CN218939071U

CN218939071U - Portable calibrating device for combustible gas alarm

Info

Publication number: CN218939071U
Application number: CN202223261103.2U
Authority: CN
Inventors: 张波
Original assignee: Sichuan Laifeng Fluid Equipment Manufacturing Co ltd
Current assignee: Sichuan Laifeng Fluid Equipment Manufacturing Co ltd
Priority date: 2022-12-06
Filing date: 2022-12-06
Publication date: 2023-04-28
Anticipated expiration: 2032-12-06

Abstract

The utility model discloses a portable calibrating device for a flammable gas alarm, which comprises a box body and a box cover, wherein a digital display area, an operation area, an interface area and an external connector which is communicated with a detection chamber in the box body and is used for connecting the alarm are arranged on the box body, a gas distribution chamber and a detection chamber are arranged in the box body, a first gas sensor is arranged in the detection chamber, an exhaust port and at least one gas inlet are arranged in the interface area, which are communicated with the gas distribution chamber, and a telescopic component which is used for protecting the external connector from collision is arranged between the external connector and the detection chamber. The calibrating device adopts the structure of the portable box body, has smaller volume, is convenient to use and operate and convenient to carry as a whole, and meanwhile, the box cover protects the connector and other interface components on the box body from external impact or collision damage. The device discharges exhaust gas through the exhaust port to avoid residue in the chamber.

Description

Portable calibrating device for combustible gas alarm

Technical Field

The utility model relates to the technical field of calibration devices, in particular to a portable calibration device for a combustible gas alarm.

Background

When the combustible gas in the industrial environment and the daily living environment (such as a kitchen using natural gas) leaks, the combustible gas alarm detects that the concentration of the combustible gas reaches the alarm value set by the alarm, the combustible gas alarm can send out an audible and visual alarm signal so as to remind people to take safety measures such as evacuation, forced air exhaust, equipment shutdown and the like. The gas alarm can be linked with related linkage equipment such as leakage in factory production, storage and transportation, and can drive systems such as exhaust, power supply cut-off, spraying and the like, so that explosion, fire and poisoning accidents are prevented, and the safe production is ensured. Are often used in chemical plants, petroleum, gas stations, steel plants, etc. where flammable gases are used or produced. And the fuel gas alarm is inspected and calibrated by a professional detecting instrument.

At present, a calibration device for a combustible gas alarm is generally characterized in that the combustible gas alarm is placed in a test box, then the combustible gas is introduced into the test box for detection, after detection, the combustible gas alarm needs to be taken out of the test box, and because the tightness of a pipeline in the test box is poor, the combustible gas is easy to leak in the process of taking out the combustible gas alarm, and the combustible gas is left in the test box.

In addition, some existing multichannel calibrating devices are used for communicating probes of an alarm with a box body at an external joint, and then introducing fuel gas for detection, gas leakage is easy to occur at the joint of the joint and the alarm due to poor sealing property, and the whole sealing property is difficult to ensure due to excessive internal connecting pipelines, so that the fuel gas is leaked inside the box body, and corrosion is caused to working components inside the box body, and the service life of the components is influenced.

Moreover, the connector on the box body of the existing multi-channel combustible gas alarm verification and calibration device is not provided with a protection device, and when the connector is damaged due to collision, the connection of pipelines can be affected.

Disclosure of Invention

The utility model aims to overcome the defects of the prior art and provides a portable calibrating device for a flammable gas alarm.

The aim of the utility model is realized by the following technical scheme:

the utility model provides a portable calibrating device of combustible gas alarm, includes the box, it has the case lid that is used for the guard box to articulate on the box, be equipped with the display area that is used for showing gas index data detection with the case lid articulated on the box, be used for the device to control the operation area of operation, be used for connecting the external device or the interface district of gas cylinder and the external joint that is used for the alarm to be connected of the inside detection room intercommunication of box, the inside of box is equipped with distribution chamber and detection room, the detection room is equipped with first gas sensor, and first gas sensor's probe is located the inside of detection room, the interface district is equipped with gas vent and at least one air inlet with the distribution chamber intercommunication, just be equipped with the expansion assembly that is used for protecting external joint from the impact injury between detection room.

