Summary of practical knowledge on explosion-proof monitoring equipment
2024-4-11 View：
There are dangerous explosive gases or dust in the working environment of chemical, petroleum, coal and other industries. Therefore, it is very necessary to install explosion-proof cameras. Ensuring the safe environment of industrial production is the main purpose of the existence of explosion-proof surveillance cameras. Nowadays, factories pay more and more attention to production safety, and the requirements for work efficiency are also getting higher and higher. Factories must improve production safety, improve production efficiency, and rationally utilize human resources. Explosion-proof cameras play a big role. Today Let me briefly introduce the relevant knowledge of explosion-proof monitoring equipment.
1. How to choose explosion-proof surveillance lenses
The principle of lens selection for explosion-proof cameras is the same as that of ordinary cameras, with 4-25MM lenses available. The appropriate lens is selected mainly based on the distance and range to be monitored at the scene. 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 clearly, choose a 16MM lens, and if you want to see something blurry, choose a 12MM lens. In fact, the lens has a theoretical length value. The number of millimeters of the lens multiplied by 2 is equal to the distance of the object being measured. The shortcoming of the lens is that it can see the width but not the distance, and it can see the distance but not the width. The smaller the lens millimeters, the wider the range, and conversely the shorter the distance.
2. Installation of explosion-proof cameras
1. Under the condition that the field of view range of the surveillance target is met, its installation height: the installation height of the indoor camera is preferably 2.5 to 5m, and the outdoor camera is 3.5 to 10m; it is installed on the top of the elevator car and is in conjunction with the elevator operation. The camera is at a diagonal position, and the optical axis of the camera is at 45 degrees to the two walls and ceiling of the elevator.
2. The camera and its supporting devices should be protected from damage and coordinated with the surrounding environment.
3. In an environment with strong electromagnetic interference, the camera installation should be insulated from the ground.
4. Lightning protection measures must be taken for outdoor installation.
5. The camera must be installed firmly to prevent the surveillance picture from shaking.
6. Debugging of infrared lights must be done at night. Adjust the infrared beam illumination position through imaging equipment (such as monitors, etc.) at night. And can effectively adjust the lens aperture settings.
7. The installation height of infrared lamps should not exceed 4 meters. Too high will affect the reflectivity of light. The ideal angle should be 20 degrees from top to bottom. If the elevation angle is too large, the reflectivity will decrease.
8. For infrared cameras, try to avoid direct light sources, because the power control part of the infrared light controls whether the working power of the infrared light is turned on or off based on the photoresistor installed on the infrared light board.
9. Try to avoid completely black objects, open spaces, water and other objects that absorb infrared light in the field of view of the infrared camera. The infrared light matched with the CCD camera relies on emitting infrared light and reflecting it on the object to form an image on the CCD camera lens. If Absorption or weakening of infrared light will greatly weaken the effective irradiation effect of infrared lamps.
10. The working indicators of the infrared lamp must be guaranteed (see the product manual for details). For example, the power supply power of the infrared lamp must be higher than the working power of the infrared lamp itself.
11. When using infrared lights, users must first read the instruction manual carefully, especially the precautions to ensure the safety of personal equipment. Check whether the matching requirements described above are met 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. During the installation process, be careful not to touch the lens or CCD target surface with your hands, and do not let dust float to the camera.
13. Installation of PTZ:
1) The installation of the gimbal should be firm and there should be no shaking when rotating.
2) Check whether the rotation angle range of the gimbal meets the requirements based on product technical conditions and system design requirements.
3) The decoder should be installed near the pan/tilt or in the ceiling (but a manhole must be left).
14. Avoid exposing the equipment to large motors such as elevators, water pumps and fluorescent columns, as well as various high-power radio equipment.
15. Choosing a good BNC head is very important. A bad BNC head will make your life worse than death. It is no exaggeration at all.
3. Installation of line parts
1. Video cable: The video cable of SYV75-3 generally transmits within 300 meters, the video cable of 75-5 can transmit within 500 meters, and the video cable of 75-7 can transmit 800 meters; another thing to pay attention to is the quality of CCTV coaxial cable, RG59U, RG6 Both RG11 and RG11 require 100% copper core and 95% copper braided shielding. The maximum resistance of the line loop cannot exceed 15 ohms. When the distance exceeds 500 meters, optical cable transmission must be considered.
2. Power cord: You should choose a flame-retardant cable with a relatively strong protective sheath. On the premise of saving engineering costs, try to use a thicker cable to reduce the attenuation of the power supply.
3. Control line: Generally use shielded 2*1.0 cable, RVVP2*1.0.
4. Threading pipe: Generally, PVC pipes can be used. Galvanized steel pipes should be used for underground or explosion-proof projects.
