Chemical dosing pump sizing
Size a metering pump from water flow, target dose and stock solution strength, with output in L/h and a duty-point check against the 20–80% stroke rule.
Results
| Required pump output | 2 L/h |
|---|---|
| Solution consumption per day (24 h) | 48 L |
| Duty point on selected pump | 40% of capacity |
A duty point of 40% sits inside the 20–80% band, giving good repeatability with room to trim the dose either way.
Catalogue pumps for this duty
Pumps that deliver 2 L/h inside the 20–80% band where they dose repeatably, smallest first: choose one. Each lists its own back-pressure rating; check it against your line pressure.
Dosing pump option
DOSAMS200Seko Kompact AMS200 solenoid dosing pump, 5 L/h, 10 bar max.
8–12 weeksIndent
Dosing pump option
SEKOAKS603Seko Tekna AKS603 solenoid dosing pump, 8 L/h, 12 bar max.
8–12 weeksIndent
Dosing pump option
DOSTPG603Seko Tekna TPG603 solenoid dosing pump, 8 L/h, 12 bar max.
8–12 weeksIndent
Dosing pump option
DOSTPR603Seko Tekna TPR603 solenoid dosing pump, 8 L/h, 12 bar max.
8–12 weeksIndentChemical tank
CHEMTANK80LChemical dosing tank, 80 L, square
Ex-stock (0–3 days)Low stock
Chemical tank
CHEMTANK100LChemical dosing tank, 100 L
8–12 weeksIndent
Formula used
q = Q × D ÷ C
C (g/L) = strength (% w/v) × 10
duty (%) = q ÷ q_max × 100
- q
- required pump output, L/h
- Q
- water flow being dosed, m³/h
- D
- target dose, mg/L (= g/m³)
- C
- active concentration of stock solution, g/L
- q_max
- selected pump's maximum output, L/h
Percentage strength is taken as weight-per-volume (% w/v). For chemicals supplied by weight (% w/w), multiply by the solution density first. The 20–80% duty band is the usual guidance for a solenoid metering pump set by stroke length; a pump that trims its output by stroke frequency, or one running under an external 4–20 mA or pulse signal, has its own turndown, so check the model's own stated minimum before sizing to this band.
The background
- Sizing a dosing pump: the arithmetic and the 20–80% ruleDosing pump selection is one formula and one discipline: calculate the true duty point, then make sure it lands in the middle of the pump's range, against the real pressure.
- Metering pump types: solenoid, motor-driven diaphragm and peristalticThree technologies for pushing small, precise chemical flows against pressure, each with a duty range where it is the obvious choice and edges where it is the wrong one.
- Injection points, back-pressure valves and the syphoning faultMost dosing problems start at the two ends of the chemical's journey rather than in the pump. How to build an injection point that doses what the pump meters and nothing more.
Equipment for this duty
Send the water analysis and duty point, and the branch confirms exact selections, pricing and lead times, usually within one working day.
Request a quoteResults are indicative engineering estimates based on standard formulas and typical assumptions. They are not a design service; confirm any design against a full water analysis and the relevant manufacturer’s data.