CN217612611U

CN217612611U - Fire extinguishing device

Info

Publication number: CN217612611U
Application number: CN202220326404.XU
Authority: CN
Inventors: 彭建云; 罗武
Original assignee: Shenzhen Fuji Technology Co ltd
Current assignee: Shenzhen Fuji Technology Co ltd
Priority date: 2022-02-17
Filing date: 2022-02-17
Publication date: 2022-10-21
Anticipated expiration: 2032-02-17

Abstract

The utility model relates to the technical field of fire fighting equipment, and provides a fire extinguishing device, wherein a shell is provided with a containing cavity, and one side of the shell is provided with a plurality of nozzles communicated to the containing cavity; the explosive column is accommodated in the accommodating cavity and is used for burning to generate aerosol fire extinguishing agent which can be discharged to the outside of the shell through the nozzle; the coolant is contained in the containing cavity and is at least distributed between the explosive column and the nozzle; wherein the volume of the accommodating cavity is greater than or equal to the sum of the volume of the explosive column and the volume of the coolant. The utility model discloses a fire extinguishing device, when taking place the condition of a fire, the grain is lighted and produces the aerosol fire extinguishing agent of high temperature rapidly, and then, the aerosol fire extinguishing agent of high temperature flows through the coolant to being discharged the casing from the spout again after the coolant cooling and outside to catching fire the space, reaching the purpose of putting out a fire, and this fire extinguishing device can ensure effectively that the grain fully burns when being lighted, ensures fire extinguishing device's performance effectively, improves fire extinguishing device's fire control effect effectively.

Description

Fire extinguishing device

Technical Field

The utility model belongs to the technical field of fire-fighting equipment, especially, relate to a fire extinguishing apparatus.

Background

The aerosol fire extinguisher is a breakthrough product in the fire fighting field with ultrahigh fire extinguishing efficiency and reliability, and generally comprises a shell, a grain, a coolant and the like. When fire occurs, the explosive column is ignited and generates aerosol containing a large amount of micro solid particles through combustion of the explosive column to be dispersed in a firing space, so that flame combustion is inhibited, and the effect of extinguishing fire is achieved.

However, the existing aerosol fire extinguishing device is easy to cause the situation that the burning of the explosive column is insufficient, and further the fire extinguishing effect is poor.

SUMMERY OF THE UTILITY MODEL

An object of the utility model is to provide a fire extinguishing apparatus to solve current aerosol fire extinguishing apparatus and appear the insufficient problem of grain burning easily.

In order to achieve the above object, the utility model adopts the following technical scheme: a fire suppression apparatus, comprising:

the nozzle comprises a shell, a nozzle body and a nozzle body, wherein the shell is provided with an accommodating cavity, and one side of the shell is provided with a plurality of nozzles communicated to the accommodating cavity;

a cartridge received in the receiving cavity, the cartridge for combustion to produce an aerosol fire suppressant dischargeable via the spout to an exterior of the housing;

the coolant is accommodated in the accommodating cavity and is at least distributed between the explosive column and the nozzle;

wherein the volume of the accommodating cavity is greater than or equal to the sum of the volume of the explosive column and the volume of the coolant.

In one embodiment, the accommodating cavity is divided into a first cavity, a second cavity and a third cavity which are arranged in sequence, wherein the first cavity is used for accommodating the grain, the second cavity is communicated with the first cavity and the third cavity and is used for storing combustion-supporting gas, and the third cavity is used for accommodating the coolant.

In one embodiment, a communicating pipe is arranged in the second chamber, and the communicating pipe is used for storing the combustion-supporting gas.

In one embodiment, the communication pipe has a first communication port communicating with the first chamber and a second communication port communicating with the third chamber, and an aperture of the first communication port is larger than an aperture of the second communication port.

In one embodiment, the shell comprises an outer shell and an inner shell which is arranged on the inner side of the outer shell and has a heat insulation effect.

In one embodiment, a partition part is arranged on one side of the accommodating cavity in an inward protruding mode, and the explosive column and the coolant are respectively arranged on two opposite sides of the partition part.

In one embodiment, the coolant is distributed around the circumference of the charge.

In one embodiment, the housing is provided with a first outlet communicated to the accommodating cavity, and the fire extinguishing device further comprises an actuating structure for igniting the explosive column, wherein the actuating structure is arranged through the first outlet and is in contact with the explosive column.