Further, external joint inner wall is connected with flexible sealing washer and first valve, flexible sealing washer is located the external joint inner wall and is close to the position of port, and first valve is located between flexible sealing washer and the detection room, first valve is including the shell fragment that resets, resets the shell fragment and articulates in external joint inner wall through the hinge spring, and external joint inner wall same position is equipped with the dog that is used for spacing, is equipped with sealed the pad between shell fragment and the dog that resets.

Further, the telescopic assembly comprises a spring matched with the peripheral dimension of the external connector, a limiting table positioned at the joint of the box body and the external connector and a telescopic sealing sleeve connected with the detection chamber by the external connector, a boss for limiting the spring is arranged at the position, close to the port, of the external connector, and the spring is positioned between the boss and the limiting table and is sleeved on the periphery of the external connector.

Further, the air distribution chamber is connected with an air outlet and an air inlet on the surface of the box body through a sealing pipeline, a gas flowmeter is arranged on a pipeline connected with the air inlet, an air pump is arranged on a pipeline connected with the air outlet, and switching valves are arranged on the pipelines connected with the air outlet and the air inlet; the detection chamber is connected with the air distribution chamber through a sealing pipeline, the external connector is connected to the detection chamber, an air vent communicated with outside air is arranged on the detection chamber, and a second valve is arranged on the air vent.

Further, the second valve comprises a reset spring piece, the reset spring piece is hinged to the inner side of the hole wall through a hinge spring, a stop block used for limiting is arranged at the same position, and a sealing gasket is arranged between the reset spring piece and the stop block.

Further, the openings on the air distribution chamber connected with the external pipeline are distributed. The stress concentration and the processing difficulty can be reduced.

Further, the air inlet comprises a first air inlet and a second air inlet, and the air flow meters are arranged on pipelines connected with the air distribution chamber through the first air inlet and the second air inlet.

Further, the exhaust port is movably connected with an exhaust gas collecting device, and the exhaust gas collecting device is a sealed air bag or a sealed bag.

Further, the gas distribution chamber is provided with a second sensor, and a probe of the second sensor extends into the gas distribution chamber. The gas concentration detector is used for detecting the gas concentration in the mixing chamber and guaranteeing the accuracy of the prepared gas.

Further, the cross sections of the inner cavities of the air distribution chamber and the detection chamber are arc-shaped. The arc inner wall is favorable for the movement of gas molecules, so that the gas diffusion mixing rate in the cavity is faster.

The beneficial effects of the utility model are as follows:

1. the portable box body structure is adopted in the calibrating device, the air distribution chamber and the detection chamber for air distribution and detection are positioned in the box body, the external connector, the interface and the operation area are arranged on the surface of the box body, the size of the device is reduced, the use and the operation are more convenient, the whole device is convenient to carry, and meanwhile, the external connector and other interfaces are protected through the box cover and the telescopic assembly, so that the external connector and other interfaces are prevented from being impacted or knocked and damaged.

2. According to the utility model, the external joint is connected with the detection chamber through the sealing sleeve, the protection of the external joint is completed by matching with the telescopic assembly, the tightness of the connection between the external joint and the detection chamber is ensured, the gas leakage is prevented, meanwhile, the telescopic sealing ring in the external joint ensures the sealing in the process of being connected with the alarm probe to prevent the gas leakage, and the connection of alarms with different sizes can be adapted due to the retractility of the telescopic sealing ring.

3. The exhaust port and the accessory parts (air pump and valve) on the pipeline of the utility model discharge the exhaust gas after detection and calibration, thereby avoiding corrosion caused by the residual exhaust gas in the detection chamber and the mixing chamber and influencing the subsequent calibration.

