The “starting flow rate” (designated as Q₁ in metrological standards) is defined as the minimum water flow rate at which a mechanical water meter can initiate rotation of its internal measuring mechanism (e.g., impeller) and perform valid volume measurement.
Key technical requirements are specified as follows:
- At the starting flow rate Q₁, the meter’s measurement error must comply with the limits specified by its accuracy class (e.g., ±5% for Class 1 meters and ±3% for Class 2 meters per ISO 4064-1:2014).
- The meter shall demonstrate sensitive startup without jamming or hysteresis, ensuring reliable measurement of ultra-low flow conditions (such as dripping water) that are typical in domestic or light commercial applications.
- The starting flow rate value is determined through standardized testing, which requires the meter to register cumulative volume consistently when water flows at Q₁, with no significant delay or failure to initiate measurement.
These requirements are critical to preventing unrecorded water consumption and ensuring the meter’s compliance with legal metrology regulations.
Post time: Nov-18-2025