Which Materials Are Available for Miniature Diaphragm Pumps? Selection Considerations
Compare pump-head, diaphragm and valve materials, then check fluid composition, concentration, temperature, exposure time and cleaning conditions before selecting a configuration.
When selecting a miniature diaphragm pump, consider the materials in contact with the fluid as well as flow, pressure and installation dimensions. Compatibility requires particular attention when handling reagents, cleaning solutions or waste liquids. FOREACH offers the following two main material combinations; availability depends on the selected model.
| Pump head | Diaphragm | Valve |
|---|---|---|
| PPS (polyphenylene sulfide) | EPDM (ethylene propylene diene rubber) | EPDM (ethylene propylene diene rubber) |
| PPS (polyphenylene sulfide) | PTFE (polytetrafluoroethylene) | FFKM (perfluoroelastomer) |
Both combinations use a PPS pump head; the diaphragm and valve materials differ. Evaluate all three as a complete set of materials in contact with the fluid.
1. Pump head: check the pump chamber as well as the diaphragm
The pump head forms the chamber that holds and transfers the fluid, so its material must also be compatible. These FOREACH combinations use PPS pump heads. Even with a PTFE diaphragm and FFKM valves, confirm that PPS is suitable for the actual fluid.
A PTFE diaphragm does not mean that every wetted component is PTFE. Review the complete wetted-material information instead of judging the whole pump by one component.
2. Diaphragm: fluid contact and repeated movement
The diaphragm moves back and forth to change chamber volume, enabling suction and discharge. Material selection must consider fluid compatibility and repeated movement under actual operating conditions. FOREACH offers EPDM diaphragms with EPDM valves, or PTFE diaphragms with FFKM valves.
For purified water, the EPDM diaphragm and valve combination can be an initial candidate, subject to the model's flow, pressure and operating requirements. For reagents and cleaning solutions, assess both combinations against the actual composition. Broad descriptions such as aqueous liquid, acidic liquid or organic solvent are insufficient. Changes in concentration or temperature require a renewed assessment.
3. Valves: assess them together with the diaphragm
Valves help control flow direction. Their opening, closing and sealing affect suction and discharge. They also contact the fluid and require a separate compatibility check even if the diaphragm is suitable.
FOREACH uses EPDM or FFKM valves in the two combinations shown. Confirm pump-head, diaphragm and valve materials together before considering the complete pump suitable.
4. Operating conditions to confirm before selection
Start with the actual application and provide the following information:
- Composition and concentration: identify the liquid, solvents, additives and any mixed waste streams.
- Temperature: specify transfer and cleaning temperatures and check the model's fluid-temperature range.
- Exposure: distinguish intermittent transfer, continuous operation and liquid remaining in the chamber during shutdown.
- Cleaning: identify the cleaning agent, frequency, temperature and duration of each exposure.
- Operation: specify actual flow, working pressure, start-stop frequency and daily operating hours.
Cleaning is easily overlooked: the working fluid and cleaning solution may differ, and both need compatibility assessment. Also check fittings, tubing and any other seals that contact the fluid in the specific design.
5. Validate with the actual fluid
Successful purified-water testing does not establish long-term performance with the actual reagent. After initial selection, test with the real fluid under conditions close to the installed application and within the model's limits. Check flow, suction, sealing and material condition after operation.
For FOREACH pump selection, provide fluid identity and concentration, operating temperature, cleaning method, and flow and pressure requirements to match a model and material combination.