Dosing Pump Flow Calculator: From Target ppm to L/h
Calculate the required dosing pump flow from target dose, main line flow, chemical concentration and density. The formula and an example table are on the page and readable with JavaScript turned off.
Required Dosing Pump Flow
Enter four values; pump flow, capacity with margin and daily consumption are calculated instantly.
Result
| Suggested pump capacity (+20 %) | – |
|---|---|
| Suggested pump capacity (+30 %) | – |
| Daily consumption (24 h continuous) | – |
The 20–30 % margin is typical engineering practice, not a standard. Results are for preliminary sizing.
The Equation Behind the Calculation
Derivation. Since 1 ppm = 1 mg/L and 1 m³ = 1000 L, the active mass needed per hour in the main line is ppm × Qmain grams. One litre of chemical contains 1000 × ρ × C/100 = 10 × C × ρ grams of active substance. Dividing the required active mass by the active substance per litre gives the pump flow in L/h. The dosed volume is very small compared with the main flow, so the increase in main line flow is neglected.
Margin. In typical engineering practice the capacity of the pump to be selected is left 20–30 % above the calculated flow; the calculator shows both values separately. The discharge pressure of the pump, the viscosity of the chemical and material compatibility are evaluated separately.
Worked Examples
The result of the formula in five different cases; readable without JavaScript.
| Target dose (ppm) | Main flow (m³/h) | Concentration (%) | Density (g/cm³) | Pump flow (L/h) | +20 % (L/h) | +30 % (L/h) |
|---|---|---|---|---|---|---|
| 5 | 50 | 30 | 1.15 | 0.72464 | 0.86957 | 0.94203 |
| 10 | 100 | 100 | 1.00 | 1 | 1.2 | 1.3 |
| 2 | 200 | 10 | 1.05 | 3.8095 | 4.5714 | 4.9524 |
| 20 | 25 | 50 | 1.30 | 0.76923 | 0.92308 | 1 |
| 1 | 500 | 15 | 1.10 | 3.0303 | 3.6364 | 3.9394 |
Values are for ppm of active substance and are for preliminary sizing.
A Dosing Pump for the Calculated Flow
If you tell us the calculated flow, the pressure at the injection point and the properties of the chemical, we will select a suitable dosing pump together. For dosing pump selection and maintenance: metering pumps · pumps · dosing pump maintenance. Other tools: conductivity unit converter · PT100 resistance table · all tools.
Dosing Pump Flow Calculation: Frequently Asked Questions
Formula, derivation, margin and input definitions.
How is dosing pump flow calculated?
Pump flow (L/h) = target dose (ppm) × main line flow (m³/h) ÷ (10 × chemical concentration (%) × chemical density (g/cm³)). Here ppm means mg/L of active substance in the main line. Example: 5 ppm, 50 m³/h, 30 % concentration and 1.15 g/cm³ density give a pump flow of about 0.72 L/h.
Where does the number 10 in the formula come from?
The active mass needed per hour in the main line is ppm × Q grams (since 1 m³ = 1000 L and 1 ppm = 1 mg/L). One litre of chemical contains 1000 × density × (% ÷ 100) = 10 × % × density grams of active substance. Dividing the two gives the formula; the 10 comes from the unit conversion.
Why is a margin added to the calculated flow?
In typical engineering practice the selected pump capacity is left 20–30 % above the calculated flow, which leaves room for flow fluctuations, concentration differences, check valve and suction losses and a later increase in dose. This is common practice, not a standard; evaluate the pump selection together with pressure, chemical viscosity and dosing accuracy requirements.
Is ppm entered for the product or the active substance?
The calculator treats ppm as active substance and uses the chemical concentration (%) as the share of active substance in the product. If your target is ppm of the product itself, enter 100 % concentration and the density of the product.
What should I check in the calculation?
The pressure at the injection point must not exceed the discharge pressure limit of the pump, and the pump flow must remain within the pump's adjustment range. If the main flow varies, dosing is proportioned by a signal (flow meter or conductivity/pH controller). The results are for preliminary sizing; the final selection is based on chemical material compatibility and the safety data sheet.
Let Us Select Your Dosing Pump Together
Share the flow you calculated, the injection point pressure and the chemical information, and we will define the pump and dosing configuration together.
Planning a project? Send us your flow rate, feed water source and target water quality to [email protected] — our engineers will reply with a technical proposal.