Metering / Dosing Pumps
Metering pumps accurately and repeatably dose chemicals—coagulants, polymers, hypochlorite, caustics, acids, biocides, CIP solutions—into your process. We stock and engineer solenoid‑driven, mechanical diaphragm, and hydraulic diaphragm/API 675 metering pumps from LMI (PD, TD Series, Motor Driven SD), Walchem, Grundfos (DDA/DDE/DME), Neptune, and EMEC. Share your flow (GPH/GPD), discharge pressure, viscosity, chemical compatibility, and control signals (4–20 mA / pulse / Modbus) and we’ll size the right pump—often shipping the same day from California, Washington, and Arizona.
Need help choosing between solenoid, mechanical, or hydraulic diaphragm? Talk to a dosing engineer—most quotes leave our inbox within one business hour.
Quick Selector: Technologies & Manufacturers
| Manufacturer / Series | Technology | Typical Capacity Range* | Max Pressure* | Turndown / Accuracy | Controls / Comms |
|---|---|---|---|---|---|
| LMI (PD Solenoid, TD Series, Motor Driven SD) | Solenoid diaphragm (PD, TD) & Motor‑driven diaphragm (SD) | Up to ~300 GPD (solenoid ranges) / higher for SD | Up to ~300 PSI (series‑dependent) | Up to 1000:1 / ±1–2% | Manual, pulse, 4–20 mA (series‑dependent) |
| Walchem (EWN, EZ, IX) | Solenoid diaphragm / digital | Up to ~500 GPD | Up to ~300 PSI | 1000:1 (IX) / ±1% | 4–20 mA, pulse, Modbus, BACnet (select) |
| Grundfos (DDA / DDE / DME) | Digital solenoid diaphragm | Up to ~60 GPH (DDA/DDE) / series dep. | Up to ~232 PSI | Up to 3000:1 / ±1% | 4–20 mA, pulse, Profibus/Modbus (select) |
| Neptune (Hydraulic/API 675) | Hydraulic diaphragm (API 675) | Low to high GPH (wide range; API duty) | High pressure (hundreds to 3,000+ PSI) | Typically ±1% accuracy | 4–20 mA, pulse, explosion‑proof options |
| EMEC (AMS, PRISMA, etc.) | Solenoid / stepper‑driven diaphragm | Up to ~250 GPD | Up to ~290 PSI (series dep.) | Up to 1000:1 / ±1% | 4–20 mA, pulse, Modbus (select) |
* Capacities & pressures vary by series/model; we’ll confirm against your exact duty.
Why Engineers Choose Our Metering Pumps
- Accuracy & repeatability: typically ±1% or better when correctly sized & valved
- Huge turndown ratios (up to 3000:1) for variable process loads
- Chemical compatibility: PVDF, PP, PVC, 316SS, PTFE diaphragms, ceramic balls
- Full controls stack: 4–20 mA, pulse, Modbus/Profibus, batch/stroke counters, alarms
- API 675 hydraulic diaphragm options (Neptune) for high pressure / process duty
How We Size Metering Pumps (So You Hit Setpoints Without Hunting)
1) Dose Rate & Turndown
We calculate your required GPH/GPD at minimum, normal, and maximum load, then select a pump that runs near its midrange (best accuracy) while meeting your turndown and ±1% repeatability targets.
2) Discharge Pressure & Backpressure Valves
Correctly defining system pressure ensures you don’t undersize. We frequently add backpressure / anti‑siphon valves on low‑pressure lines for stability and accuracy.
3) Chemical Compatibility & Temperature
Heads: PVDF, PP, PVC, 316SS. Diaphragms: PTFE, EPDM. Balls/seats: Ceramic, Hastelloy, 316SS. We select based on SDS, temperature, and abrasion risk.
4) Controls & Signals
Need closed‑loop dosing (pH/ORP/Cl), remote setpoint control, batching, or PLC integration? We’ll spec pumps with the right 4–20 mA, pulse, Modbus/Profibus features and alarms.
5) Pulsation Dampening & Instrument Protection
We add pulsation dampeners, pressure relief valves, backpressure valves, and calibration columns to stabilize flow, protect analyzers, and verify dose rates.
Brand / Series Snapshot
| Brand / Series | Head Materials | Valving / Balls | Features | Typical Uses |
|---|---|---|---|---|
| LMI PD (Solenoid), TD Series, Motor Driven SD | PVDF, PVC, 316SS | Ceramic, Hastelloy | PD/TD: solenoid precision; SD: motor‑driven for higher flows/pressures | Water/wastewater, cooling towers, boiler feed chem, industrial dosing |
| Walchem EWN / EZ / IX | PVDF, 316SS (select) | Ceramic, Hastelloy | Digital stepper (IX), high turndown, comms options | Industrial water, cooling towers, process dosing |
| Grundfos DDA / DDE / DME | PVDF, 316SS (select) | Ceramic, 316SS | Digital dosing, 3000:1 turndown (DDA), SmartFlow | Precise low-flow dosing, water treatment skids |
| Neptune (API 675) | 316SS, Alloy 20, Hastelloy | SS, Tungsten Carbide, others | Hydraulic diaphragm, high pressure, API compliant | Oil & gas, chemical process, high pressure dosing |
| EMEC (AMS / PRISMA) | PVDF, PP | Ceramic / Hastelloy | Stepper-driven precision, advanced interfaces | Pools, industrial water, OEM skids |
Common Metering Pump Applications
- Water & Wastewater – hypochlorite, bisulfite, alum, caustic, polymers
- Chemical Processing – acids/caustics, inhibitors, catalysts, pH control
- Power / Boiler Feed – oxygen scavengers, phosphate, amines
- Food & Beverage – CIP/COP chemicals, sanitizers, additives
- Cooling Towers – biocides, scale/corrosion inhibitors
- Oil & Gas / Refining – API 675 high-pressure dosing
Accessories to Make Dosing Accurate & Stable
- Backpressure / anti‑siphon valves
- Pulsation dampeners & pressure relief valves
- Calibration columns & injection quills
- Leak detection, diaphragm rupture alarms
- Bulkhead fittings, tubing, degassing heads
Send your GPH/GPD, PSI, chemical SDS & control needs—quotes usually in < 1 hour.
Metering Pump FAQs
What’s the difference between solenoid, mechanical, and hydraulic diaphragm metering pumps?
Solenoid pumps (LMI PD/TD, Walchem, Grundfos, EMEC) are compact, precise, and ideal for low‑to‑moderate flows/pressures. Mechanical diaphragm pumps (e.g., LMI SD) handle higher flows/pressures. Hydraulic diaphragm/API 675 (Neptune) deliver the highest pressures, best for process/oil & gas.
Why do I need a backpressure valve on a metering pump?
Metering pumps require a stable discharge pressure to dose accurately. A backpressure/anti‑siphon valve prevents overfeeding and siphoning in low‑pressure or vacuum lines.
How accurate are metering pumps?
Properly sized and valved metering pumps typically deliver ±1% or better repeatability across their controlled turndown range.
Can metering pumps handle polymers or viscous fluids?
Yes, but viscosity correction and proper valving (backpressure, pulsation dampening) are critical. In some cases, progressive cavity or peristaltic pumps are better for high‑viscosity polymers.
Do you provide API 675 compliant metering pumps?
Yes—Neptune hydraulic diaphragm pumps meet API 675 and are ideal for process, refinery, and oil & gas dosing at high pressures.