Q1 Minimum flow rate
Q2 Transitional flow rate
Q3 Permanent flow rate (working flow)
Q4 Overload flow rate
Make sure that the maximum flow that will pass through the meter never exceeds Q3.
Most water meters have a minimum flow (Q1), below which they cannot provide an accurate reading.
If you choose a large meter, you may lose accuracy at the lower end of the flow range.
Meters that continually operated on the overload flow range (Q4) have a shorter life span and less accuracy.
Size your meter appropriately for the flow you intend to measure.
Turndown ratio R
The metrological working range is defined by the Ratio (This value is the relation between Working flow / Minimum flow).
The higher the “R” Ratio, the greater sensitivity the meter has for measuring low flow rates.
The standard values of the R ratios in water meter are the following*:
- R40, R50, R63, R80, R100, R125, R160, R 200, R250, R315, R400, R500, R630, R800 , R1000.
(*This list can be extended in some serials. Be aware that this this nomenclature is replacing the old metrological classes A, B, and C)
And remember that a meter will only be accurate if the environmental conditions meet all the manufacturer’s requirements of flow profile, installation, temperature, flow range, vibration etc.
Lanry Instruments Ultrasonic water meter Ultrawater(DN50-DN300) serials Turndown ratio R is 500; SC7 serials (DN15-40) Turndown ratio R is 250; SC7 serials (DN50-600) Turndown ratio R is 400.
Post time: Oct-14-2021