4. Installation of control equipment
1. The installation position of the console and cabinet (rack) should meet the design requirements, and the installation should be stable and firm, and easy to operate and maintain. The clear distance between the back and sides of the cabinet rack and the wall should meet maintenance requirements.
2. The installation of all control, display, recording and other terminal equipment should be stable and easy to operate. The monitor (screen) should avoid direct exposure to external light. When unavoidable, measures should be taken to avoid light. Equipment installed in consoles and cabinets (racks) should have ventilation and heat dissipation measures, and internal connectors and equipment should be firmly connected.
3. All cables in the control room should be provided with cable troughs and cable entry holes according to the installation location of the equipment, neatly arranged, bundled, numbered, and permanently marked.
4. The equipment of the working environment security system that controls the equipment is required to be installed in a clean air-conditioned room and on a 19" standard rack. Appropriate space should be left between the equipment and forced ventilation fans must be used.
5. Ensure that the live wire, neutral wire, and ground wire of the power supply in the monitoring room are connected according to specifications. When the monitoring center equipment (monitor, hard disk recorder, matrix, video distributor) is turned on, use an analog multimeter at the AC voltage range to measure the ground voltage of the above equipment shell and the video cable connector connected to the camera. The higher the voltage, the more likely it is to damage the video output part of the camera. When the voltage is not zero, avoid unplugging and plugging video cables while power is on.
5. Installation precautions:
1. When installing an explosion-proof camera, attention should be paid to its installation location: it should be installed in a place away from strong light, which is useful when high dynamic range is required or when the camera is blurry.
2. The installation should be selected based on the performance of the camera itself. For example, if the night vision monitoring effect is achieved by white light, it is best to install it in a dark and necessary place.
3. For cameras without infrared functions, they need to be installed in a brighter environment.
4. Cables should be routed through hidden pipes as much as possible.
5. When encountering interference, you need to pay attention to strengthening the installation method to prevent the image from blurring.
6. Some precautions in equipment maintenance
During the maintenance of explosion-proof monitoring system equipment, some situations should be prevented to ensure the normal operation of the equipment as much as possible. It is mainly necessary to do a good job of moisture-proof, dust-proof, anti-corrosion, lightning protection, and anti-interference work.
1. Moisture-proof, dust-proof and anti-corrosion
For various collection equipment of the explosion-proof monitoring system, since the equipment is placed directly in a dusty environment, it will have a direct impact on the operation of the explosion-proof equipment, so it is necessary to focus on moisture-proof, dust-proof, and anti-corrosion maintenance. If an explosion-proof camera is hung at the end of the shed for a long time, the explosion-proof shield and explosion-proof glass will soon be covered with a layer of dust, carbon ash, etc., which is dirty, black, and corrosive, seriously affecting the viewing effect and also causing damage to the explosion-proof camera. The equipment will cause damage, so dust-proof and anti-corrosion maintenance work must be done for the explosion-proof camera. In some places with heavy humidity, the installation location and equipment protection must be adjusted during the maintenance process to improve the moisture-proof ability of the equipment itself. At the same time, dehumidification measures must be taken frequently in high-humidity areas to solve the moisture-proof problem.
2. Lightning protection and interference prevention
Anyone who has been engaged in the maintenance of electromechanical systems knows that it is common for explosion-proof equipment to be struck by lightning during thunderstorms, which poses a great safety hazard to the normal operation of explosion-proof monitoring equipment. Therefore, explosion-proof monitoring equipment must be properly inspected during the maintenance process. We attach great importance to the issue of lightning protection. The main measures for lightning protection are to build a lightning protection ground network for grounding equipment. An independent comprehensive grounding network with a ground resistance of less than 1 ohm should be prepared according to the equipotential body scheme to eliminate the lightning protection grounding of weak current systems and the electric lightning protection grounding network. The method of mixing together is to prevent the power grounding network clutter from interfering with the equipment. To prevent interference, we should adhere to the principle of separation of strong and weak electricity during wiring, separate power cables from communication cables and video cables, and strictly follow the wiring specifications of the communication and power industries.
7. Simple troubleshooting
1. Why can’t I see the image on the explosion-proof surveillance camera?
First check whether there is any problem with the camera's imaging. If there is no problem with the imaging, please check the camera's power supply;
If the power supply is normal, check the camera’s transmission equipment (such as optical transceiver, etc.);
If the transmission equipment is good, check the connectors of the transmission line;
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 device;
If the signal access device is good, check whether the system settings of the signal access device are correct.
2. The image of the explosion-proof camera is blurry
It is possible that the lens focus is not adjusted correctly;
There is oil or dust on the glass, lens or CCD;
If it is blurry at night, in order to save costs, some manufacturers have design flaws. The infrared light is too close to the lens, causing reflection, and the infrared light is too close to the lens. These types of products will not have good infrared at night.
