Four common metering pump technologies — solenoid, mechanical diaphragm, hydraulic diaphragm, and piston/plunger — differ in flow rate, pressure, accuracy, and cost. Select the right technology first, then move on to model and material.
Characteristics of Each Technology
- Solenoid (electromagnetic): an electromagnet drives the diaphragm in pulses. Low flow rate, moderate pressure, low cost, compact — suitable for chemical dosing in small-to-medium water treatment applications.
- Mechanical diaphragm (motor-driven): motor + cam drives the diaphragm. Higher flow rate and stability than solenoid, medium pressure — widely used for water treatment and industrial applications.
- Hydraulic diaphragm: hydraulic oil transmits force to the diaphragm → handles higher pressure, good accuracy, durable diaphragm (not under direct pressure).
- Piston/plunger: piston pumps directly. Very high pressure and large flow rate, high accuracy — for oil & gas and high-pressure processes; sealing must be considered for corrosive chemicals.
Quick Comparison Table
| Criteria | Solenoid | Mechanical Diaphragm | Hydraulic Diaphragm | Piston |
|---|---|---|---|---|
| Flow rate | Low | Low–medium | Medium–high | High |
| Pressure | Moderate (~≤20 bar) | Medium | High | Very high (up to ~250 bar) |
| Accuracy | Good | Very good | Excellent | Excellent (API 675) |
| Cost | Low | Medium | Higher | High |
| Suitable for | Small-scale water treatment | Water treatment & industrial | High-pressure processes | Oil & gas, high-pressure |
Table is indicative — specific flow rates/pressures vary by model. Confirm with the manufacturer’s datasheet.
Which Type to Choose?
Chemical dosing for small water treatment flow rates on a tight budget → solenoid. Need greater stability and a wider flow range → mechanical diaphragm. High pressure or high accuracy required → hydraulic diaphragm. Very high pressure, large flow rate, oil & gas → piston meeting API 675 standard. Technology selected? See next: how to size a metering pump correctly by flow rate and pressure.
Standards & Material Considerations
For oil & gas applications, prioritize pumps meeting API 675 (accuracy up to ±1%); explosive environments require ATEX-rated units. Pump head material (PVC/PP/PVDF/PTFE/SS316L) should be selected according to the chemical — see the material range on the metering pump page.
Thái Khương Pumps is an authorized distributor of Doseuro (Italy) metering pumps covering all 4 technologies. Submit a request for technology and model consultation.
