A gas alarm with online calibration function

Abstract

The utility model discloses a gas alarm with on -line calibration function, including alarm body, alarm device, gas supply system, and be used for detecting gas content's sensor probe, and gas supply system is fixedly connected with alarm body, is used for providing the sensor probe with the gas to be measured, gas supply system includes the pure air providing mechanism for zero point calibration, the standard content gas providing mechanism for range calibration and control valve, and control valve is used for switching the gas provided to sensor probe, and the gas alarm with on -line calibration function still includes control system, and control system is electrically connected with control valve, sensor probe and alarm device, is used for controlling control valve action and control alarm device and sends out alarm. The gas alarm with on -line calibration function has the function of on -line calibration.

Description

Technical Field

[0001] This utility model relates to the field of gas alarms, specifically to a gas alarm with online calibration function. Background Technology

[0002] A gas alarm is a safety device used to detect the concentration of a specific gas in the environment and issue an alarm when the concentration reaches a dangerous level. It is widely used in industrial, residential, and commercial settings.

[0003] Gas alarms can ensure the normal production activities of factories and the safety of workers. However, after industrial gas alarms are installed, it is necessary to send people to test the alarms regularly to determine whether the alarms are functioning properly. Different alarms detect different target gases, and it is difficult to complete the testing work on site. The alarms need to be disassembled and returned to the laboratory for calibration, which is time-consuming and labor-intensive. Utility Model Content

[0004] The purpose of this invention is to provide a gas alarm with an online calibration function, which has an online calibration capability.

[0005] To achieve the above objectives, this utility model provides a gas alarm with online calibration function, including an alarm body, an alarm device, a gas supply system, and a sensor probe for detecting gas content. The gas supply system is fixedly connected to the alarm body and is used to provide the gas to be tested to the sensor probe.

[0006] The gas supply system includes a pure air supply mechanism for zero-point calibration, a standard content gas supply mechanism for range calibration, and a control valve for switching the gas supplied to the sensor probe.

[0007] Gas alarms with online calibration function also include a control system, which is electrically connected to the control valve, sensor probe and alarm device, and is used to control the operation of the control valve and the alarm device to issue an alarm.

[0008] Preferably, the clean air supply mechanism includes an air pump, a filter, and an air supply pipe, with the outlet of the air supply pipe facing the sensor probe.

[0009] Preferably, the inlet of the filter is open to the environment, and a certain amount of standard content gas is stored in the standard content gas supply unit.

[0010] Preferably, the control valve is configured as a two-position three-way valve, with the two valve core positions corresponding to the connection of pure air to the air pump and the connection of standard content gas to the air pump, respectively.

[0011] Preferably, the filter is connected to the normally open port of the control valve, and the standard content gas supply mechanism is connected to the normally closed port of the control valve.

[0012] Preferably, the standard content gas supply mechanism is configured as a gas bag, which is detachably connected to the control valve.

[0013] Preferably, the capacity of the air bag is set to 10-1000ml, and the inflation pressure of the air bag is set to 0.1-0.3Mpa.

[0014] Preferably, a flow limiting valve is also provided between the control valve and the air pump.

[0015] Preferably, the filter is filled with an adsorbent material, which can be one or more of activated carbon, molecular sieves, and silica gel.

[0016] According to the above technical solution, the gas supply system of this utility model can provide zero-point calibration gas and range calibration gas to a gas alarm with online calibration function. The control system controls the control valve to first release zero-point calibration gas to the sensor probe through the gas supply system. The sensor probe detects the zero-point calibration gas and displays the detection value. The control system compares the value detected by the sensor probe with a preset first value. If the detected value is not equal to the first value, the control system rewrites the control circuit of the sensor probe to rewrite the value as the first value. The first value is the starting point of the measurement range of the sensor probe.

[0017] The control system then controls the control valve to release range calibration gas to the sensor probe through the gas supply system. The sensor probe detects this range calibration gas and displays the detected value. The control system compares the value detected by the sensor probe with a second value predicted by the system. If the detected value is not equal to the second value, the control system rewrites the control circuit of the sensor probe to rewrite the value as the second value. The second value is the measured value corresponding to the range calibration gas.

[0018] In one embodiment, the gas used for zero-point calibration is pure air, and the first value corresponding to this pure air is 0. When the sensor probe detects this pure air, it needs to display that the content of the gas to be measured is 0. If the value displayed by the sensor probe is not 0, the control system needs to rewrite 0 into the control circuit of the sensor probe, thereby completing the zero-point calibration of the gas alarm with online calibration function.