In one embodiment, the actuation structure is a heat-sensitive wire;

and/or the starting structure is an electric starting structure, and the electric starting structure is started when the current flowing through the electric starting structure is larger than the preset current data.

In one embodiment, the housing is provided with a second outlet communicated to the accommodating cavity, and the fire extinguishing device further comprises a feedback structure which is arranged through the second outlet and used for feeding back a signal that the explosive column is burnt when the temperature in the accommodating cavity is higher than a preset temperature.

The utility model provides a beneficial effect lies in:

according to the fire extinguishing device provided by the embodiment of the utility model, when a fire occurs, the explosive column is ignited and rapidly generates the high-temperature aerosol fire extinguishing agent, and then the high-temperature aerosol fire extinguishing agent flows through the coolant, is cooled by the coolant and then is discharged out of the shell through the nozzle to the firing space, so that the fire extinguishing purpose is achieved; in addition, when the fire extinguishing device is small in size and the dosage of the corresponding grain is small, combustion-supporting gas such as air contained in a gap between the grain and the coolant can sufficiently meet the requirement of sufficient combustion of the grain, so that the grain can be fully combusted when being ignited; when the extinguishing device is large in size and large in dosage of corresponding explosive columns, combustion-supporting gas such as certain air is stored in the accommodating cavity in advance to guarantee that the explosive columns can be fully combusted when being ignited, so that the extinguishing device can effectively guarantee that the explosive columns can be fully combusted when being ignited, the service performance of the extinguishing device is effectively guaranteed, and the fire extinguishing effect of the extinguishing device is effectively improved.

Drawings

In order to more clearly illustrate the technical solutions in the embodiments of the present invention, the drawings needed to be used in the embodiments will be briefly described below, and it is obvious that the drawings in the following description are only some embodiments of the present invention, and it is obvious for those skilled in the art that other drawings can be obtained according to these drawings without creative efforts.

Fig. 1 is a first schematic view of a fire extinguishing apparatus according to a first embodiment of the present invention;

fig. 2 is a schematic view two of a fire extinguishing apparatus provided in the first embodiment of the present invention;

FIG. 3 is a first schematic view of a fire extinguishing apparatus according to a second embodiment of the present invention;

fig. 4 is a second schematic view of a fire extinguishing apparatus provided in the second embodiment of the present invention;

fig. 5 is a first schematic diagram of a fire extinguishing apparatus provided by a third embodiment of the present invention;

fig. 6 is a schematic view of a fire extinguishing apparatus according to a third embodiment of the present invention.

The reference numbers illustrate:

10-a housing; 11-a containment chamber; 111-a first cavity; 112-a second cavity; 113-a third chamber; 114-a partition; 12-a nozzle; 13-communicating tube; 131-a first communication port; 132-a second communication port; 14-a housing; 15-inner shell; 16-a first outlet; 17-a second outlet; 20-grain; 30-a coolant; 40-a start-up configuration; 50-feedback structure.

Detailed Description

In order to make the technical problem, technical solution and beneficial effects to be solved by the present invention more clearly understood, the following description is made in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative of the invention and are not intended to limit the invention.

In the description of the present invention, it is to be understood that the terms "length", "width", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", and the like indicate orientations or positional relationships based on the orientations or positional relationships shown in the drawings, and are merely for convenience of description and simplicity of description, and do not indicate or imply that the device or element referred to must have a particular orientation, be constructed and operated in a particular orientation, and thus, are not to be construed as limiting the present invention.

Furthermore, the terms "first", "second" and "first" are used for descriptive purposes only and are not to be construed as indicating or implying relative importance or implicitly indicating the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include one or more of that feature. In the description of the present invention, "a plurality" means two or more unless specifically limited otherwise.

In the present invention, unless otherwise explicitly specified or limited, the terms "mounted," "connected," "secured," and the like are to be construed broadly, e.g., as being fixedly connected, detachably connected, or integrated; can be mechanically or electrically connected; they may be directly connected or indirectly connected through intervening media, or may be connected through the use of two elements or the interaction of two elements. The specific meaning of the above terms in the present invention can be understood according to specific situations by those skilled in the art.

