How to understand Q4, Q3, Q2, and Q1 of water meters?

1. Definition of Q4
   • Q4 is the reference flow rate. It is the maximum flow rate at which a water meter can continuously operate without any damage or significant deviation in measurement accuracy. For example, in a residential water supply system, if a water meter has a Q4 value of 2.5 m³/h, it means that under normal operating conditions, the water meter can handle a maximum continuous flow rate of 2.5 cubic meters per hour without performance degradation.
2. Explanation of Q3
   • Q3 is the rated flow rate. This is the flow rate at which the water meter operates within its specified accuracy range under normal working conditions. It is an important parameter for determining the appropriate size of a water meter for a particular application. In a commercial building with a certain water consumption pattern, the water meter’s Q3 value needs to be carefully selected to ensure accurate measurement. If the actual water flow in the building usually fluctuates around 1.5 m³/h, a water meter with a suitable Q3 value close to this flow rate should be chosen.
3. Understanding of Q2
   • Q2 is the transition flow rate. It marks the boundary between the lower and higher accuracy regions of the water meter. Below Q2, the accuracy of the water meter may decrease significantly. For instance, in a water distribution network with low – flow periods at night, when the flow rate drops below the Q2 value of the installed water meter, the measurement error may increase, which needs to be considered in the design and operation of the water metering system.
4. Meaning of Q1
   • Q1 is the minimum flow rate. It is the lowest flow rate that the water meter can accurately measure. In a small – scale irrigation system where the water flow may be very low during certain stages, a water meter with a low Q1 value is required to accurately record the water consumption. If the Q1 value of the water meter is too high, it may not be able to detect and measure the small amounts of water flowing through the system accurately.

In summary, Q4, Q3, Q2, and Q1 are crucial parameters for understanding the performance and application scope of water meters, which play an important role in the proper selection and effective operation of water meters in various water – using scenarios.