[0019] In one embodiment, the range calibration gas is set to be within the detection range of the gas to be measured by the gas alarm with online calibration function. After the zero-point calibration is completed, the control valve controls the gas supply system to release the range calibration gas to the sensor probe. The sensor probe detects the content of the gas to be measured in the range calibration gas and displays the measurement value corresponding to the range calibration gas.

[0020] The content of the gas to be tested in the calibration gas is set to a fixed value, and therefore, the corresponding measurement value is fixed. This fixed measurement value is set as the second value and written into the alarm. During the calibration of the gas alarm with online calibration function, the sensor probe detects the content of the gas to be tested in the calibration gas. The control system compares the measured value with the second value. If the two are equal, it means that the measurement value of the gas alarm with online calibration function is still reliable. If the two are not equal, the control system directly writes the second value into the circuit of the sensor probe to realize the range calibration of the gas alarm with online calibration function.

[0021] When the control system controls the control valve to operate, but the control valve does not respond, or when other abnormal situations occur during the calibration process, the alarm device will sound an alarm. Preferably, the alarm device is set as an audible and visual alarm. The audible and visual alarm device can remind the staff to pay attention to the gas alarm with online calibration function and handle the abnormal situation in the gas alarm with online calibration function.

[0022] Other features and advantages of this invention will be described in detail in the following detailed description section. Attached Figure Description

[0023] The accompanying drawings are provided to further illustrate the present invention and form part of the specification. They are used together with the following detailed description to explain the present invention, but do not constitute a limitation thereof. In the drawings:

[0024] Figure 1 This is a structural diagram of a gas alarm with online calibration function;

[0025] Figure 2 This is a structural diagram of a gas alarm with online calibration function;

[0026] Figure 3 This is a schematic diagram of the structure of a filter;

[0027] Figure 4 This is a schematic diagram of the structure of a filter;

[0028] Figure 5 This is a schematic diagram of the structure of a filter;

[0029] Figure 6 This is a flowchart of an online calibration method for a gas alarm with online calibration function.

[0030] Explanation of reference numerals in the attached figures

[0031] 1. Alarm unit 2. Alarm device

[0032] 3 sensor probes 41 control valves

[0033] 42 Air pump 43 Filter

[0034] 44 Gas supply pipe 431 Inlet end

[0035] 45 air bag 46 flow limiting valve

[0036] 201 Activated Carbon, 202 Molecular Sieves

[0037] 203 silicone Detailed Implementation

[0038] The specific embodiments of this utility model will be described in detail below with reference to the accompanying drawings. It should be understood that the specific embodiments described herein are for illustration and explanation only and are not intended to limit the scope of this utility model.

[0039] In this utility model, unless otherwise stated, directional words such as "orientation" and "between" included in the terminology only represent the orientation of the term in its normal use or are common terms understood by those skilled in the art, and should not be regarded as limitations on the term.

[0040] A gas alarm with online calibration function includes an alarm body 1, an alarm device 2, a gas supply system, and a sensor probe 3 for detecting gas content. The gas supply system is fixedly connected to the alarm body 1 and is used to supply the gas to be tested to the sensor probe 3.

[0041] The gas supply system includes a pure air supply mechanism for zero-point calibration, a standard content gas supply mechanism for range calibration, and a control valve 41, which is used to switch the gas supplied to the sensor probe 3.

[0042] The gas alarm with online calibration function also includes a control system, which is electrically connected to the control valve 41, the sensor probe 3 and the alarm device 2, and is used to control the operation of the control valve 41 and control the alarm device 2 to issue an alarm.

[0043] Through the implementation of the above technical solution, the gas supply system can provide zero-point calibration gas and range calibration gas to the gas alarm with online calibration function. The control system controls the control valve 41 to first release the zero-point calibration gas to the sensor probe 3 through the gas supply system. The sensor probe 3 detects the zero-point calibration gas and displays the detection value. The control system compares the value detected by the sensor probe 3 with a preset first value. If the detected value is not equal to the first value, the control system rewrites the control circuit of the sensor probe 3 to rewrite the value as the first value. The first value is the starting point of the measurement range of the sensor probe 3.

