Dosing Pump Accuracy: What Plus Or Minus One Percent Really Means

Every dosing pump datasheet quotes accuracy, but the number only means something against a test method. Here is how to read the claim, and how to keep it.

Repeatability Versus Linearity

Repeatability is how close successive strokes land; linearity is how the pump tracks across its turndown range. A pump can repeat within one percent at full stroke and still drift badly at ten percent stroke. Ask for the accuracy across the range you will actually run.

Where Accuracy Is Lost

Not usually in the pump. It is lost in the installation: soft suction hoses that expand, missing pulsation dampers, collapsed foot valves, and gas build-up in hypochlorite service. The pump head does not cause these, but it pays for them.

How We Calibrate

Every AF-D pump is calibrated across its stroke range before shipment and the measured points ship with the pump. At commissioning, run a five-minute drawdown test against a measuring column; it should match the certificate within the stated band.

Keep It

Re-check calibration quarterly, flush the head on the schedule in the manual, and keep the day tank concentration consistent. Accuracy is a system property, maintained, not bought.