The following describes the specific implementation of the present invention in more detail with reference to specific embodiments:

example one

Referring to fig. 1, 2, 4 and 6, an embodiment of the present invention provides a fire extinguishing apparatus, which has a better fire extinguishing effect and is particularly suitable for relatively closed places such as communication equipment rooms, battery compartments, engine compartments and battery boxes.

The fire extinguishing apparatus includes a housing 10, a grain 20, and a coolant 30.

The shell 10 is provided with an accommodating cavity 11, and one side of the shell 10 is provided with a plurality of nozzles 12 communicated to the accommodating cavity 11; the grain 20 is accommodated in the accommodating cavity 11, the grain 20 is used for combustion to generate aerosol fire extinguishing agent which can be discharged to the outside of the shell 10 through the nozzle 12, and specifically, the grain 20 can be an S-type aerosol grain 20 or a K-type aerosol grain 20; the cooling agent 30 is accommodated in the accommodating cavity 11 and at least distributed between the grain 20 and the nozzle 12, so that the aerosol fire extinguishing agent discharged from the nozzle 12 can be cooled by flowing through the cooling agent 30, the temperature of the aerosol fire extinguishing agent discharged from the nozzle 12 can be effectively reduced, and the fire extinguishing effect of the fire extinguishing device can be effectively guaranteed.

Wherein, the volume of the accommodating cavity 11 is greater than or equal to the sum of the volume of the grain 20 and the volume of the coolant 30, specifically, when the fire extinguishing apparatus has a smaller volume and the corresponding dose of the grain 20 is smaller, for example, the dose of the grain 20 is 10 g or 20 g, the volume of the accommodating cavity 11 can be set to be equal to the sum of the volume of the grain 20 and the volume of the coolant 30, at this time, the combustion-supporting gas such as air contained in the gap between the grain 20 and the coolant 30 is enough to meet the requirement of sufficient combustion of the grain 20, thereby ensuring that the grain 20 can be sufficiently combusted when being ignited, and in addition, while ensuring that the grain 20 can be sufficiently combusted, the space of the accommodating cavity 11 of the fire extinguishing apparatus can be fully utilized, so that the fire extinguishing apparatus has a smaller volume, thereby effectively reducing the production cost of the fire extinguishing apparatus; when the fire extinguishing apparatus has a large volume and the corresponding explosive column 20 has a large dose, for example, when the dose of the explosive column 20 is 160 g, the volume of the accommodating cavity 11 can be set to be larger than the sum of the volume of the explosive column 20 and the volume of the coolant 30, and at this time, the extra space of the accommodating cavity 11 can store certain combustion-supporting gas such as air in advance, so as to ensure that the explosive column 20 is fully combusted when being ignited, thereby effectively reducing the risk that the explosive column 20 cannot be fully combusted or the explosive column 20 is abnormally extinguished due to insufficient combustion-supporting gas, effectively ensuring the service performance of the fire extinguishing apparatus, and effectively improving the fire extinguishing effect of the fire extinguishing apparatus.

In summary, in the fire extinguishing apparatus provided by the embodiment of the present invention, when a fire occurs, the grain 20 is ignited and rapidly generates a high-temperature aerosol fire extinguishing agent, and then the high-temperature aerosol fire extinguishing agent flows through the coolant 30, is cooled by the coolant 30, and is discharged from the nozzle 12 out of the casing 10 to the space on fire, so as to achieve the purpose of fire extinguishing; in addition, when the fire extinguishing device is small in size and the dosage of the corresponding grain 20 is small, the combustion-supporting gas such as air contained in the gap between the grain 20 and the coolant 30 can sufficiently meet the requirement of sufficient combustion of the grain 20, so that the grain 20 can be fully combusted when being ignited; when the extinguishing device is large in size and the dosage of the corresponding explosive column 20 is large, combustion-supporting gas such as certain air is stored in the accommodating cavity 11 in advance to ensure that the explosive column 20 can be fully combusted when being ignited, so that the extinguishing device can effectively ensure that the explosive column 20 can be fully combusted when being ignited, the service performance of the extinguishing device is effectively ensured, and the fire extinguishing effect of the extinguishing device is effectively improved.

