eg, turned off) at time 662-1, as indicated by Figure 6At time 662-2, the heat source may be energized (eg, turned on) to heat the wax and / or liquid to generate particles (eg, aerosol particles), as previously described in conjunction with Figure 1 and Figure 3 described.

[0061] At time 662-3, the variable airflow generator may be turned on. When turned on, the variable airflow generator (e.g., a fan) may generate an airflow, as indicated by airflow level 684, to mix the generated particles into a controlled aerosol density level and move the generated particles through an optical scattering chamber (e.g., optical scattering chamber 104, 204, or 304 previously described herein). The optical scattering chamber may determine a measured aerosol density level 682 over time. Figure 6 As shown, after the variable flow generator is turned on, the measured aerosol density level 682 begins to increase.

[0062] The heat source may continue to provide heat to generate particles until a threshold aerosol density level (eg, a set point) 656 is reached. The threshold aerosol density level 656 may correspond to Figure 5 The threshold aerosol density level in 556.

[0063] Based on including Figure 6 Depending on environmental factors and / or manufacturing fluctuations including the air flow shown, it may take more or less time for the measured aerosol density level 682 to reach the threshold aerosol density level 656. Figure 5 The fire sensing device of the present figure, which experiences high ambient air flow, may take longer to reach the threshold aerosol density level 656 compared to the fire sensing device of FIG.

[0064] Once the threshold aerosol density level 656 is reached, or once the measured aerosol density level 682 has been above the threshold aerosol density level 656 for a period of time, the heat source can be turned off and the adjustable particle generator can stop generating particles at time 662-4. Figure 6 As shown, the variable air flow generator may continue and / or increase the air flow 684 to move the generated particles out of the optical scattering chamber.

[0065] After the heat source has been turned off, the measured aerosol density level 682 may decrease over time, such as Figure 6 For example, the measured aerosol density level 682 may decrease to or below the baseline aerosol density level 654, which may correspond to Figure 5In various embodiments, once the measured aerosol density level 682 reaches the baseline aerosol density level 654 or after the measured aerosol density level 682 has been at or below the baseline aerosol density level 654 for a period of time, the variable airflow generator can be turned off at time 662-5.

[0066] Figure 7 A plot (e.g., graph) 770 of an example optical scattering chamber output (e.g., aerosol density level measurements) for determining when a measured aerosol density level 782 reaches a threshold aerosol density level 756 in a low ambient air flow environment is shown according to an embodiment of the present disclosure. A low ambient air flow environment may be due to, for example, a fire sensing device being shielded. For example, a fire sensing device may be shielded when the fire sensing device is covered or blocked, which may impede or prevent air flow and / or particles from entering and / or leaving the fire sensing device.

[0067] exist Figure 7 In the example shown in FIG. 1 , a heat source (e.g., a variable airflow generator (e.g., variable airflow generator 116, 216, or 316 described previously herein) and an adjustable particle generator (e.g., adjustable particle generator 102 or 302 described previously herein) are provided. Figure 3 The heat source 308 in the embodiment may be de-energized (eg, turned off) at time 772-1, as indicated by Figure 7 At time 772-2, the heat source may be energized (eg, turned on) to heat the wax and / or liquid to generate particles (eg, aerosol particles), as previously described in conjunction with Figure 1 and Figure 3 described.

[0068] At time 772-3, the variable airflow generator may be turned on. When turned on, the variable airflow generator (e.g., a fan) may generate an airflow, as indicated by airflow level 784, to mix the generated particles into a controlled aerosol density level and move the generated particles through an optical scattering chamber (e.g., optical scattering chamber 104, 204, or 304 previously described herein). The optical scattering chamber may determine a measured aerosol density level 782 over time. Figure 7 As shown, after the variable flow generator is turned on, the measured aerosol density level 782 begins to increase.

[0069] The heat source may continue to provide heat 786 to generate particles until a threshold aerosol density level (eg, a set point) 756 is reached. The threshold aerosol density level 756 may correspond to Figure 5 Threshold aerosol density level 556 and / or Figure 6The threshold aerosol density level in 656.

[0070] Based on including Figure 7 Depending on environmental factors and / or manufacturing fluctuations including the air flow shown, it may take more or less time for the measured aerosol density level 782 to reach the threshold aerosol density level 756. Figure 5 Fire sensing equipment or that experiences high ambient air flow Figure 6 The fire sensing device of the present figure experiencing low ambient air flow may take less time to reach the threshold aerosol density level 756 compared to the fire sensing device of FIG.

[0071] Once the threshold aerosol density level 756 is reached, or once the measured aerosol density level 782 has been above the threshold aerosol density level 756 for a period of time, the heat source can be turned off and the adjustable particle generator can stop generating particles at time 772-4. Figure 7 As shown, the variable air flow generator may continue and / or increase the air flow 784 to move the generated particles out of the optical scattering chamber.