Drawings

FIG. 1 is a schematic diagram of a flammable gas alarm calibration apparatus;

FIG. 2 is a schematic diagram of the device gas mixing and detection principle;

FIG. 3 is a schematic illustration of an external connector;

fig. 4 is a schematic view of a second valve on the vent.

In the figure, 1-case lid, 2-case, 3-handle, 4-interface area, 5-contact leg, 6-wire slot, 7-external connector, 8-indicator light, 9-charging port, 10-display area, 11-operating area, 12-first valve, 13-telescoping seal ring, 14-spring, 15-seal cartridge, 16-first sensor, 17-second sensor, 21-air distribution chamber, 2101-first air inlet, 2102-air outlet, 2103-second air inlet, 2104-air pump, 22-detection chamber, 2201-vent

Detailed Description

The technical solutions of the present utility model will be clearly and completely described below with reference to the embodiments, and it is apparent that the described embodiments are only some embodiments of the present utility model, but not all embodiments. All other embodiments, which can be made by a person skilled in the art without any inventive effort, are intended to be within the scope of the present utility model, based on the embodiments of the present utility model.

Referring to fig. 1, a portable calibration device for a flammable gas alarm comprises a case body 2 and a case cover 1, wherein the case cover 1 is hinged on the case body 2, and a contact pin 5 is arranged on the bottom surface of the case body 2 so that the case body 2 can be stably placed when in use. A handle 3 is arranged on the side surface of the box body 2 for carrying. The front of the box body 2 (i.e. one surface of the hinge of the box cover 1) is provided with a plurality of partitions, including a display area 10 for displaying data information, an operation area 11 for setting a power switch and other operation switches, an interface area 4 for connecting an external pipeline, a device or a gas cylinder and an external connector 7 for connecting an alarm to be calibrated, in addition, the surface of the box body 2 is also provided with an indicator lamp 8 with a signal display and a wire slot 6 for storing a charging cable at a charging port 9. Grooves which are matched with the connectors and the switch buttons on the box body 2 are arranged on the inner side of the box cover 1 and used for protecting the connectors, the interfaces and the like, and foam gaskets are also connected on the inner side surface of the box cover 1 and used for insulating, preventing dust and buffering external vibration.

Referring to fig. 2, and referring to fig. 1, a gas detection mixing chamber 21 and a detection chamber 22 are provided in the interior of the case 2, and a standard gas and an auxiliary gas are mixed in the gas distribution chamber 22 to achieve the preparation of a gas with a specified concentration, and in this embodiment, the inner wall profiles of the gas detection mixing chamber 21 and the detection chamber 22 are arc-shaped, which is beneficial to the diffusion movement of gas molecules in the room, the standard gas is a high-purity target gas (hereinafter referred to as "target gas") detected by an alarm, and the auxiliary gas is a gas for diluting the mixed target gas, which does not react with the target gas, typically nitrogen. As shown in the figure, the gas distribution chamber 21 is connected with the detection chamber 22 through a sealed pipeline to realize the intercommunication of indoor gas, and the detection chamber 22 is communicated with the external connector 7, the detection chamber 22 is also provided with a first concentration detection sensor 16 for monitoring the indoor gas concentration, and the detection probe of the sensor extends into the detection chamber 22.

Referring to fig. 3, for the specific structure of the external connection joint 7, the inner wall of the external connection joint is connected with a telescopic sealing ring 13 and a first valve 12, the telescopic sealing ring 13 is located at a position, close to the port, of the inner wall of the external connection joint 7, and the first valve 12 is located between the telescopic sealing ring 13 and the detection chamber 22. The external connector 7 and the detection chamber 22 are provided with a telescopic component for protecting the external connector 7 from impact injury, the telescopic component comprises a spring 14 which is matched with the peripheral size of the external connector 7, a limit table which is positioned at the joint of the box body 2 and the external connector 7, and a sealing sleeve 15 which is connected with the external connector 7 and the detection chamber 22, a boss for limiting the spring is arranged at the position of the external connector 7, which is close to the port, and the spring 14 is positioned between the boss and the limit table and is sleeved on the peripheral surface of the external connector 7.

