Water meter is an instrument for measuring water flow, mostly the cumulative flow of water. Generally divided into two types: volumetric water meter and speed water meter. It originated in Britain and has a history of nearly 200 years. When choosing the specifications of water meters, we should first estimate the size and range of the flow used under normal circumstances, and then choose the most common flow as the first choice.
school term
Minimum flow (Q 1): The indicated value of the water meter is required to meet the minimum flow in maximum permissible error.
Boundary flow (Q2): the flow that occurs between the ordinary flow Q3 and the minimum flow Q 1. The flow range is divided into "high area" and "low area" with specific maximum permissible error.
Ordinary flow (Q3): the maximum flow under rated conditions. At this flow rate, the water meter should work normally and meet the requirements of maximum permissible error.
Overload flow (Q4): The maximum flow that requires the water meter to meet the requirements of maximum permissible error in a short time, and then can still maintain metering characteristics under rated working conditions.
Pressure loss (Δ P): At a given flow rate, there is a water meter in the pipeline, resulting in head loss.