Referring to fig. 2, in the present embodiment, the accommodating cavity 11 is divided into a first cavity 111, a second cavity 112 and a third cavity 113, which are sequentially arranged, wherein the first cavity 111 is used for accommodating the grain 20, the second cavity 112 communicates the first cavity 111 with the third cavity 113 and is used for storing combustion-supporting gas, and the third cavity 113 is used for accommodating the coolant 30.

By adopting the above scheme, when a fire occurs, the grain 20 placed in the first cavity 111 is ignited and burns, and certain combustion-supporting gas such as air is pre-stored in the second cavity 112 communicating the first cavity 111 and the third cavity 113, so that the combustion-supporting gas required by the combustion of the grain 20 can be timely and effectively supplemented towards the first cavity 111, so that the grain 20 can be fully burnt, the service performance of the fire extinguishing device can be effectively ensured, and the fire extinguishing effect of the fire extinguishing device can be effectively improved.

In addition, the first cavity 111 is used for accommodating the explosive column 20, and the third cavity 113 is used for accommodating the coolant 30, so that the explosive column 20 and the coolant 30 are accommodated in different cavities, and therefore, the installation and the placement of the explosive column 20 and the coolant 30 in different areas are more convenient, rapid and efficient for operators, the assembly efficiency of the fire extinguishing device can be effectively improved, the assembly and production costs of the fire extinguishing device can be effectively reduced,

referring to fig. 2, in the present embodiment, a communicating pipe 13 is disposed in the second chamber 112, and the communicating pipe 13 is used for storing combustion-supporting gas.

Through adopting above-mentioned scheme, through set up communicating pipe 13 in order to save combustion-supporting gas in second chamber 112, do benefit to the guarantee grain 20 and stabilize in first chamber 111, coolant 30 and stabilize in third chamber 113, and then guarantee effectively with the combustion-supporting gas's of grain 20 direct contact storage effective space, and then guarantee grain 20 can fully burn when being lighted to reach better fire suppression effect, guarantee extinguishing device's performance effectively.

Referring to fig. 2, in the present embodiment, the communication pipe 13 has a first communication port 131 communicating with the first chamber 111 and a second communication port 132 communicating with the third chamber 113, and an aperture of the first communication port 131 is larger than an aperture of the second communication port 132, that is, a cross-sectional area of the first communication port 131 is larger than a cross-sectional area of the second communication port 132.

By adopting the above scheme, the aperture of the first communication port 131 is larger than the aperture of the second communication port 132, on one hand, the aerosol fire extinguishing agent generated by the combustion of the grain 20 of the first cavity 111 is guided to flow from the first communication port 131 to the second communication port 132, so that the aerosol fire extinguishing agent is smoothly discharged out of the shell 10, and the purpose of timely extinguishing fire is achieved; on the other hand, the dust amount of dust generated by endothermic decomposition of the refrigerant in the third cavity 113 entering the second cavity 112 can be effectively reduced, so that the risk of accidental extinguishment due to reduction of contact area between the grain 20 and the combustion-supporting gas caused by the dust entering the first cavity 111 is effectively reduced, and the service performance of the fire extinguishing device is effectively guaranteed.

Referring to fig. 1, 3, 4 and 5, in the present embodiment, the housing 10 is provided with a first outlet 16 communicated to the accommodating cavity 11, the fire extinguishing apparatus further includes a starting structure 40 for igniting the grain 20, and the starting structure 40 is disposed through the first outlet 16 and contacts with the grain 20.

Through adopting above-mentioned scheme, wear to locate first outlet 16 and with the start structure 40 of the contact of powder column 20 through the setting, when taking place the condition of a fire, accessible start structure 40 is automatic, timely, light powder column 20 effectively to reach the purpose of in time putting out a fire, guarantee and improve extinguishing device's performance.

Referring to fig. 1, 3 and 5, in the present embodiment, the starting structure 40 is a heat-sensitive wire, which is started by self-ignition when the ambient temperature exceeds the ignition point;

and/or, actuation structure 40 is an electrical actuation structure 40, and electrical actuation structure 40 is actuated when the current flowing therethrough is greater than the predetermined current data.

