Learn the meaning of Q1, Q2, Q3, Q4 in water meters. Understand flow rate classes defined by ISO 4064 / OIML R49 and their importance for accurate billing and sustainable water management.
When choosing or comparing water meters, technical sheets often list Q1, Q2, Q3, Q4. These represent the metrological performance levels defined in international standards (ISO 4064 / OIML R49).
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Q1 (Minimum flow rate): The lowest flow where the meter can still measure accurately.
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Q2 (Transitional flow rate): The threshold between minimum and nominal ranges.
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Q3 (Permanent flow rate): The nominal operating flow used for standard conditions.
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Q4 (Overload flow rate): The maximum flow the meter can handle without damage.
These parameters ensure accuracy, durability, and compliance. For water utilities, understanding Q1–Q4 is essential to select the right meter for residential, commercial, or industrial applications.
With the global push toward smart water solutions, knowing these basics helps utilities and consumers alike make informed decisions.
Post time: Aug-26-2025
