Reagent
Fraction, e.g. 0.5 = 50 %
Awaiting Valid Duty Parameters
Adjust the parameters on the left to compute live hydraulic values, ranges, and sizing verdicts.
Dosing pump under- or over-dosing?
We supply and service diaphragm dosing pumps with correct sizing, pulsation damping and calibration — the right dose, every shift.
Dosing pump sizing explained
The dosing formula
Required rate (L/h) = dose (mg/L) × process flow (m³/h) ÷ (1000 × purity). Purity is the reagent fraction — 0.5 for a 50 % solution. For 25 mg/L of alum at 50 m³/h with a 50 % solution: 25 × 50 ÷ (1000 × 0.5) = 2.5 L/h. The presets fill typical values; every plant should use its jar-test or design dose.
Add 10–20 % turndown: diaphragm pumps are chosen so the operating point sits in the middle of their stroke range, not at the edge.
Choosing the pump type
Diaphragm dosing pumps suit most ETP reagents — accurate, leak-tight, and able to handle hypochlorite, alum and polymer with the right wetted parts. Peristaltic pumps suit polymer and viscous dosing. Materials follow the compatibility matrix: hypochlorite needs PTFE/EPDM wet-end parts; NaOH is fine with PP and EPDM.
Backpressure matters: a dosing pump needs stable discharge pressure to dose accurately — pulsation dampers and calibration columns are standard additions on ETP skids.
From rate to pump
Match the calculated L/h to a pump capacity about 1.5× the required rate so the pump runs mid-stroke at 50–70 % stroke length, which gives the best accuracy and diaphragm life. Teflow supplies and services diaphragm dosing pumps for ETP, RO and process plants across Gujarat — call +91 98251 62709 for a sizing and quote.
Technical & Operational FAQs
Q1.How do I calculate dosing pump LPH?
LPH = dose (mg/L) × process flow (m³/h) ÷ (1000 × reagent purity). For 25 mg/L at 50 m³/h with a 50 % alum solution: 25 × 50 ÷ 500 = 2.5 L/h. Select a pump rated about 1.5× the required rate for mid-stroke operation.
Q2.What is purity in the dosing formula?
Purity is the active fraction of the reagent — 0.5 for 50 % NaOH or 50 % alum, 0.12 for 12 % hypochlorite. More dilute reagents mean more litres to pump for the same dose.
Q3.Which dosing pump for sodium hypochlorite?
A diaphragm pump with PTFE or EPDM wetted parts — hypochlorite degrades FKM and attacks metals. Include pulsation damping and a calibration column, and flush the head if the pump sits idle.
Q4.What size dosing pump do I need for my ETP?
Compute the L/h for each reagent from the design dose and flow, add 10–20 % turndown, then pick the pump whose mid-stroke capacity matches. A 5–10 L/h pump covers most small ETPs; larger plants step up per stream.
Q5.Why does my dosing pump over-dose?
Common causes: stroke set too high for the actual flow, wrong purity entered in sizing, backpressure changes, or air in the head. Recalculate the rate with real dose and purity, calibrate against a column, and check the discharge for pulsation.
Related Engineering Tools
Need a custom hydraulic audit or specific duty curve verification? Call +91 98251 62709 or Request a Detailed Engineering Quote.