By adopting the scheme, when a fire occurs, the powder column 20 can be ignited by the spontaneous combustion of the heat-sensitive wire when the heat-sensitive wire is heated, so that the aim of extinguishing the fire is fulfilled; and/or the electric starting structure 40 can heat the grain 20 to reach the ignition point of the grain 20 and then ignite the grain 20 by the current flowing through the electric starting structure 40 being larger than the preset current data, so as to achieve the purpose of extinguishing the fire; so, user of service can choose the start structure 40 of different modes for use as required in order to satisfy the needs of different use scenes, and user of service also can choose two kinds of start structures 40 simultaneously as required and start structure 40 when taking place the condition of a fire and ignite the powder column 20 more reliably in order to ensure, ensures effectively and improves extinguishing device's performance.

Referring to fig. 1, 3, 4 and 5, in the embodiment, the housing 10 is provided with a second outlet 17 communicated to the accommodating cavity 11, and the fire extinguishing apparatus further includes a feedback structure 50, where the feedback structure 50 is disposed through the second outlet 17 and is used for feeding back a signal that the charge 20 is burnt when the temperature in the accommodating cavity 11 is higher than a preset temperature, and feeding back a signal that the charge 20 is not burnt when the temperature in the accommodating cavity 11 is lower than or equal to the preset temperature.

By adopting the above scheme, by arranging the feedback structure 50 penetrating through the second outlet 17, when a fire occurs, the explosive column 20 is ignited and the temperature in the cavity of the accommodating cavity 11 is higher than the preset temperature, and at this time, the feedback structure 50 feeds back a signal that the explosive column 20 is burnt; on the contrary, when fire does not occur or when fire occurs and the explosive column 20 is not ignited, the temperature in the accommodating cavity 11 is less than or equal to the preset temperature, and the feedback mechanism feeds back a signal that the explosive column 20 is not combusted; so, convenient to use personnel look over in time, know extinguishing device's in service behavior, and convenient to use personnel in time changes extinguishing device, and in addition, when the external condition of a fire takes place and the powder column 20 state shows for not burning, user's accessible remote control starts structure 40 and starts to make powder column 20 ignite again in order to reach the purpose of in time putting out a fire.

Specifically, the feedback structure 50 may be a passive switch, and is normally open when the temperature inside the accommodating chamber 11 is less than or equal to a preset temperature, that is, when the fire extinguishing apparatus is in a standby state; the fire extinguishing device is normally closed when the temperature in the accommodating cavity 11 is higher than the preset temperature, namely when the fire extinguishing device is started; based on the characteristics of high anti-interference capability, high reliability, high stability and the like of the passive switch, the service performance of the feedback structure 50 is effectively guaranteed, and the service performance of the fire extinguishing device is effectively guaranteed.

Specifically, the feedback structure 50 may be connected with an indicator light, and the indicator light changes (for example, the color of the indicator light changes) when receiving different signals sent by the feedback structure 50, so that the user can visually, conveniently and quickly check and determine the signal fed back by the feedback structure 50, thereby effectively improving the service performance of the fire extinguishing apparatus.

Specifically, the feedback structure 50 can be associated with the starting structure 40, and when a fire occurs and the grain 20 is not normally ignited or the grain 20 is abnormally extinguished, the starting structure 40 can be controlled to start through the feedback structure 50, so that the starting structure 40 is restarted and the grain 20 is ignited, thereby ensuring that the grain 20 is smoothly combusted and the hot melt adhesive fire extinguishing agent is smoothly released, achieving the effect of extinguishing the fire, and effectively improving the service performance of the fire extinguishing apparatus.

Example two

The difference between the present embodiment and the first embodiment is:

referring to fig. 3 and 4, in the present embodiment, the housing 10 includes an outer shell 14 and an inner shell 15 disposed inside the outer shell 14 and having a heat insulation function. For example, the inner case 15 may be made of a plastic material.

By adopting the scheme, the inner shell 15 with the heat insulation effect is arranged in the outer shell 14, when fire occurs and the grain 20 is ignited, the inner shell 15 can effectively block heat generated by burning the grain 20 and achieve the physical heat insulation effect, the risk that the surface temperature of the outer shell 14 is too high due to excessive heat transmitted to the outer shell 14 and the fire extinguishing device design specification is exceeded is effectively reduced, and the using performance of the fire extinguishing device is guaranteed.

