A Study On On-line Leak Detection Technology Of Valve

In the actual application of the valve, there are no measures to prevent leakage between the packing and the valve body, so the leakage at the stuffing box often occurs. In order to meet the actual demand, this paper studied the leakage occurred at the valve packing and created two kinds of on-line monitoring device for valve leakage through study on the valve leakage outside the state with two experimental methods. A valve leakage on-line monitoring system was designed and developed, at the same time, the cloud server collects real-time data of the valve leakage which will then be received by PC software and APP to achieve real-time monitoring through distant alarm. The CFD software was used to simulate the bubble formation and the shape change process, which was consistent with the result obtained by high speed camera. The main conclusions of this research are as follows:(1) For bubble measurement, the breakthrough pressure of the hydrophobic membrane is about 1800Pa. The relationship between the pore size of the leakage port and the diameter of the single bubble is determined. When the pore size of the leakage port is 0.9mm, the volume of the single bubble is 0.02mL, the diameter of the single bubble is 3.3677mm. When the pore size of the leakage port is 0.5mm, the volume of the single bubble is 0.015mL, the diameter of the single bubble is 3.05mm.(2) For the study of bubble dynamics, the changing rules about bubble shape during the process of single bubble rising is as follows:while the formation moment of bubble its shape is round ball, it will gradually into the oval when floatation, and then become a crescent shape, finally it will be a flat hat shape, under the pressure and free surface tension the bubble will be elongated in the horizontal direction until the bubble break through the bondage of free surface, finally it will be broken.(3) For the monitoring system, it consists of remote collection device, network transmission and remote terminal units. Employing the embedded development system, the real-time valve leakage monitoring system is designed. Its hardware consists of a controller with ATmega48 as its core and the peripheral circuits, including base circuit, drive circuit, sound light alarm circuit and protection circuit. At the same time, the software has been developed which with visible interface can monitor the testing process in real time and display the results, and can manipulate data at any moment, surveillance data are visualized.