[0044] The control system then controls control valve 41 to release range calibration gas to sensor probe 3 through the gas supply system. Sensor probe 3 detects this range calibration gas and displays the detected value. The control system compares the value detected by sensor probe 3 with a second value predicted by the system. If the detected value is not equal to the second value, the control system rewrites the control circuit of sensor probe 3 to rewrite the value as the second value. The second value is the measurement value corresponding to the range calibration gas.

[0045] In one embodiment, the gas used for zero-point calibration is pure air, and the first value corresponding to this pure air is 0. When the sensor probe 3 detects this pure air, it needs to display that the content of the gas to be measured is 0. If the value displayed by the sensor probe 3 is not 0, the control system needs to rewrite 0 into the control circuit of the sensor probe 3, thereby completing the zero-point calibration of the gas alarm with online calibration function.

[0046] In one embodiment, the range calibration gas is set to be within the detection range of the gas to be measured by the gas alarm with online calibration function. After the zero-point calibration is completed, the control valve 41 controls the gas supply system to release the range calibration gas to the sensor probe 3. The sensor probe 3 detects the content of the gas to be measured in the range calibration gas and displays the measurement value corresponding to the range calibration gas.

[0047] The content of the gas to be tested in the calibration gas is set to a fixed value, and therefore, the corresponding measurement value is fixed. This fixed measurement value is set as the second value and written into the alarm. During the calibration of the gas alarm with online calibration function, the sensor probe 3 detects the content of the gas to be tested in the calibration gas. The control system compares the measured value with the second value. If the two are equal, it means that the measurement value of the gas alarm with online calibration function is still reliable. If the two are not equal, the control system directly writes the second value into the circuit of the sensor probe 3 to realize the range calibration of the gas alarm with online calibration function.

[0048] When the control system controls the control valve 41 to operate, but the control valve 41 does not respond, or when other abnormal situations occur during the calibration process, the alarm device 2 will sound an alarm. Preferably, the alarm device 2 is set as an audible and visual alarm. The audible and visual alarm device 2 can remind the staff to pay attention to the gas alarm with online calibration function and handle the abnormal situation in the gas alarm with online calibration function.

[0049] In this embodiment, preferably, the clean air supply mechanism includes an air pump 42, a filter 43, and an air supply pipe 44, with the outlet of the air supply pipe 44 facing the sensor probe 3.

[0050] Air is drawn from the environment by the air pump 42, and the air is filtered by the filter 43 to become pure air that meets the calibration requirements. This pure air is sent into the alarm body 1 near the sensor probe 3 through the air supply pipe 44. After the sensor probe 3 is surrounded by pure air, it begins to detect the pure air. The detection result is compared with the set 0 value. If the detection result of the sensor probe 3 is not 0, the control system modifies the detection result to 0 through the control circuit of the sensor probe 3, thereby realizing the zero-point calibration of the sensor probe 3.

[0051] By setting up the air pump 42, reliable air extraction from the environment can be achieved.

[0052] In this embodiment, preferably, the inlet end 431 of the filter 43 is open to the environment, and a certain amount of standard content gas is stored in the standard content gas supply mechanism.

[0053] The inlet end 431 of the filter 43 is open to the environment. Under the action of the air pump 42, air can overcome the resistance in the filter 43 and enter the filter 43 through the inlet end 431, and finally be discharged to the sensor probe 3 through the air supply pipe 44.

[0054] The standard content gas supply mechanism stores a certain amount of standard content gas. When the standard content gas needs to be used, the pump 42 can be started to extract it from the standard content gas supply mechanism.

[0055] Preferably, the filter 43 is connected in parallel with the standard content gas supply mechanism and then connected to the air pump 42 through the control valve 41. The control system selects the gas introduced into the air pump 42 through the control valve 41, thereby realizing the calibration of the gas alarm with online calibration function.

[0056] This approach allows for the use of only one air pump 42 to meet the calibration requirements of a gas alarm with online calibration function, thus simplifying the structure of the gas alarm with online calibration function.

[0057] In this embodiment, preferably, the control valve 41 is configured as a two-position three-way valve, with the two positions of the valve core of the control valve 41 corresponding to the connection of pure air to the air pump 42 and the connection of standard content gas to the air pump 42, respectively.

[0058] The inlet of control valve 41 is connected to filter 43 and standard content gas supply mechanism, respectively, and the outlet of control valve 41 is connected to air pump 42. This control valve 41 is configured as a two-position three-way valve. The two valve core positions of control valve 41 correspond to the connection of pure air to air pump 42 and the connection of standard content gas to air pump 42, respectively. Therefore, by switching the valve core position of control valve 41, reliable calibration of the gas alarm with online calibration function can be achieved.

