There are dangerous explosive gases or dust in the working environment of chemical industry, petroleum, coal and other industries. Therefore, it is very necessary to install explosion-proof cameras to ensure a safe environment for industrial production, which is the main significance of the existence of explosion-proof monitoring cameras.  At present, factories are paying more and more attention to production safety, and the requirements for work efficiency are also getting higher and higher. In order to improve production safety, improve production efficiency, and make rational use of human resources, explosion-proof cameras have played a great role. Today, I would like to briefly introduce to you the relevant knowledge of explosion-proof monitoring equipment.  First, the principle of how to select explosion-proof cameras for explosion-proof monitoring lenses is the same as that of ordinary cameras, with 4-25mm lenses available.  It is mainly based on the distance and range to be monitored at the scene to select the appropriate lens.  For example, if the monitored object is about 30 meters away from the installation point, then a 12mm or 16mm lens should be selected.  If you want to see more clearly, choose a 16mm lens, blur it, and choose a 12mm lens.  In fact, the lens has a theoretical length value. The number of millimeters of the lens multiplied by 2 equals the distance of the object to be measured.  The defect of the lens is that it looks wide but not far, and looks far but not wide.  The smaller the number of millimeters of the lens, the larger the range, whereas the shorter the distance.  2. Installation of explosion-proof camera 1. Under the condition of meeting the requirements of monitoring target's field of view, its installation height: the installation height of indoor camera should be 2.5 ~ 5m, and that of outdoor camera should be 3.5～10m;  The elevator car is installed at the top of the car at a diagonal angle to the elevator operator, and the optical axis of the camera is 45 degrees to the two walls and ceiling of the elevator.  2. The camera and its supporting devices shall be protected from damage and coordinated with the surrounding environment.  3. In the environment of strong electromagnetic interference, the camera installation should be insulated from the ground.  4. Lightning protection measures shall be taken for outdoor installation.  5. The camera must be firmly installed to prevent the monitor screen from shaking.  6. Commissioning of infrared lamp must be carried out at night.  At night, the illumination position of the infrared beam is adjusted by imaging equipment (such as a monitor, etc.).  And can effectively adjust the setting of the lens aperture.  7. The installation height of infrared lamp should not exceed 4 meters, which will affect the reflectivity of light.  The angle should be 20 degrees from top to bottom, and the reflectivity will be reduced if the elevation angle is too large.  8. Infrared camera, try to avoid direct light source, because the infrared lamp power control part is based on the photosensitive resistor installed on the infrared lamp board to control the infrared lamp power on or off.  9. In the field of view of the infrared camera, all black objects, empty places, water and other objects that absorb infrared light should be avoided as far as possible. The infrared lamp matched with the ccd camera reflects the infrared light on the object onto the lens of the ccd camera to form an image. If the infrared light is absorbed or weakened, the effective irradiation effect of the infrared lamp will be greatly weakened. 10. The working index of infrared lamp (see the product specification for details) must be guaranteed. For example, the power supply power of infrared lamp must be higher than the working power of the infrared lamp itself.  11. Users should read the operating instructions carefully before using infrared lamps, especially the precautions to ensure personal and equipment safety.  Check whether the matching aspects described above meet the requirements, and whether the influencing factors that should be considered are taken into account. If the requirements are not met, the equipment used can be adjusted in time.  12. Be careful not to touch the lens and ccd target surface with your hands and not to let dust float on the camera during installation.  13. Installation of Yuntai: 1) The installation of Yuntai shall be firm without shaking when rotating.  2) According to the product technical conditions and system design requirements, check whether the rotation angle range of Yuntai meets the requirements.  3) Decoder shall be installed near Yuntai or in ceiling (but with access holes).  14. Avoid exposure of equipment to large motors such as elevators, water pumps, fluorescent columns, and various high-power radio equipment environments.  15. Choose a good bnc head, this is very critical, bad bnc head will make you die, it is not exaggerated.  3. Installation of line parts 1. Video line: syv75-3 video line generally transmits within 300 meters, 75-5 transmission within 500 meters and 75-7 transmission within 800 meters;  In addition, attention should be paid to the quality of cctv coaxial cable. rg59u, rg6 and rg11 all require 100% copper core and 95% copper braided shield.  The maximum resistance of the circuit loop connection shall not exceed 15 ohms.  When the distance exceeds 500 meters, optical cable transmission should be considered.  2. Power cord: flame-retardant cable should be selected, and the protective cover is relatively strong. On the premise of saving engineering cost, coarser ones should be used as much as possible to reduce the attenuation of power supply.  3. Control line: Generally, cables with shielding 2*1.0 and rvvp2*1.0 are selected.  4. Threading pipe: pvc pipe is usually enough. Galvanized steel pipe should be used for the project of burying or explosion prevention in key areas.  Four, control equipment installation 1. Console, cabinet (frame) installation location should comply with the design requirements, installation should be smooth and firm, easy to operate and maintain.  The net distance between the back and side of the cabinet rack and the wall shall meet the maintenance requirements.  2. Installation of all control, display, recording and other terminal equipment shall be smooth and easy to operate.  