1, ball valve. The valve core is a sphere with holes. When one side of the perforation rotates to be parallel to the valve body, that is, the left and right sides are transparent, water will flow out. When the perforated side rotates to be perpendicular to the valve body, that is, close to the valve wall, no water will flow out.
2. Gate valve. The principle of valve core is the same as that of dam gate. The lower the water flowing from the gate core, the smaller the water will be until it is closed.
Extended data:
The internal structure of traditional water meter can be divided into three parts: shell, sleeve and inner core from outside to inside. The shell is made of pig iron, and the water passes through the lower annular space of the shell after coming out of the water inlet, which is called the "lower annular chamber" here. Above this annular space, there is an "upper ring chamber" communicating with the water outlet. There is a filter screen with small holes at the bottom of the sleeve to filter out impurities in water.
There are upper and lower rows of circular holes on the side of the sleeve, and the positions of the holes are opposite to the upper and lower annular cavities of the shell. Obviously, the lower row is the water inlet hole and the upper row is the water outlet hole. It is particularly noteworthy that these two rows of holes are made obliquely along the tangent direction of the circle. Note that the upper and lower rows of holes are in opposite directions.
The tangential inflow of water from the lower drainage hole is bound to form a rotating water flow, which is very important for the work of the water meter. The inner core is divided into upper, middle and lower layers. From the glass window, you can see the upper layer, only the pointer and dial. In fact, the most important thing is the lower floor, where there is a plastic wheel with many plastic blades on the edge, called "impeller".
References:
Baidu encyclopedia-water meter
Baidu encyclopedia-gate valve
Baidu encyclopedia-ball valve