[0059] In this embodiment, preferably, the filter 43 is connected to the normally open port of the control valve 41, and the standard content gas supply mechanism is connected to the normally closed port of the control valve 41.

[0060] When the coil of control valve 41 is not energized, control valve 41 is in a state of being cut off from the standard content gas supply mechanism, and the connection position of filter 43 is in a state of being connected. At this time, since the air pump 42 is not activated, the air in the environment cannot overcome the resistance of filter 43 and cannot enter filter 43. Since the connection position of control valve 41 to the outlet of the standard content gas supply mechanism is in a cut-off state, standard content gas cannot pass through control valve 41. When zero-point calibration is required, the state of control valve 41 is kept unchanged, and the air pump 42 is started to deliver pure gas to the position of sensor probe 3. Subsequently, the control system controls control valve 41 to switch the valve core position so that standard content gas is delivered to the position of sensor probe 3 by air pump 42, thereby realizing the range calibration of the gas alarm with online calibration function.

[0061] Therefore, the control system can control the gas supply system by controlling the control valve 41, so that the calibration process of the gas alarm with online calibration function is carried out according to the design requirements.

[0062] In this embodiment, preferably, the standard content gas supply mechanism is configured as a gas bag 45, which is detachably connected to the control valve 41.

[0063] The gas bag 45 contains a standard content gas, the content of the gas to be measured in the standard content gas is fixed, and the range of the gas alarm with online calibration function is used for calibration.

[0064] The gas bag 45 is configured to be detachably connected to the control valve 41, so that a new gas bag 45 can be replaced after the gas in the gas bag 45 is used up.

[0065] The connection between the gas bag 45 and the control valve 41 is a quick-connect interface. No valves or switches are installed inside the gas bag 45. The seal at the outlet of the gas bag 45 is achieved by the action of the control valve 41. When the coil of the control valve 41 is not energized, the control valve 41 seals the outlet of the gas bag 45. When the coil of the control valve 41 is energized, the control valve 41 opens the outlet of the gas bag 45, allowing the gas inside the gas bag 45 to enter the vacuum pump 42. Therefore, by controlling the control valve 41, automatic calibration of the gas alarm with online calibration function can be achieved without the need for manual opening of the valve on the gas bag 45.

[0066] In this embodiment, preferably, the capacity of the air bag 45 is set to 10-1000ml, and the inflation pressure of the air bag 45 is set to 0.1-0.3Mpa.

[0067] Depending on the available space at the installation location of the gas alarm with online calibration function, a suitable gas bag 45 can be selected. Preferably, the gas bag 45 contains at least the amount of gas required for one calibration.

[0068] The gas pressure inside the gas bag 45 is set to 1-3 atmospheres. After each use of the gas with the specified content, the gas pressure inside the gas bag 45 will decrease. Therefore, a vacuum pump 42 is provided to extract the gas inside the gas bag 45 to ensure the reliability of the calibration work.

[0069] In this embodiment, preferably, a flow limiting valve 46 is also provided between the control valve 41 and the air pump 42.

[0070] By setting the flow limiting valve 46 to control the flow rate of the gas entering the vacuum pump 42, the volume of gas reaching the sensor probe 3 position per unit time is fixed, which reliably ensures the reliability of the calibration work of the gas alarm with online calibration function and ensures the consistency of each calibration.

[0071] In this embodiment, preferably, the filter 43 is filled with an adsorbent material, which can be one or more of activated carbon 201, molecular sieve 202 and silica gel 203.

[0072] The filter tube is filled with adsorbent material, which can be used to fill the entire section or intermittently. For example... Figure 3-5 As shown, the filling sequence of the adsorbent material inside filter 43 can be either a complete section or intermittent sections. Figure 3 The filter 43 shown is filled with activated carbon 201 and molecular sieve 202 in two U-shaped tubes. Figure 4 In the filter 43 shown, activated carbon 201 and molecular sieve 202 are sequentially filled into the U-shaped tube; Figure 5 In the filter 43 shown, activated carbon 201, molecular sieve 202, and silica gel 203 are sequentially filled into the U-shaped tube.

[0073] The filter 43 and the air bag 45 are equipped with a stainless steel protective shell. The protective shell can protect the filter 43 and the air bag 45 from external impacts, thus protecting the filter 43 and the air bag 45.