The sealing sleeve 15 connects the external connector 7 with the air distribution chamber 21, ensures the tightness of the connection of the external connector 7 and the air distribution chamber, and realizes the expansion of the external connector 7 by matching with the expansion assembly, specifically, when the box cover 1 and the box body 2 are closed, the external connector 7 is compressed into the box body 2 by being pressed, at the moment, the external connector 7 is fastened between the box cover 1 and the box body 2 through the spring 14 and the box cover 1, and in view of the vibration reduction of the spring 7, the box body 2 receives external impact, and the external connector 7 cannot be damaged.

The telescopic sealing ring 13 inside the external connector 7 is in a gathering state due to the elasticity of the telescopic sealing ring, and when the probe of the combustible gas alarm stretches into the external connector 7, the telescopic sealing ring 13 is compressed and clings to the surface of the probe, so that the gas in the detection chamber 22 is prevented from leaking through the probe. The telescopic sealing ring 13 also has the function of being capable of adapting to the insertion of probes of alarms with different models and sizes, and tightly wrapping the inserted probes by virtue of the sealing telescopic performance of the telescopic sealing ring, so that no gas leakage is ensured in the calibration process.

The first valve 12 comprises a reset spring, the reset spring is hinged to the inner wall of the external joint 7 through a hinge spring, a stop block for limiting is arranged at the same position of the inner wall of the external joint 7, and a sealing gasket is arranged between the reset spring and the stop block. Under normal state, the reset spring is tightly attached to the sealing gasket by virtue of elasticity, the sealing performance of the cavity is maintained, and when the probe of the combustible gas alarm stretches into the inner wall of the external connector 7, the reset spring is jacked up, and the probe of the alarm is communicated with the inside of the detection chamber 22. When the calibration is completed and the alarm is pulled out, the probe is separated from the external connector 7, and the reset elastic sheet resets under the elastic action and is attached with the tight sealing gasket. In other embodiments, the first valve may be a hydraulically, electrically or pneumatically controlled valve, for example, but such a valve is simpler in construction and less costly in comparison to the present embodiment.

In this embodiment, in addition to the first sensor 16 provided in the detection chamber 22, a second sensor 17 is provided in the gas distribution chamber 21, and the purpose of this embodiment is to monitor the gas content of each component in real time during the gas distribution in the gas distribution chamber 21, and to accurately distribute the gas of the desired concentration. The beneficial effects that this setting brought are: compared with the method that only the detection chamber 22 is provided with the gas sensor for monitoring the gas concentration around the external connector 7, the embodiment is beneficial to monitoring the content of nitrogen and standard gas in the distribution chamber 21 in the gas preparation process by arranging the sensors in the distribution chamber 21 and the detection chamber 22 respectively, so that the input quantity of the nitrogen or the standard gas can be adjusted in time, and the risk and waste caused by excessive quantity are avoided.

(in the process of the gas molecules from the gas distribution chamber 21 to the detection chamber 22, since the gas molecules are diffused from the high concentration to the low concentration region, before the gas molecules are uniformly mixed, the concentration of the label in the gas distribution chamber 21 is higher than that in the detection chamber 22, and a certain time is required for the concentration balance of the two chambers to be achieved, in this process, if only the detection chamber 22 is monitored for the concentration, the concentration of the gas in the gas distribution chamber 21 is likely to be too high when the concentration detection standard is reached.)

