The shell is made of cast iron. After water comes out from the water inlet, it passes through the lower annular space of the shell, which is called "lower ring chamber". On the top of the annular space, there is a "upper ring chamber" connected with the water outlet. The bottom of the sleeve has a filter screen with small holes to filter out the impurities in the water. There are two rows of round holes on the side of the sleeve. The position of the holes is just opposite to the upper and lower ring chambers of the shell. The inner core is divided into upper, middle and lower layers. The upper layer can be seen from the glass window, with only the pointer and dial. There is a plastic wheel in the lower layer. There are many plastic blades on the edge of the wheel, which is called "impeller".
The position of the impeller is just in the rotary flow formed by the hole in the lower layer of the casing pipe. The water flow impacts the blade around the wheel, and generates torque to make the impeller rotate. The bigger the faucet is, the faster the flow is, and the faster the impeller will turn.
Thus, the water meter shaft needs to be corrosion-resistant, non rusting, water pressure resistant, relatively high hardness and no deformation. Tungsten steel water meter shaft has these advantages and perfectly replaced the steel shaft.