Chemical Metering & Dosing Pumps
When your spec calls for repeatable accuracy and tight process control, metering pumps deliver. We size solenoid & motor-driven diaphragm, API 675 plunger, and peristaltic designs with turndown to 1000:1, integrated controls, and wet ends in PVDF, PP, 316SS to survive hypochlorite, acids, coagulants, polymers, and more.
- Accuracy: ±1% (or better) at steady state with proper backpressure & calibration
- Turndown: up to 1000:1 with digital drives (e.g., SMART digital)
- Chemistry-ready: PVDF/PP heads, PTFE diaphragms, degassing heads for NaOCl
- Controls: 4–20 mA, pulse, Modbus/Profibus/IO-Link, batch/volume modes
Manufacturers We Represent for Metering
Featured Metering Products
What Makes Metering Different (and When It Beats Other Pumps)
How Metering Pumps Work
- Positive-displacement stroking—fixed cylinder volume; accuracy via stroke length/speed control
- Diaphragm drives isolate the fluid; peristaltics move fluid with a hose squeeze
- Smart drives accept pulse, 4–20 mA, batch, and support turndown up to 1000:1
Where Metering Wins
- Precise chemical feed for pH, ORP, chlorine, coagulation and polymer
- Clean, repeatable dosing at low flows & high pressures
- Degassing heads solve off-gassing NaOCl and similar issues
- Skids & OEM: compact footprints, digital controls, alarm outputs
Best-Fit Metering Configurations by Service
| Service | Ideal Configuration | Recommended Brands | Why It Works |
|---|---|---|---|
| Sodium hypochlorite (NaOCl) | PVDF head, PTFE diaphragm, degassing valve; backpressure 20–30 psi | LMI • Walchem • Grundfos • Emec • Iwaki | Handles off-gassing; maintains accuracy with constant backpressure |
| Acid/base pH control | PVDF/PP or 316SS (per chemistry), PTFE diaphragm; 4–20 mA proportional | LMI • Walchem • Grundfos • Emec • Neptune | Chemical compatibility + proportional dosing from PLC or analyzer |
| Coagulants & flocculants (alum, PAC) | Motor-driven diaphragm, AR check seats; calibration column | Neptune • Grundfos • LMI • Walchem | Stable stroke at higher viscosities; easy verification of setpoint |
| Polymers / high viscosity | Peristaltic metering (hose rated for chemical), low speed, large ID | LMI (KML/KBL) • Emec • Neptune | Shear-friendly, clog-resistant; accuracy maintained at thick viscosities |
| High-pressure boiler & process | API 675 plunger or heavy duty motor-diaphragm; relief valve; metal head | Neptune • Grundfos | Wide pressure window with rigid repeatability; metallic pressure boundary |
Sizing inputs: dose rate (GPH / LPH), setpoint control (pulse, mA), discharge pressure/backpressure, chemistry & temperature, viscosity/SG, duty cycle, enclosure (NEMA) & I/O.
Materials & Performance
Wetted Materials
- PVDF / PP — broad chemical resistance for oxidizers and acids
- 316SS — solvents, heat, and higher-pressure services
- Elastomers — PTFE diaphragm, FKM/EPDM/NBR per chemistry
- Peristaltic hose — Norprene, Hypalon, Viton, PTFE-lined (per fluid)
Real-World Ranges
- Flow: mL/min up to ~100+ GPH per head (multi-head available)
- Pressure: up to 300+ psi (plunger/API 675) and 150–235 psi (motor-diaphragm)
- Turndown: 100:1 typical; 1000:1 on advanced digital drives
- Viscosity: up to heavy polymers with peristaltic or slow-stroke motors
Accessories That Protect Accuracy
- Backpressure valve (keeps constant discharge pressure for stroke repeatability)
- Pulsation dampener (smoothing for meters, analyzers, and long lines)
- Relief & anti-siphon (safety and consistency against elevation changes)
- Calibration column (prove setpoint in mL/min without guesswork)
- Injection quill & foot valve/strainer (clean injection & reliable priming)
- Controllers (Walchem analyzers, PLC/SCADA signals, batch/volume routines)
Metering vs. Other Common Pump Types
| Use Case | Metering (Diaphragm) | Peristaltic | AODD | Centrifugal |
|---|---|---|---|---|
| Accuracy at low flow | Excellent | Great (hose elasticity limits) | Fair (air-set & pulsed) | Poor (not for dosing) |
| High pressure capability | Excellent (API 675) | Fair | Poor | Good (process, not precise) |
| Off-gassing chemistries | Great w/ degassing head | Excellent | Great transfer; dosing varies | Poor |
| Viscous polymers | Good (slow stroke) | Excellent | Good transfer | Poor |
| Sanitary capability | Available | Available | Available | Available |
What We Need to Size Your Metering Pump (5-Minute Worksheet)
- Target dose: GPH/LPH and desired turndown (min/max)
- Discharge pressure & backpressure (include elevation and line losses)
- Chemistry: SDS, temperature, viscosity/SG, off-gassing risk
- Signals: pulse/mA/batch, alarm outputs, local/remote control
- Environment: NEMA rating, enclosure, sanitary/ATEX, skid footprint
Top Metering Lines We Stock (Placeholders)
Send your setpoint, chemistry, and pressure—We’ll return curves, materials, and a complete BOM.
Need Repeatable Dosing—Without Trial & Error?
Send your dose rate, chemistry, discharge pressure/backpressure, and control signal. We’ll return a proven metering package that installs cleanly and stays on spec.
Metering Pump FAQs
How do I keep dosing accuracy stable with a changing system backpressure?
Use a backpressure valve (typically 20–30 psi minimum) so each stroke sees a constant discharge pressure. Pair it with a calibration column to verify mL/min at setpoint.
What’s the best metering technology for off-gassing sodium hypochlorite?
PVDF-head diaphragm pumps with degassing valves work well. For extreme cases, peristaltic metering avoids gas lock entirely.
When should I step up to API 675 plunger metering?
At higher discharge pressures and when you need rigid repeatability with metallic heads and packing systems—common in boiler treatment and process dosing.
Do I need a pulsation dampener?
If you’re feeding flow meters, analyzers, or long small-ID lines, yes—the dampener improves reading stability and protects components downstream.