3. The explosion-proof camera is installed at the scene, why is there no image?
Check whether the power supply of the explosion-proof camera is connected properly and whether the power supply voltage meets the requirements;
Whether the BNC connector or video cable is in good contact;
If you use a manual aperture lens, you need to check whether the aperture is open. If you use an automatic aperture lens, you need to adjust the LEVEL potentiometer to make the aperture at the appropriate position.
1. How to choose explosion-proof surveillance lenses
The principle of lens selection for explosion-proof cameras is the same as that of ordinary cameras, with 4-25MM lenses available. The appropriate lens is selected mainly based on the distance and range to be monitored at the scene. 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 clearly, choose a 16MM lens, and if you want to see something blurry, choose a 12MM lens. In fact, the lens has a theoretical length value. The number of millimeters of the lens multiplied by 2 is equal to the distance of the object being measured. The shortcoming of the lens is that it can see the width but not the distance, and it can see the distance but not the width. The smaller the lens millimeters, the wider the range, and conversely the shorter the distance.
2. Installation of explosion-proof cameras
1. Under the condition that the field of view range of the surveillance target is met, its installation height: the installation height of the indoor camera is preferably 2.5 to 5m, and the outdoor camera is 3.5 to 10m; it is installed on the top of the elevator car and is in conjunction with the elevator operation. The camera is at a diagonal position, and the optical axis of the camera is at 45 degrees to the two walls and ceiling of the elevator.
2. The camera and its supporting devices should be protected from damage and coordinated with the surrounding environment.
3. In an environment with strong electromagnetic interference, the camera installation should be insulated from the ground.
4. Lightning protection measures must be taken for outdoor installation.
5. The camera must be installed firmly to prevent the surveillance picture from shaking.
6. Debugging of infrared lights must be done at night. Adjust the infrared beam illumination position through imaging equipment (such as monitors, etc.) at night. And can effectively adjust the lens aperture settings.
7. The installation height of infrared lamps should not exceed 4 meters. Too high will affect the reflectivity of light. The ideal angle should be 20 degrees from top to bottom. If the elevation angle is too large, the reflectivity will decrease.
8. For infrared cameras, try to avoid direct light sources, because the power control part of the infrared light controls whether the working power of the infrared light is turned on or off based on the photoresistor installed on the infrared light board.
9. Try to avoid completely black objects, open spaces, water and other objects that absorb infrared light in the field of view of the infrared camera. The infrared light matched with the CCD camera relies on emitting infrared light and reflecting it on the object to form an image on the CCD camera lens. If Absorption or weakening of infrared light will greatly weaken the effective irradiation effect of infrared lamps.
10. The working indicators of the infrared lamp must be guaranteed (see the product manual for details). For example, the power supply power of the infrared lamp must be higher than the working power of the infrared lamp itself.
11. When using infrared lights, users must first read the instruction manual carefully, especially the precautions to ensure the safety of personal equipment. Check whether the matching requirements described above are met 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. During the installation process, be careful not to touch the lens or CCD target surface with your hands, and do not let dust float to the camera.
13. Installation of PTZ:
1) The installation of the gimbal should be firm and there should be no shaking when rotating.
2) Check whether the rotation angle range of the gimbal meets the requirements based on product technical conditions and system design requirements.
3) The decoder should be installed near the pan/tilt or in the ceiling (but a manhole must be left).
14. Avoid exposing the equipment to large motors such as elevators, water pumps and fluorescent columns, as well as various high-power radio equipment.
15. Choosing a good BNC head is very important. A bad BNC head will make your life worse than death. It is no exaggeration at all.
3. Installation of line parts
1. Video cable: The video cable of SYV75-3 generally transmits within 300 meters, the video cable of 75-5 can transmit within 500 meters, and the video cable of 75-7 can transmit 800 meters; another thing to pay attention to is the quality of CCTV coaxial cable, RG59U, RG6 Both RG11 and RG11 require 100% copper core and 95% copper braided shielding. The maximum resistance of the line loop cannot exceed 15 ohms. When the distance exceeds 500 meters, optical cable transmission must be considered.
2. Power cord: You should choose a flame-retardant cable with a relatively strong protective sheath. On the premise of saving engineering costs, try to use a thicker cable to reduce the attenuation of the power supply.
3. Control line: Generally use shielded 2*1.0 cable, RVVP2*1.0.
4. Threading pipe: Generally, PVC pipes can be used. Galvanized steel pipes should be used for underground or explosion-proof projects.
4. Installation of control equipment
1. The installation position of the console and cabinet (rack) should meet the design requirements, and the installation should be stable and firm, and easy to operate and maintain. The clear distance between the back and sides of the cabinet rack and the wall should meet maintenance requirements.
2. The installation of all control, display, recording and other terminal equipment should be stable and easy to operate. The monitor (screen) should avoid direct exposure to external light. When unavoidable, measures should be taken to avoid light. Equipment installed in consoles and cabinets (racks) should have ventilation and heat dissipation measures, and internal connectors and equipment should be firmly connected.
