Smart water meter in the maximum flow is, the pressure loss should not exceed 0.1MPa. Therefore, in the water meter design calculation, we must first meet this requirement. At the same time, do not affect the water meter of the initial genre, the smallest fleas, etc. under the premise of the smaller the better the pressure loss.

Water meter in the normal use of water through the parts of the cross-section, it will produce eddy current. Therefore, the water flow in the water meter is almost always in turbulent state. Because the turbulence movement of water quality is complicated, although many people have made a lot of research at home and abroad in recent decades, the inherent law of turbulence is still not fully understood and grasped. So far, the turbulence state of the local pressure loss calculation, mainly by trying to study the empirical formula.

If the water supply system from the point of view, the water meter itself is only a local pressure caused by the "accessories." Therefore, the local pressure loss and the pipeline along the same pressure drop can be used to measure the multiple of the flow head to measure. If the filter net shape for the tube, such as its cross-sectional area is equal to or greater than the nominal diameter of 1.5 times the area.

The main cause of the pressure loss of the water meter is the impeller case and case. But the nominal diameter of the case and the length of the basic shape, easy to make changes, so the case of partial pressure can be approximated as a constant. As for the water filter and impeller and other moving parts of the pressure loss, accounting for the proportion of the whole machine pressure loss is small, even if the pressure loss of some changes in the impact of the whole machine pressure is not large, so negligible.

The local pressure loss of the impeller disk is the main factor that causes the pressure loss of the remote water meter, and the cross-sectional area of the inlet and outlet of the impeller box is the key factor to make the impeller box cause the local pressure loss. Therefore, as long as the calculation of the impeller box into the water hole total area F will be able to grasp the size of the water gauge pressure loss, so as to ensure that the requirements of national standards.