Referring to fig. 3, in the present embodiment, a dividing portion is inwardly protruded from a wall of one side of the accommodating chamber 11, and the grains 20 and the coolant 30 are respectively disposed at two opposite sides of the dividing portion.

Through adopting above-mentioned scheme, inwards be equipped with partition portion 114 through the one side chamber wall that holds chamber 11, when equipment extinguishing device, based on partition portion 114's separation, separate the shelves, the positioning action, do benefit to operating personnel based on partition portion 114 is convenient, swiftly, install with high-efficient subregion, place explosive column 20 and coolant 30, can improve extinguishing device's packaging efficiency effectively, reduce extinguishing device's equipment effectively, and a production cost is low, this embodiment is particularly useful for when extinguishing device is small, be not convenient for install the condition of explosive column 20 and fire extinguishing agent, for example, the dosage of explosive column 20 is 10 grams's extinguishing device.

EXAMPLE III

The difference between this embodiment and the first embodiment is:

referring to fig. 5 and 6, in the present embodiment, the coolant 30 is distributed on the periphery of the grains 20.

By adopting the scheme, the coolant 30 is arranged on the periphery of the grain 20, so that the contact area between the coolant 30 and the grain 20 can be effectively increased, the decomposition rate of the coolant 30 can be greatly improved when fire occurs and the grain 20 is ignited, the aerosol fire extinguishing agent flowing through the nozzle 12 can be effectively cooled, and the fire extinguishing effect is improved; in addition, the contact area between the coolant 30 and the shell 10 can be effectively increased, so that the heat transferred to the shell 10 by the combustion of the explosive column 20 can be effectively reduced, the risk that the surface temperature of the shell 14 is too high to exceed the design specification of the fire extinguishing device is effectively reduced, and the service performance of the fire extinguishing device is guaranteed. This embodiment is particularly suitable for use in fire extinguishing systems of relatively modest size, such as 20 grams of charge 20.

The present invention is not limited to the above preferred embodiments, and any modifications, equivalent replacements or improvements made within the spirit and principle of the present invention should be included within the protection scope of the present invention.

Claims

1. A fire suppression apparatus, comprising:

a charge received in the receiving cavity for combustion to produce an aerosol fire suppressant that is dischargeable to the exterior of the housing via the spout;

wherein the volume of the accommodating cavity is greater than or equal to the sum of the volume of the explosive column and the volume of the coolant;

the fire extinguishing device comprises a shell, a powder column and a starting structure, wherein the shell is provided with a first outlet communicated to the accommodating cavity, the starting structure is used for igniting the powder column, and the starting structure penetrates through the first outlet and is in contact with the powder column.

2. The fire extinguishing apparatus according to claim 1, wherein the receiving chamber is divided into a first chamber, a second chamber and a third chamber arranged in sequence, wherein the first chamber is used for receiving the grain, the second chamber communicates with the first chamber and the third chamber and is used for storing combustion-supporting gas, and the third chamber is used for receiving the coolant.

3. The fire extinguishing apparatus according to claim 2, wherein a communication pipe is provided in the second chamber, the communication pipe storing the combustion-supporting gas therein.

4. The fire extinguishing apparatus according to claim 3, wherein the communication pipe has a first communication port communicating with the first chamber and a second communication port communicating with the third chamber, and an aperture of the first communication port is larger than an aperture of the second communication port.

5. The fire extinguishing apparatus of claim 1, wherein the housing includes an outer shell and an inner shell disposed inside the outer shell and having a thermal insulation effect.

6. The fire extinguishing apparatus of claim 1, wherein a wall of one side of the receiving chamber is provided with a partition projecting inwardly, the grain and the coolant being provided on opposite sides of the partition.

7. The fire extinguishing apparatus of claim 1, wherein the coolant is distributed on the circumference of the grain.

8. Fire extinguishing apparatus according to any one of claims 1 to 7, wherein the activation structure is a heat-sensitive wire;

and/or the starting structure is an electric starting structure which is started when the current flowing through the electric starting structure is larger than the preset current data.

9. The fire extinguishing apparatus of any one of claims 1-7, wherein the housing is provided with a second outlet connected to the receiving chamber, the fire extinguishing apparatus further comprising a feedback structure passing through the second outlet and adapted to feedback a signal that the charge has been burned when the temperature in the receiving chamber is greater than a predetermined temperature.