Among them, the monitor (screen) should avoid direct external light, and when it is unavoidable, measures should be taken to avoid light.  The equipment installed in the console and cabinet (rack) shall have ventilation and heat dissipation measures, and the internal connectors shall be firmly connected with the equipment.  3. All cables in the control room shall be provided with cable troughs and wire inlet holes according to the installation position of the equipment, arranged and bundled neatly, numbered and permanently marked.  4. The equipment for controlling the working environment and security system of the equipment shall be installed in a clean air conditioning room and shall be installed on a 19 "standard rack. Appropriate space shall be reserved between the equipment and forced ventilation fans shall be used.  5. Ensure that the live wire, zero wire and ground wire of the monitoring indoor power supply are connected in accordance with specifications.  With the monitoring center equipment (monitor, hard disk video recorder, matrix, video distributor) turned on, use analog multimeter AC voltage profile to measure the ground voltage of the above equipment housing and the video cable connector connected to the camera.  The higher the voltage, the more likely it is to cause damage to the video output part of the camera.  When the voltage is not zero, live unplugging of the video cable should be avoided.  Five, installation precautions: 1, installation of explosion-proof camera should pay attention to its installation location: should choose to avoid strong light installation, in need of wide dynamic is higher or when the camera is fuzzy.  2, according to the camera's own performance to choose installation, such as white light to complete the night vision monitoring effect, it is best to choose to install in a dark light and it is necessary to install.  3. For a camera without infrared function, it needs to be installed in a bright place.  4. Cables should be concealed as much as possible.  5. In case of interference, attention should be paid to strengthening the installation method to prevent the image from blurring.  Six, some matters needing attention in equipment maintenance in the process of maintenance of explosion-proof monitoring system equipment, should take precautions against some situations, as far as possible to make the normal operation of the equipment, mainly need to do a good job of moistureproof, dustproof, anticorrosive, lightning protection, anti interference.  1, moistureproof, dustproof, anticorrosive for explosion-proof monitoring system of various collection equipment, because the equipment directly placed in a dusty environment, will have a direct impact on the operation of explosion-proof equipment, need to focus on moistureproof, dustproof, anticorrosive maintenance work.  If the explosion-proof camera is hung at the shed end for a long time, the explosion-proof shield and the explosion-proof glass will soon be covered with a layer of mixture of dust, carbon ash and the like, which is dirty and black and corrosive, seriously affecting the viewing effect and causing damage to the explosion-proof equipment. Therefore, the dust-proof and anti-corrosion maintenance work of the explosion-proof camera must be done well.  In some places with heavy moisture, the installation position and protection of the equipment must be adjusted during maintenance to improve the moisture-proof capability of the equipment itself. At the same time, dehumidification measures should be taken frequently to solve the moisture-proof problem in high humidity areas.  2, lightning protection, anti-interference as long as people who have been engaged in the maintenance of mechanical and electrical systems know, thunderstorms, explosion-proof equipment by lightning is common, to the normal operation of explosion-proof monitoring equipment caused great security risks, therefore, explosion-proof monitoring equipment in the maintenance process must attach great importance to the problem of lightning protection.  Lightning protection measures are mainly to do a good job in the lightning protection grounding network for equipment grounding. An independent comprehensive grounding network with a grounding resistance of less than 1 ohm should be done according to the equipotential body scheme, and the method of mixing the lightning protection grounding of weak current system with the lightning protection grounding network of electric power should be eliminated, so as to prevent the clutter of the grounding network of electric power from interfering with the equipment.  Anti-interference is mainly to adhere to the principle of separation of strong and weak current when wiring, to separate power cables from communication cables and video cables, and to strictly follow the wiring specifications of the communication and power industries.  Seven, simple fault handling 1, explosion-proof monitoring how can't see the image?  First, check whether there is any problem with the imaging of the camera. If there is no problem with the imaging, please check the power supply of the camera.  If the power supply is normal, check the transmission equipment of the camera (such as optical transceiver, etc.);  If the transmission equipment is good, check the connector of the transmission line again.  If the connector of the transmission cable is good, check the transmission cable again.  If there is no problem with the transmission cable, check the signal access equipment again.  If the signal access equipment is good, check whether the system settings of the signal access equipment are correct.  2, explosion-proof camera image blur may be lens focal length is not adjusted;  Oil stain or dust on glass, lens or ccd;  If it is blurred at night, some manufacturers will not be good at infrared at night in order to save costs and design defects, because the infrared lamp is too close to the lens, causing reflection, and the infrared lamp is too close to the lens camera.  3. The explosion-proof camera is installed at the scene. Why is there no image?  Check whether the power supply of explosion-proof camera is connected properly and whether the power supply voltage meets the requirements;  Whether bnc head or video cable is in good contact;  If you use a manual aperture lens, check whether the aperture is open, and adjust the automatic aperture lens.  Section level potentiometer makes the aperture in the appropriate position.