On site, there are usually some problems, such as wrong installation direction of the airtight valve at the exhaust outlet and falling of the name plate
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The installation of explosion-proof overpressure exhaust valve and automatic exhaust valve shall ensure that the opening direction of the valve must be towards the exhaust direction, the valve can be opened and closed flexibly, and the valve disc and sealing ring are closely connected after closing
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Prevention and control measures: the overpressure piezometer pipe of civil air defense project is a dn 15 galvanized steel pipe, which should be directly embedded in the roof concrete
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Prevention and control measures: piezometric tube and sampling tube are necessary facilities for ventilation in civil air defense engineering in wartime
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The two ends of the pipe should be vertical and downward, and the reserved positions at both ends should be accurate
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If the air duct is used in wartime, the airtight short pipe shall be embedded in the air wall and airtight wall at the entrance and exit of civil air defense
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Analysis: in order to prevent toxic substances from entering the engineering cleaning area through the ventilation pipeline, the pipeline and accessories from a closed valve in the cleaning area to the wave elimination valve shall be made of 3mm thick fully welded steel plate air pipe, and the welding seam shall be full, uniform and tight, and the thin galvanized steel plate with general bite connection shall not be used
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At the same time, the closed valve shall be fixed by hook or bracket, and the hook shall not be hung at the handle or locking position.
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If the concrete holes are not reserved according to the relevant regulations, the effective protective sealing treatment can not be carried out afterwards according to the specification requirements
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Special elbows should be used at the turning of the pipeline, and the distance between the pipe orifices at both ends and the wall and roof should not be less than 100 mm
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Analysis: during the installation of ventilation closed valve, the arrow marking the pressure path should be consistent with the direction of shock wave
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The installation of automatic exhaust valve and explosion-proof overpressure exhaust valve is the same, but it is connected with the explosion-proof overpressure exhaust valve, which is a full welded steel air pipe with the thickness of 6mm
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Table 1 d4oj-0.5 manual airtight valve embedded pipe outer diameter (unit mm) table 2 automatic exhaust valve, explosion-proof wave overpressure exhaust valve embedded pipe inner diameter, spacing (unit mm) 05 common problems five phenomena: clean ventilation, filter ventilation system is not set two airtight, or two airtight are set in the poisoning area
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When Binding civil steel bars, they should be properly reserved and embedded in place according to professional drawings
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All connecting flanges on the welded air duct shall be made of car flange with sealing groove and thickness of 8 mm
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As shown in the figure, when only one anti-virus channel is set in the exhaust system, automatic exhaust valve or explosion overpressure exhaust valve shall be set in the clean area
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Four common faults: the diameter of pipeline and embedded through wall pipe does not match the diameter of connecting pipe of connected pipeline or manually sealed valve
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Common fault of civil air defense engineering construction quality 01 common fault one phenomenon: when the air duct passes through the free wall, closed wall and floor, the concrete hole is reserved at will
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The flange gasket shall be single-layer, whole ring without interface, and plate rubber sealing ring with thickness of 4 mm, so as to achieve the necessary strength and sealing requirements
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Prevention measures: when installing the automatic exhaust valve and (explosion-proof) overpressure exhaust valve, judge whether the installation is correct by the position of the heavy hammer
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The position of the heavy hammer should be at the lowest position (because the overpressure in the room is adjusted by the heavy hammer
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Prevention and control measures: the first airtight valve should be set in the contaminated area and the second airtight valve should be set in the clean area
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Prevention and control measures: pay attention to the installation position of the closed valve to facilitate the operation of the valve handle and meet the normal rotation of the handle
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On the clean pipeline, a sampling pipe should be set between the two closed valves, before and after the filter
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09 common fault 9 phenomenon: ventilation airtight valve installation is not in accordance with the specification requirements
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Seven common problems: there is no side pressure pipe, sampling pipe or wrong position on the air supply system of the personnel masking department with poison filtering ventilation
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Because the shock wave always flows from the outside to the inside along the pipe, the direction of the valve arrow of the air inlet system is the same as that of the air flow, and the direction of the valve arrow of the air exhaust system is opposite to that of the air flow
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Six common problems: ventilation pipes with protective sealing function requirements, wrong materials and construction technology
