A dosing pump’s displayed flow rate and its actual delivered flow rate are only guaranteed to match at the exact moment it was last calibrated. Backpressure changes as downstream valves are adjusted or lines start to foul. Chemical viscosity shifts with temperature and concentration. Neither of these announces itself, the display keeps showing the same number regardless of what the pump is actually delivering, and most wastewater treatment plants have no routine in place to catch the resulting inaccuracy before it compounds across thousands of dosing events.
Why This Goes Unnoticed
Calibration inaccuracy doesn’t produce an alarm or a visible symptom at the pump. It shows up as a chemical consumption figure that doesn’t quite match expected dosing, or a process outcome, turbidity, residual chlorine, pH, that shifts slightly out of the expected range without an obvious cause. Because the pump itself gives no indication anything has changed, the usual trigger for investigating is a process failure rather than a scheduled check.
Manual Calibration: Entering a Known Value
The Atlanta’s manual calibration lets the operator enter a known flow rate directly, in millilitres per minute or fluid ounces per minute, based on a measurement taken independently, a graduated cylinder and a stopwatch, for example. This is a fast way to correct the pump’s displayed value once an actual output has already been measured by some other method.
Automatic Calibration: The Pump Measures Itself
Automatic calibration takes this a step further by having the pump verify its own output rather than relying on an external measurement. The operator sets a dosing speed, and the control unit automatically calculates a calibration time based on that speed, adjustable if needed, then runs the pump for that duration into a measuring vessel. At the end of the run, the display shows the dosed quantity it calculated, and if that figure doesn’t match what was physically measured in the vessel, the operator adjusts the displayed value to the real one directly on the device. That corrected value is what the pump uses in all subsequent flow calculations, and a successful calibration is confirmed by the display backlight turning green.
The Rule That Ties It Together
The manufacturer’s documented guidance is direct: recalibrate every time the mechanical stroke length is adjusted by hand. A manual adjustment changes the pump’s physical output, but the electronic dosing figures on the display don’t automatically know that, without recalibration, the two fall out of alignment immediately, and every dosing calculation downstream inherits the inaccuracy from that point on.
Turning This Into a Routine, Not a One-Off
Calibration on most pumps is treated as a commissioning step, done once and left alone. Given how easily backpressure and viscosity conditions change in a wastewater plant, it works better as a scheduled maintenance item: recalibrate whenever the stroke length is adjusted, whenever the chemical or its concentration changes, whenever discharge-side plumbing is modified, and on a routine interval regardless, monthly or quarterly, depending on how much the process conditions at that dosing point typically move. A password lock on the configuration menu then protects the calibrated value from being changed inadvertently between scheduled checks.
Where This Fits
This matters most at any dosing point where the cost of being wrong is high, disinfection, pH correction, or any chemical whose accuracy is directly tied to a discharge consent limit.
Autoflo Technology is the authorised distributor of the Injecta Atlanta series in Malaysia. For help building a calibration schedule for your dosing points, contact us at info@autoflotechnology.com.