The Digital Video Recorder, also called the DVR/ DVR Security System/ DVR monitor/Digital Video Recorder H.264/ DVR CCTV, is the video storage device of the AHD Four in One Camera(the video capture device). The Digital Video Recorder records the video with the hard disk that we put in it, and it is a computer system for image storage and processing, which has the functions of long-term image recording, voice recording, remote monitoring and control of images/voices.
Recording function: The video resolution is the core of the digital host because the video effect is more important to the Forensics than the on-site video effect. Most Digital Video Recorder can achieve on-site recording at 25 frames per second.
Password authorization function: in order to reduce the failure rate of the system and illegal entry, a password need to be set for procedures such as stopping video recording, arming and disarming the system and entering programming, so that unauthorized people cannot operate these procedures. The Password authorization is usually set as the multi-level password authorizations.
Work Schedule function: The user can program the working time for one certain period of time of one certain camera, which is also the unique function of the host of the Digital Video Recorder. The user can pre-schedule all the changes of holidays and working schedules into the program, which can realize the unattended in some extence.
All in all, the Digital Video Recorder represents the developing direction of CCTV monitoring system and it has been the first choice on the CCTV monitoring system market.
Digital Video Recorder, DVR Security System, DVR Monitor, DVR, Digital Video Recorder H.264, DVR CCTV SHENZHEN SANAN TECHNOLOGY CO.,LTD , https://www.sanan-cctv.com
The ball valve is mainly used in the pipeline to cut, distribute and change the flow direction of the medium. Ball valve is a new type of valve widely used in recent years, which has the following advantages:
1. The fluid resistance is small, and its resistance coefficient is equal to the pipe length of the same length.
2. The structure is simple, small in size and light in weight.
3. It is compact and reliable. At present, the sealing surface material of the ball valve is widely used in plastic and has good sealing performance. It has also been widely used in vacuum systems.
4. The operation is convenient, the opening and closing is rapid, and the rotation is 90° from full opening to full closing, which is convenient for long-distance control.
5. The maintenance is convenient, the ball valve has a simple structure, and the sealing ring is generally movable, and the disassembly and replacement are relatively convenient.
6. When fully open or fully closed, the sealing surface of the ball and the valve seat is isolated from the medium, and the medium does not cause erosion of the sealing surface of the valve.
7. Wide range of applications, from small to a few millimeters, up to a few meters, from high vacuum to high pressure can be applied.
Ball valves have been widely used in petroleum, chemical, power generation, paper, atomic energy, aviation, rocket and other departments, as well as people's daily lives.
The ball valve can be divided according to the structure:
1. The ball of the floating ball valve is floating. Under the action of the medium pressure, the ball can generate a certain displacement and press on the sealing surface at the outlet end to ensure the sealing of the outlet end.
The floating ball valve has a simple structure and good sealing performance, but the load of the ball subjected to the working medium is all transmitted to the outlet sealing ring, so it is necessary to consider whether the sealing ring material can withstand the working load of the spherical medium. This structure is widely used in medium and low pressure ball valves.
Second, the ball of the fixed ball valve is fixed, and does not move after being pressed. The fixed ball valve has a floating valve seat. After the medium pressure, the valve seat moves, so that the sealing ring is pressed against the ball to ensure the seal. Usually mounted on the upper and lower shafts of the ball, the operating torque is small, suitable for high pressure and large diameter valves.
In order to reduce the operating torque of the ball valve and increase the reliability of the seal, oil seal ball valves have appeared in recent years, and the special lubricating oil is injected between the sealing faces to form an oil film, which enhances the sealing performance and reduces the operating torque. It is more suitable for high pressure and large diameter ball valves.
Third, the ball of the elastic ball valve ball valve is elastic. Both the ball and the seat ring are made of metal material, and the sealing pressure is very large. The pressure of the medium itself cannot meet the sealing requirements, and an external force must be applied. This valve is suitable for high temperature and high pressure media.
The elastic sphere is made by opening an elastic groove at the lower end of the inner wall of the sphere to obtain elasticity. When the passage is closed, the wedge of the valve stem is used to open the ball and press against the seat to seal. Before the ball is rotated, the wedge head is loosened, and the ball is restored to its original shape, so that a small gap occurs between the ball and the valve seat, which can reduce the friction and operating torque of the sealing surface.
Ball valves can be divided into straight-through, three-way and right-angle types according to their channel positions. The latter two ball valves are used to distribute media and change the flow of the media: http://
The Digital Video Recorder is far superior to the analog monitoring equipment in terms of the image processing, image storage, retrieval, backup, network transmission, and remote control because of the adoption of the digital recording technology.
By the way, there are many BNC video interfaces on the back of the Digital Video Recorder, each interface can be connected to an analog suveillance camera. Just plug the interface, then it works, very convenient!
Generally speaking, the Digital Video Recorder can be divided into the hard disk video recorder, the PC type hard disk video recorder and the embedded hard disk video recorder, etc. Among them, the embedded hard disk video recorder does well in the stablity, the reliability, and the easy use, and the embedded hard disk video recorder will gradually invade the market of the PC type hard disk video recorder.
Besides, The main functions of the Digital Video Recorder include: monitoring function, recording function, playback function, alarm function, control function, network function, password authorization function and work schedule function.
Monitoring function: The monitoring function is one of the most important functions of the Digital Video Recorder. Whether it can monitor the on-site camera video clearly is a core issue of the surveillance system. Most Digital Video Recorders can achieve clear on-site surveillance.
Alarm function: The alarm function mainly includes the input alarm of the detector and the alarm of the image and video detection. Once received the alarm signal, the system will automatically start recording, and turn on the corresponding spotlight, siren and network output signal via the alarm output function. The image motion detection is the main alarm function of the Digital Video Recorder.
Control function: The control function refers to the omnidirectional control of the PTZ and lens via the host, which is generally finished by the dedicated decoder and the keyboard.
Network function: The user can do various operations to the host such as the monitoring, recording and control after the simple identification on the LAN or WAN, which is similar to the local opertaion.
Stainless steel flange ball valve features and classification
The ball valve and the plug valve are the same type of valve, only the closing member of which is a ball, and the ball rotates around the center line of the valve body to open and close a valve.