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Analysis: in some ventilation construction drawings, the nominal diameter, such as dn300400, is used to mark the diameter of inlet and outlet air pipes (circular air pipes) in civil air defense war It is marked according to the nominal diameter of the equipment such as manual closed valve installed in the pipeline, and the diameter of the pipeline and embedded through wall pipe shall be consistent with the connecting pipe diameter of the connected pipeline or manual closed valve, automatic exhaust valve (YF type, PS type) and explosion-proof overpressure exhaust valve (FCS type)
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The thickness of the steel plate shall not be less than 10 mm, and the angle steel can be ∟ 80 × 80 × 8 mm
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Analysis: pressure measuring pipe should be set at the inlet and outlet of the filter and the filter absorber, and the sampling pipe for measuring the gas concentration should be set on the connecting pipe
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The indoor end should be set in the duty room or fan room, and the outdoor short end should be set outside the protective airtight door or outside the diffusion chamber and valve, which is directly the same as the atmosphere
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Analysis: when the civil air defense project is used as the personnel shelter department, in order to ensure that the contaminated substances do not enter the clean area, the air inlet and exhaust systems of clean ventilation and poison filtration ventilation in the air defense basement are sealed
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Through the resistance change of the dust filter and the filter absorber, the dust and poison filtering capacity can be mastered in time (Fig
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The flange contact surface shall be flat
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The indoor end shall be twisted with screw thread and bunched
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Prevention and control measures: in order to facilitate the full ventilation of the anti-virus channel or decontamination room, the automatic exhaust valve, explosion-proof overpressure exhaust valve and related short ventilation pipe or closed valve shall be staggered in the horizontal and vertical directions
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According to the specification requirements, the steel plate air duct must be set with two sealed valves, and the last sealed valve must be set in the clean area, such as the air inlet system in the fan room
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In order to measure the difference between indoor and outdoor pressure, overpressure pressure measuring device should be set
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Eight common problems: automatic exhaust valve, (explosion-proof) overpressure exhaust valve is not installed according to the specification
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There is no such requirement in some construction drawings, or piezometric tube and sampling tube are missing, and the setting position is incorrect
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The first airtight valve is set in front of the filter absorber and the second airtight valve is set in the clean area
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03 three common problems: when the civil air defense fortifications are used as personnel shelter, the fortifications are not equipped with overpressure piezometers, or the outdoor end is set in the diffusion room, and the indoor end is set in the poison filtering room, or the two ends are not out of the roof
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Prevention and control measures: if the air duct is used in peacetime, steel plate or angle iron frame shall be embedded around the hole for temporary plugging
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31)
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Analysis: when installing the automatic exhaust valve, (explosion-proof) overpressure exhaust valve, it must ensure that the flange surface of the through wall pipe and the lever on the axis line of sight are vertical, and the position of the inner retaining ring of the (explosion-proof) overpressure exhaust valve is correct and cannot be inverted
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Analysis: all pipelines passing through the above walls should be protected and sealed according to the specification requirements, which is the basic requirement and key content of the civil air defense engineering construction and acceptance specification
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Preventive measures: see Table 1 for the outer diameter of the embedded pipe, and table 2 for the inner diameter and spacing of the embedded pipe
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If the short pipe embedded in the free wall and airtight wall is used as sleeve, the shock wave and poison will easily enter into the civil air defense project
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Prevention and control measures: Wartime welding air pipe and its flange manufacturing method: Wartime welding air pipe refers to the air pipe part with sealing requirements, generally refers to the airtight valve part from the mouth of the project to the inner side of the project, which shall be welded by steel plate with thickness of 3mm
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The second common problem is that the automatic exhaust valve and related short ventilation pipe or closed valve are not staggered in the horizontal and vertical directions
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The pressure measuring pipe and sampling pipe should be made at the same time as the air pipe
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If the project is not equipped with overpressure pressure measuring tube or the outdoor end is in the diffusion room, the indoor end is set in the poison filtering room or both ends It’s a mistake if it doesn’t come out
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When the overpressure in the room disappears, the valve is closed by the heavy hammer, so the position of the heavy hammer should be at the lowest position)
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Analysis: when the civil air defense project is used as a personnel shelter, in order to prevent the entry of external toxic gases or radioactive agents into the project, the project should maintain an overpressure of 30-50pa
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