Air-operated double diaphragm pump
Two diaphragms driven by compressed air through a shuttle valve, with no motor, no engine and no electrical parts. Used where a spark cannot be tolerated or the pump will be submerged.
Features
- With no electrics it can be fully submerged or used in a location where ignition sources are prohibited.
- Flow is controlled simply by throttling the air supply, which gives a genuinely variable duty with no control gear.
- Stalling against a closed discharge is harmless — the pump simply stops and restarts when the line opens.
- Air consumption is substantial for the flow delivered, so the site compressor has to be sized to include it.
- Wetted materials are selected to the liquid, and body and diaphragm options cover water, fuels, slurries and mild chemicals.
- Exhausted air is cold and wet, which can ice the exhaust in winter unless a lubricated or heated supply is used.
Specifications
| Figure | Typical range | Unit | Why it matters |
|---|---|---|---|
| Maximum flow | 3 - 30 | m³/h | Throttled freely by the air supply. |
| Air consumption | 200 - 900 | l/min | Must be added to the site compressor's load. |
| Air supply pressure | 4 - 7 | bar | Sets both flow and discharge pressure. |
| Wetted materials | cast iron / polypropylene / PTFE | Selected to the liquid, not just the solids. | |
| Maximum discharge head | up to 70 | m | Roughly equal to the air supply pressure in bar × 10. |