The air distribution chamber 21 is provided with an air outlet 2102 and at least one air inlet, and the tail ends of the air outlet 2102 and the air inlet are respectively provided with a switch valve, and the switch valves can be hydraulic valves or pneumatic valves. The connection pipe of the exhaust port 2102 is further provided with an air pump 2104 for exhausting air, when the alarm calibration and detection are finished, the pressure is released through the exhaust port 2102, the indoor exhaust gas is pumped out by the air pump 2104, meanwhile, the exhaust port is connected with an exhaust gas collecting device for collecting the exhausted exhaust gas for harmless treatment, and the exhaust gas collecting device can use a sealed air bag or a sealed bag.

The inlet is used for the passage of the standard gas and nitrogen gas, while the exhaust 2102 is used for the exhaust of the exhaust gas after calibration. In some embodiments, only one air inlet can be provided, and in the process of gas configuration and mixing, the same air inlet is used for introducing standard gas and nitrogen, so that on one hand, the number of holes on the gas distribution chamber 21 can be reduced, corresponding pipeline connection and parts are reduced, the cost is reduced, and on the other hand, the fewer holes are beneficial to guaranteeing the sealing performance of the chamber. However, a single air inlet cannot be filled with standard gas and nitrogen at the same time, and only the nitrogen and the standard gas can be sequentially filled after one another, so that the defects are that the content of each gas component in the gas distribution chamber is difficult to dynamically adjust, the concentration of the indoor gas cannot be accurately controlled, and the accuracy calibration and detection of the combustible gas alarm are not facilitated.

In this embodiment, the gas distribution chamber 21 is provided with two gas inlets, namely a first gas inlet 2101 and a second gas inlet 2103, which are respectively used for inputting nitrogen and standard gas, so that the gas inlet amount of each gas inlet can be controlled respectively, and the gas concentration (or relative content) in the gas distribution chamber 21 can be adjusted in real time. And the first intake port 2101, the exhaust port 2102 and the second intake port 2103 are arranged in a dispersed manner on the distribution chamber 21 for the purpose of: firstly, as the chambers of the air distribution chamber 21 and the detection chamber 22 are smaller, the difficulty of intensively forming a plurality of holes on the chamber wall is high, and the connection of a sealing pipeline is not facilitated; secondly, because the atmospheric pressure that the cavity bore is great, a plurality of trompils concentrate and same district can lead to stress concentration, makes this regional material intensity and life-span greatly reduced, and then influences use and safety. Thus, the dispersed arrangement of the first intake port 2101, the exhaust port 2102, and the second intake port 2103 on the gas distribution chamber 21 helps to solve the above-described drawbacks.

In coordination with the use of the air pump 2104 during the venting process, a vent 2201 is provided on the detection chamber 22, a second valve is provided on the vent 2201, and the vent 2201 is in communication with air. When the air pump 2104 operates to draw off the exhaust air, the vent 2201 opens to allow outside air to enter, preventing negative pressure from forming in the room.

The second valve is similar to the first valve 12, specifically, referring to fig. 4, the second valve includes a reset spring, which is hinged to the inner side of the wall of the vent 2201 through a hinge spring, a stop for limiting is disposed at the same position, and a sealing gasket is disposed between the reset spring and the stop. In a normal state, the reset elastic sheet is tightly attached to the sealing gasket. When the air pump 2104 exhausts to the outside and the air pressure in the detecting chamber 22 is obviously lower than the external air pressure, the air pressure acting on the reset spring is stronger than the elastic force, at this time, the reset spring is jacked up, and the external air enters the detecting chamber 22 through the vent 2201 and flows to the exhaust port 2102.

The application method of the device and the specific working process are as follows:

s1: the cover 1 is opened, the nitrogen gas cylinder and the standard gas cylinder are connected through the first air inlet 2101 and the second air inlet 2103, and the waste gas collecting device is connected through the air outlet 2102.

S2: and (5) starting. The on-off valves on the first air inlet 2101 and the air outlet 2102 and the valves on the nitrogen cylinder are opened, nitrogen is continuously introduced into the air distribution chamber 21 and the detection chamber 22, air in the air distribution chamber 21 and the detection chamber 22 is exhausted, and the nitrogen introducing time and the nitrogen introducing amount are controlled according to the first sensor 16 and the second sensor 17 in the process.