[0072] After the heat source has been turned off, the measured aerosol density level 782 may decrease over time. For example, the measured aerosol density level 782 may decrease to or below the baseline aerosol density level 754, which may correspond to Figure 5 The reference aerosol density level discussed in 554 or Figure 6 In various embodiments, once the measured aerosol density level 782 reaches the baseline aerosol density level 754 or after the measured aerosol density level 782 has been at or below the baseline aerosol density level 754 for a period of time, the variable airflow generator can be turned off.

[0073] exist Figure 7 In the example shown, the measured aerosol density level 782 may not decrease to the baseline aerosol density level 754. At time 772-5, in response to the measured aerosol density level 782 failing to decrease to the baseline aerosol density level 754 or failing to decrease to the baseline aerosol density level 754 after a certain period of time, the fire sensing device may be identified as being obscured and / or the optical scattering chamber may be identified as being saturated. The variable airflow generator may be stopped at time 772-5, and the monitoring device (e.g., Figure 4 Monitoring device 401 in the embodiment of the present invention) and / or computing device (e.g., Figure 4 The computing device 430 in the embodiment may receive a message from the fire sensing device to notify a user that the fire sensing device is not functioning properly and / or requires maintenance due to being obscured or the optical scattering chamber being saturated.

[0074] Although specific implementations have been illustrated and described herein, those of ordinary skill in the art will appreciate that any arrangement calculated to achieve the same technique may be substituted for the specific implementations shown. This disclosure is intended to cover any and all modifications or variations of various implementations of the present disclosure.

[0075] It should be understood that the above description is given in an illustrative rather than limiting manner.By reading the above description, combinations of the above embodiments, as well as other embodiments not specifically described herein, will be apparent to those skilled in the art.

[0076] The scope of the various embodiments of the present disclosure includes any other applications using the above-described structures and methods.The scope of the various embodiments of the present disclosure should therefore be determined with reference to the appended claims, along with the full scope of equivalents to which such claims are entitled.

[0077] In the above detailed description, various features are grouped together in the exemplary embodiments shown in the drawings for the purpose of simplifying the disclosure. This method of disclosure should not be interpreted as reflecting an intention that the embodiments of the present disclosure require more features than are expressly recited in each claim.

[0078] Rather, as the following claims reflect, inventive subject matter lies in less than all features of a single disclosed embodiment.Thus the following claims are hereby incorporated into the Detailed Description, with each claim standing on its own as a separate embodiment.

Claims

1. A self-testing fire sensing device (100, 200, 300, 400), comprising: an adjustable particle generator (102, 302) configured to generate an aerosol; an optical scattering chamber (104, 204, 304) configured to measure an aerosol density level (582, 682, 782) of the aerosol; and A controller (122), the controller being configured to: The measured aerosol density level (582, 682, 782) is compared with the threshold aerosol density levels (556, 656, 756) for comparison; and The adjustable particle generator (102, 302) is caused to cease generating the aerosol in response to the measured aerosol density level (582, 682, 782) reaching and remaining at or above the threshold aerosol density level (556, 656, 756) for a specified period of time.

2. The device according to claim 1, further comprising a variable airflow generator (116, 216, 316) configured to generate an air flow to move the aerosol through the optical scattering chamber (104, 204, 304).

3. The device according to claim 2, wherein: The variable airflow generator (116, 216, 316) is configured to continue generating the airflow in response to the measured aerosol density level (582, 682, 782) reaching the threshold aerosol density level (556, 656, 756).

4. The device according to claim 3, wherein: The controller (122) is configured to cause the variable airflow generator (116, 216, 316) to stop generating the airflow after different specific time periods.

5. The device according to claim 3, wherein: The optical scattering chamber (104, 204, 304) is configured to measure additional aerosol density levels while continuing to generate the air flow.

6. The device according to claim 5, wherein: The controller (122) is configured to compare the additional measured aerosol density level with a baseline aerosol density level (554, 654, 754).

7. The device according to claim 6, wherein: The controller (122) is configured to cause the variable airflow generator (116, 216, 316) to stop generating the airflow in response to the additional measured aerosol density level reaching the baseline aerosol density level (554, 654, 754).

8. The device of claim 6, further comprising a memory (124), the memory being included in the controller (122), wherein: The memory (124) is configured to store the threshold aerosol density level (556, 656, 756) and the reference aerosol density level (554, 654, 754).

9. The device according to claim 1, wherein: The threshold aerosol density level (556, 656, 756) is 0.2 to 1.0 decibels per meter (dB / m).

10. The device according to claim 1, wherein: The threshold aerosol density level (556, 656, 756) is sufficient to trigger a fire response of the self-testing fire sensing device (100, 200, 300, 400) without saturating the optical scattering chamber (104, 204, 304).

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