3. All cables in the control room should be provided with cable troughs and cable entry holes according to the installation location of the equipment, neatly arranged, bundled, numbered, and permanently marked.
4. The equipment of the working environment security system that controls the equipment is required to be installed in a clean air-conditioned room and on a 19" standard rack. Appropriate space should be left between the equipment and forced ventilation fans must be used.
5. Ensure that the live wire, neutral wire, and ground wire of the power supply in the monitoring room are connected according to specifications. When the monitoring center equipment (monitor, hard disk recorder, matrix, video distributor) is turned on, use an analog multimeter at the AC voltage range to measure the ground voltage of the above equipment shell and the video cable connector connected to the camera. The higher the voltage, the more likely it is to damage the video output part of the camera. When the voltage is not zero, avoid unplugging and plugging video cables while power is on.
5. Installation precautions:
1. When installing an explosion-proof camera, attention should be paid to its installation location: it should be installed in a place away from strong light, which is useful when high dynamic range is required or when the camera is blurry.
2. The installation should be selected based on the performance of the camera itself. For example, if the night vision monitoring effect is achieved by white light, it is best to install it in a dark and necessary place.
3. For cameras without infrared functions, they need to be installed in a brighter environment.
4. Cables should be routed through hidden pipes as much as possible.
5. When encountering interference, you need to pay attention to strengthening the installation method to prevent the image from blurring.
6. Some precautions in equipment maintenance
During the maintenance of explosion-proof monitoring system equipment, some situations should be prevented to ensure the normal operation of the equipment as much as possible. It is mainly necessary to do a good job of moisture-proof, dust-proof, anti-corrosion, lightning protection, and anti-interference work.
1. Moisture-proof, dust-proof and anti-corrosion
For various collection equipment of the explosion-proof monitoring system, since the equipment is placed directly in a dusty environment, it will have a direct impact on the operation of the explosion-proof equipment, so it is necessary to focus on moisture-proof, dust-proof, and anti-corrosion maintenance. If an explosion-proof camera is hung at the end of the shed for a long time, the explosion-proof shield and explosion-proof glass will soon be covered with a layer of dust, carbon ash, etc., which is dirty, black, and corrosive, seriously affecting the viewing effect and also causing damage to the explosion-proof camera. The equipment will cause damage, so dust-proof and anti-corrosion maintenance work must be done for the explosion-proof camera. In some places with heavy humidity, the installation location and equipment protection must be adjusted during the maintenance process to improve the moisture-proof ability of the equipment itself. At the same time, dehumidification measures must be taken frequently in high-humidity areas to solve the moisture-proof problem.
2. Lightning protection and interference prevention
Anyone who has been engaged in the maintenance of electromechanical systems knows that it is common for explosion-proof equipment to be struck by lightning during thunderstorms, which poses a great safety hazard to the normal operation of explosion-proof monitoring equipment. Therefore, explosion-proof monitoring equipment must be properly inspected during the maintenance process. We attach great importance to the issue of lightning protection. The main measures for lightning protection are to build a lightning protection ground network for grounding equipment. An independent comprehensive grounding network with a ground resistance of less than 1 ohm should be prepared according to the equipotential body scheme to eliminate the lightning protection grounding of weak current systems and the electric lightning protection grounding network. The method of mixing together is to prevent the power grounding network clutter from interfering with the equipment. To prevent interference, we should adhere to the principle of separation of strong and weak electricity during wiring, separate power cables from communication cables and video cables, and strictly follow the wiring specifications of the communication and power industries.
7. Simple troubleshooting
1. Why can’t I see the image on the explosion-proof surveillance camera?
First check whether there is any problem with the camera's imaging. If there is no problem with the imaging, please check the camera's power supply;
If the power supply is normal, check the camera’s transmission equipment (such as optical transceiver, etc.);
If the transmission equipment is good, check the connectors of the transmission line;
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 device;
If the signal access device is good, check whether the system settings of the signal access device are correct.
2. The image of the explosion-proof camera is blurry
It is possible that the lens focus is not adjusted correctly;
There is oil or dust on the glass, lens or CCD;
If it is blurry at night, in order to save costs, some manufacturers have design flaws. The infrared light is too close to the lens, causing reflection, and the infrared light is too close to the lens. These types of products will not have good infrared at night.
3. The explosion-proof camera is installed at the scene, why is there no image?
Check whether the power supply of the explosion-proof camera is connected properly and whether the power supply voltage meets the requirements;
Whether the BNC connector or video cable is in good contact;
If you use a manual aperture lens, you need to check whether the aperture is open. If you use an automatic aperture lens, you need to adjust the LEVEL potentiometer to make the aperture at the appropriate position.