[0074] This utility model also provides an online calibration method for a gas alarm with online calibration function, including:

[0075] Step 1: Set the calibration time and start the calibration procedure after the calibration time is reached;

[0076] Step 2: Perform zero-point calibration in the calibration procedure;

[0077] Step 3: Perform range calibration in the calibration procedure;

[0078] Step 4: Complete the calibration procedure and set the next calibration time.

[0079] Gas alarms with online calibration functions have a built-in timer that determines the calibration time.

[0080] In one implementation, the timer is configured as a real-time clock (RTC). This independent RTC chip (such as DS1307 or PCF8563) can maintain timing via a backup battery (such as a coin cell battery) even when the main power is off. This RTC can provide accurate year, month, day, hour, minute, and second time data, and ensures that timing is unaffected by device restarts.

[0081] During factory testing or the last calibration, the next maintenance time can be written into the device's non-volatile memory. The control system compares the time of the real-time clock (RTC) with the next maintenance time set in the non-volatile memory. If the comparison finds that the RTC time matches the next maintenance time, the calibration procedure will be started.

[0082] When performing zero-point calibration in the calibration procedure, the control system starts the air pump 42. Under the action of the air pump 42, the air in the environment enters the filter 43 through the inlet end 431 of the filter 43 for filtration. The filtered air is pure air, which is delivered to the vicinity of the sensor probe 3 by the air supply pipe 44. The sensor probe 3 detects the pure air. If the value detected by the sensor probe 3 is not 0, the control system will force the value to be calibrated to 0, thereby realizing the zero-point calibration of the gas alarm with online calibration function.

[0083] After zero-point calibration, the range of the gas alarm with online calibration function needs to be calibrated immediately. This is because after zero-point calibration, the ambient air around sensor probe 3 is expelled, and sensor probe 3 is surrounded by pure air. At this time, introducing standard concentration gas will yield more accurate detection results.

[0084] After zero-point calibration is completed, the control system sends a signal to the control valve 41, energizing the coil of the control valve 41. The valve core of the control valve 41 moves, and the connection between the filter 43 and the control valve 41 is cut off. The connection between the standard content gas supply mechanism and the control valve 41 is then connected to the vacuum pump 42. Under the action of the vacuum pump 42, the standard content gas in the standard content gas supply mechanism is delivered to the vicinity of the sensor probe 3. The sensor probe 3 detects the standard content gas. The control system compares the actual detection result with the value set in the system. If the actual detection result is not equal to the value set in the system, the control system modifies the data of the control circuit of the sensor probe 3, thereby realizing the range calibration of the gas alarm with online calibration function.

[0085] In one embodiment, the gas alarm with online calibration function has the function of detecting oxygen gas. The range of oxygen gas detection by the alarm is 0-30% vol. The standard content gas supply mechanism is filled with 20% vol oxygen standard gas. After the gas alarm with online calibration function is installed on site and operated for a certain period of time, according to the settings of the automatic calibration program, the air pump 42 is turned on to draw air. After being filtered by the filter 43, the clean air reaches the vicinity of the sensor probe 3 of the alarm to complete the zero-point calibration of the alarm. Then, the control valve 41 is turned on to draw oxygen standard gas from the standard content gas supply mechanism to the vicinity of the sensor probe 3, forming a 20% vol oxygen gas environment. The automatic calibration program completes the gas concentration calibration of the alarm by comparing the change of the response value of the sensor probe 3 with the factory setting value.

[0086] In another embodiment, the gas alarm with online calibration function has the function of detecting ammonia gas, which is toxic. The range of ammonia gas detection by the alarm is 0-0.1% vol. The standard content gas supply mechanism is filled with 0.01% vol ammonia standard gas. After the gas alarm with online calibration function is installed on site and operated for a certain period of time, according to the automatic calibration program settings, the air pump 42 is turned on to draw air. After being filtered by the filter 43, the clean air is brought to the vicinity of the sensor probe 3 to complete the zero-point calibration of the alarm. Then, the control valve 41 is turned on to draw standard ammonia gas from the standard content gas supply mechanism and bring it to the vicinity of the sensor probe 3 to form a gas environment of 0.01% vol ammonia. The automatic calibration program completes the gas concentration calibration of the alarm by comparing the change in the response value of the sensor probe 3 with the factory setting value.