S3: after the air is exhausted, the probe of the combustible gas alarm is inserted into the external connector 7, meanwhile, the switch valves on the first air inlet 2101 and the air outlet 2102 and the nitrogen gas of the nitrogen gas cylinder are closed, the standard gas is slowly introduced through the second air inlet 2103, the standard gas introduction amount is controlled according to the first sensor 16 and the second sensor 17, and the increase of the concentration of the standard gas in the gas distribution chamber 21 and the detection chamber 22 (generally about 25% of the lower explosion limit) is strictly controlled. After the concentration reaches the requirement, the switch valve on the second air inlet 2103 is closed, the standard air is stopped to be introduced, the calibration is started, the data change of the display area and the state of the alarm are observed, and the record is carried out.

S4: after the alarm calibration test is completed, the switch valve on the exhaust port 2102 is opened, then the air pump 2104 is started, the air in the air distribution chamber 21 and the air in the detection chamber 22 are discharged into the waste gas collecting device, in the process, the second valve in the vent 2201 positioned on the detection chamber 22 is not opened yet because the air pressure in the early-stage chamber is higher than the outside, after the indoor air pressure is reduced to a certain degree, the second valve is opened and the outside air is introduced, under the action of the air pump 2104, the waste gas in the detection chamber 22 and the air distribution chamber 21 is completely discharged into the waste gas collecting device, and the waste gas is prevented from remaining in the room and leaking into the box body 2. And according to the detection data of the first sensor 16 and the second sensor 17, after the indoor waste gas is completely removed, the alarm is pulled out, and the switch valve on the exhaust port 2102 is closed.

S5: and (5) shutting down. The exhaust gas collecting device and the gas cylinder are removed and the cover 1 is closed.

The portable box body 2 is adopted in the calibrating device, the air distribution chamber 21 and the detection chamber 22 for air distribution and detection are positioned in the box body 2, the external connector 7, the interface and the operation area are arranged on the surface of the box body 2, the size of the device is reduced, the use and the operation are more convenient, the whole device is convenient to carry, and meanwhile, the external connector 7 and other interfaces are protected through the box cover 1 and the telescopic assembly, so that the external connector 7 is prevented from being impacted or knocked and damaged. In addition, in the utility model, the external joint 7 is connected with the detection chamber 22 through the sealing sleeve 15, besides the protection of the external joint 7 is completed by matching with the telescopic component, the tightness of the connection of the external joint 7 with the detection chamber 22 is ensured, the gas leakage is prevented, meanwhile, the telescopic sealing ring 13 in the external joint 7 ensures the sealing in the process of being connected with the alarm probe to prevent the gas leakage, and the connection of alarms with different sizes can be adapted due to the retractility of the telescopic sealing ring. Meanwhile, the exhaust port 2102 and accessory parts (air pump and valve) on the pipeline of the exhaust port provided by the utility model discharge exhaust gas after detection and calibration, so that the exhaust gas is prevented from being left in the detection chamber 22 and the mixing chamber 21 to cause corrosion and influence the subsequent calibration.

The foregoing is merely a preferred embodiment of the utility model, and it is to be understood that the utility model is not limited to the form disclosed herein but is not to be construed as excluding other embodiments, but is capable of numerous other combinations, modifications and environments and is capable of modifications within the scope of the inventive concept, either as taught or as a matter of routine skill or knowledge in the relevant art. And that modifications and variations which do not depart from the spirit and scope of the utility model are intended to be within the scope of the appended claims.

