In recent years, some leak detection equipments have appeared at home and abroad, which have played an important role in the detection of water leakage in the main water supply pipeline. For example, the leak detection system produced by Kay Company of the United States is powerful, but the price is high, and it is large in units and households. Promotional applications are greatly limited. The F series leaking and leaking detector equipment produced by a company in China, because there is no networking, the equipment does not set a variety of alarm functions such as telephone dialing, SMS sending, mail sending, etc., which greatly restricts the application and application scope of the equipment. . Therefore, it is necessary to study a device and system that is low in power consumption and low in price and can be accepted by most units and individuals, and is particularly suitable for water leakage detection near the water supply terminal, so as to reduce the accidental damage of the water supply terminal and fail to obtain timely maintenance. The resulting massive waste of water resources has occurred. The system networking consists of a main monitoring system module and multiple on-site monitoring node modules to form a water leakage monitoring network. The main monitoring system module completes the receiving and processing of information, and realizes the alarm in the form of telephone dialing, sending short messages, sound and light, etc., so that the terminal that leaks water is timely repaired in the shortest time. The on-site monitoring node realizes the accurate detection and identification of the water leakage position of the water supply terminal. If there is a phenomenon of terminal leakage, the data transmission and reception module sends an alarm message to the main monitoring system module, and then sends an alarm message to the maintenance personnel through the main monitoring system. The system networking and overall design are shown in Figure 1. The monitoring node mainly comprises embedded industrial control template, ultrasonic flow detection module, pyroelectric human body detection module, wireless transceiver circuit, sound and light alarm circuit, solenoid valve control and other circuits. The hardware composition is shown in Figure 2. 2.1 Embedded Industrial Control Template M2080 Carton Closing Staples,Packaging Industrial Staple,Copper Coated Staple,Moistureproof Packing Nails Zhejiang Best Nail Industrial Co., Ltd. , https://www.beststaple.com
The M2080-U20 is a cost-effective MiniARM industrial control module that uses the LPC2220 industrial-grade embedded microcontroller to integrate ARM minimum system, Ethernet/CAN/USB controller, and Flash on Board into a compact module. On top, pre-installed μC/OS-II real-time operating system, underlying basic driver library, middleware software function library (FAT file management system, Ethernet, CAN-bus, USB DevICe/Host/OTG, CF/SD/MMC Card, ZLG500, GPRS/CDMA and other modules), providing bus protection design, so that the module has good EMC performance and stability.
2.2 Ultrasonic flow detection module
2.2.1 Principle of ultrasonic flow monitoring Ultrasonic flow monitoring uses a non-intrusive or clamped ultrasonic flow sensor, installed on existing pipelines, or as a pipe section. The basic structure is shown in Figure 3. Ultrasonic waves enter the pipe and the liquid through a wedge made of plastic or metal material. According to Snell's law, the originating sound wave appears transverse and longitudinal waves at the interface of the steel pipe, and the transverse wave enters the liquid, and the longitudinal wave is totally reflected off. After the ultrasonic wave enters the liquid, it becomes a longitudinal wave. After passing through the liquid, it is received by the ultrasonic transducer 2 through the obliquely opposite tube wall and the acoustic wedge. The acoustic signal from the ultrasonic transducer 1 to the ultrasonic transducer 2 is forward; the reverse is reverse.
The time difference method is to measure the flow rate by measuring the time difference between the forward propagation and the reverse propagation of the ultrasonic pulse in the liquid. The specific calculation formula and measurement method are described in the literature.
Figure 3 Principle of ultrasonic flow detection 