Why Dosing Pump Selection Matters
A dosing pump (also called a metering pump) delivers precise, repeatable volumes of liquid chemicals into a water treatment process. Getting the selection wrong results in chemical over-dosing (wastage and potential harm), under-dosing (poor treatment quality), or pump failure from chemical incompatibility. Taking time to specify correctly pays off in plant performance and operating cost.
Types of Dosing Pumps
Solenoid-Operated Diaphragm Pumps
A solenoid coil drives the diaphragm back and forth at a fixed frequency. The flow rate is adjusted by varying the stroke length or stroke frequency. These pumps are simple, compact, and cost-effective for smaller flows (typically up to 100 L/hr). Toshcon Jesco magnetic drive pumps fall in this category.
Motor-Driven Diaphragm Pumps (SEKO)
A motor and eccentric cam drives the diaphragm, allowing very accurate and consistent dosing at higher flow rates. SEKO dosing pumps use this mechanism and are suited to industrial-scale water treatment plants where accuracy and reliability are critical.
Peristaltic Pumps
A rotor squeezes a flexible hose to push fluid forward. Good for slurries and highly viscous fluids but less accurate than diaphragm types for precise chemical dosing.
Key Specifications to Define
| Specification | How to determine it |
|---|---|
| Flow rate (L/hr) | Dose concentration × process flow rate |
| Discharge pressure (bar) | System pressure + pipe losses + back-pressure |
| Chemical compatibility | Check wetted parts (PVDF, SS316, PP) against chemical SDS |
| Dosing accuracy | ±1–2% for most water treatment; ±0.5% for pharma |
| Control signal | Manual, 4–20 mA, pulse, or SCADA-controlled |
| Viscosity of chemical | High viscosity needs special valve or peristaltic design |
Common Chemicals Dosed in Water Treatment
- Sodium hypochlorite (NaOCl) — disinfection
- Alum (aluminium sulphate) — coagulation
- Caustic soda / sulphuric acid — pH correction
- Antiscalant — RO membrane protection
- Ferric chloride — coagulation in ETP
- Polymer (polyelectrolyte) — sludge flocculation
Toshcon & SEKO Dosing Pumps from QuaSys
QuaSys Inc. is an authorized dealer for Toshcon Jesco and SEKO dosing pumps in India. Our team will help match the right model to your chemical, flow rate, and control requirements. Call +91 11 29531287 or get in touch.