Claims

1. The utility model provides a portable calibrating device of combustible gas alarm, includes box (2), its characterized in that: the box body (2) is hinged with a box cover (1) for protecting the box body (2), a display area (10) for detecting the explicit gas index data is arranged on one surface of the box body (2) hinged with the box cover (1), an operation area (11) for controlling and operating the device, an interface area (4) for connecting an external device or a gas bottle and an external connector (7) which is communicated with an alarm and is used for being connected with an internal detection chamber (22) of the box body (2), a gas distribution chamber (21) and the detection chamber (22) are arranged in the box body (2), a first gas sensor (16) is arranged in the detection chamber (22), a probe of the first gas sensor (16) is positioned in the detection chamber (22), an exhaust port (21) and at least one gas inlet which are communicated with the gas distribution chamber (21) are arranged in the interface area (4), and a telescopic component for protecting the external connector (7) from being damaged by impact is arranged between the external connector (7) and the detection chamber (2102).

2. A combustible gas alarm portable calibration device as defined in claim 1 wherein: the utility model discloses a high-pressure gas-liquid-tight valve, including external joint (7) inner wall, external joint (7) inner wall is connected with flexible sealing washer (13) and first valve (12), flexible sealing washer (13) are located the position that external joint (7) inner wall is close to the port, and first valve (12) are located between flexible sealing washer (13) and detection room (22), first valve (12) are including the shell fragment that resets, and the shell fragment that resets articulates in external joint (7) inner wall through the hinge spring, and external joint (7) inner wall same position is equipped with the dog that is used for spacing, is equipped with sealed the pad between shell fragment that resets and the dog.

3. A combustible gas alarm portable calibration device as defined in claim 1 wherein: the telescopic assembly comprises a spring (14) which is matched with the outer peripheral dimension of the external connector (7), a limiting table which is positioned at the joint of the box body (2) and the external connector (7) and a telescopic sealing sleeve (15) which is connected with the detection chamber (22), a boss which is used for limiting the spring (14) is arranged at the position, close to the port, of the external connector (7), and the spring (14) is positioned between the boss and the limiting table and is sleeved on the outer periphery of the external connector (7).

4. A combustible gas alarm portable calibration device as defined in claim 1 wherein: the air distribution chamber (21) is connected with an air outlet (2102) and an air inlet on the surface of the box body (2) through a sealing pipeline, an air flowmeter is arranged on a pipeline connected with the air inlet, an air pump (2104) is arranged on a pipeline connected with the air outlet (2102), and switching valves are arranged on pipelines connected with the air outlet (2102) and the air inlet; the detection chamber (22) is connected with the air distribution chamber (21) through a sealing pipeline, the external connector (7) is connected to the detection chamber (22), an air vent (2201) communicated with external air is arranged on the detection chamber (22), and a second valve is arranged on the air vent (2201).

5. The portable calibration device for a flammable gas alarm of claim 4, wherein: the second valve comprises a reset elastic piece which is hinged to the inner side of the hole wall through a hinge spring, a stop block used for limiting is arranged at the same position, and a sealing gasket is arranged between the reset elastic piece and the stop block.

6. The portable calibration device for a flammable gas alarm of claim 4, wherein: the openings of the air distribution chamber (21) connected with the external pipeline are distributed.

7. The portable calibration device for a flammable gas alarm of claim 4, wherein: the air inlet comprises a first air inlet (2101) and two air inlets (2103), and pipelines connected with the first air inlet (2101) and the second air inlet (2103) and the air distribution chamber (21) are respectively provided with the air flow meter.

8. The portable calibration device for a flammable gas alarm of claim 4, wherein: the exhaust port (2102) is movably connected with an exhaust gas collecting device, and the exhaust gas collecting device is a sealed air bag or a sealed bag.

9. A combustible gas alarm portable calibration device as defined in claim 1 wherein: the air distribution chamber (21) is provided with a second sensor (17), and a probe of the second sensor (17) extends into the air distribution chamber (21).

10. A combustible gas alarm portable calibration device as defined in claim 1 wherein: the cross sections of the inner cavities of the air distribution chamber (21) and the detection chamber (22) are arc-shaped.