[0087] After completing the calibration fixture for the gas alarm with online calibration function, the control system also needs to set the next calibration time so that the timer can start the calibration procedure according to the calibration time.

[0088] In this embodiment, preferably, the gas alarm with online calibration function has a built-in timer that determines the calibration time.

[0089] In one embodiment, the timer is configured as a timer with timing function. At the factory or during the last calibration, the next maintenance time can be written into the timer, for example, 500 hours. The timer then counts down based on the written next calibration time. The control system checks the countdown result of the timer. If the countdown result is 0, the timer will send a signal to the controller. After the controller receives the signal, it will start the calibration procedure.

[0090] In this embodiment, preferably, the calibration environment is judged before step 2 begins. If the environment does not meet the requirements, a stop calibration signal is issued and an alarm system is activated.

[0091] The calibration environment requires a temperature of 0-40℃ and a humidity of 0-90%. Before starting the calibration procedure, the calibration environment needs to be checked. If the environmental conditions are met, the calibration procedure can be executed. If the environmental conditions are not met, the calibration should be abandoned and an alarm signal should be issued.

[0092] In this embodiment, preferably, in steps 2 and 3, the function of the sensor is judged, and if the sensor function is abnormal, a stop calibration signal is issued.

[0093] If the data detected by sensor probe 3 is 0 in the range calibration result, the control system sends an alarm signal to alarm device 2 indicating that sensor probe 3 has failed, and at the same time sends a signal to stop calibration.

[0094] The preferred embodiments of the present invention have been described in detail above with reference to the accompanying drawings. However, the present invention is not limited to the specific details of the above embodiments. Within the scope of the technical concept of the present invention, various simple modifications can be made to the technical solution of the present invention, and these simple modifications all fall within the protection scope of the present invention.

[0095] It should also be noted that the various specific technical features described in the above specific embodiments can be combined in any suitable way without contradiction. In order to avoid unnecessary repetition, this utility model will not describe the various possible combinations separately.

[0096] Furthermore, various different embodiments of this utility model can be combined in any way, as long as they do not violate the spirit of this utility model, they should also be regarded as the content disclosed by this utility model.

Claims

1. A gas alarm with online calibration function, characterized in that, It includes an alarm body (1), an alarm device (2), a gas supply system, and a sensor probe (3) for detecting gas content. The gas supply system is fixedly connected to the alarm body (1) and is used to supply the gas to be tested to the sensor probe (3). The gas supply system includes a pure air supply mechanism for zero-point calibration, a standard content gas supply mechanism for range calibration, and a control valve (41), which is used to switch the gas supplied to the sensor probe (3). The gas alarm with online calibration function also includes a control system, which is electrically connected to the control valve (41), sensor probe (3) and alarm device (2) to control the action of the control valve (41) and control the alarm device (2) to issue an alarm.

2. The gas alarm with online calibration function according to claim 1, characterized in that, The clean air supply mechanism includes an air pump (42), a filter (43), and an air supply pipe (44), the outlet of which faces the sensor probe (3).

3. The gas alarm with online calibration function according to claim 2, characterized in that, The inlet end (431) of the filter (43) is open to the environment, and a certain amount of standard content gas is stored in the standard content gas supply unit.

4. The gas alarm with online calibration function according to claim 2, characterized in that, The control valve (41) is set as a two-position three-way valve. The two valve core positions of the control valve (41) correspond to the connection of pure air to the air pump (42) and the connection of standard content gas to the air pump (42), respectively.

5. The gas alarm with online calibration function according to claim 3, characterized in that, The filter (43) is connected to the normally open port of the control valve (41), and the standard content gas supply mechanism is connected to the normally closed port of the control valve (41).

6. The gas alarm with online calibration function according to claim 3, characterized in that, The standard content gas supply mechanism is configured as a gas bag (45), which is detachably connected to the control valve (41).

7. The gas alarm with online calibration function according to claim 6, characterized in that, The capacity of the air bag (45) is set to 10-1000ml, and the inflation pressure of the air bag (45) is set to 0.1-0.3Mpa.

8. The gas alarm with online calibration function according to claim 2, characterized in that, A flow limiting valve (46) is also provided between the control valve (41) and the air pump (42).

9. The gas alarm with online calibration function according to claim 2, characterized in that, The filter (43) is filled with adsorbent material, which can be one or more of activated carbon (201), molecular sieve (202) and silica gel (203).

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