The lowest approved flow passing through the meter.
The boundary flow is the flow between low flows and higher measurement errors and higher flows and lower measurement errors.
The constant flow for which the meter is approved. When selecting a meter choose the meter whose Q 3 flow is closest to the probable flow is selected.
The largest short-term flow that the meter manages satisfactorily without taking any damage, is normally short-lived as 1 hour per day or a maximum of 200 hours per year.
An older way of measuring water flow according to EEG
| Comparison of Q3 and Qn | ||||||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Permanent flow | Q3 | 2,5 | 4 | 10 | 16 | 25 | 40 | 63 | 100 | 160 | 250 | m3/h |
| Nominal flow | Qn | 1,5 | 2,5 | 6 | 10 | 15 | 25 | 40 | 60 | 100 | 150 | m3/h |
A compilation of some advantages and disadvantages of having parallel connected meters compared to a larger one.
| Benefits of parallel connected meters | |
| - Replacement or servicing of meters does not cause any interruption in the water supply to the building. | |
| - The fixed annual cost is in many cases lower with more and smaller meters than a larger one. | |
| - With varying consumption that parts of the premises are not used, it is easier to reduce the subscription. | |
| Disadvantages with parallel connected meters | |
| - Takes up more space. | |
| - More pipes and valves provide a higher installation cost. | |