| PES membrane | 0.04–0.20 µm; absolute retention commonly specified for critical liquid service | Strong choice for final UPW and chemical filtration when pre-rinsed and validated for ionic cleanliness | 0.05–0.25 bar at 10–20 L/min·m², depending on pore size and construction | Target after validated rinse: TOC ≤10 ppb; individual ionic species typically screened at ≤1 ppb | Good aqueous compatibility; moderate temperature capability, commonly used below approximately 80–90 °C | Suitable only with low-shedding construction, controlled packaging, and installation in an ISO 14644-1 Class 1 environment |
| PTFE membrane | 0.02–0.20 µm; hydrophilic grades preferred for aqueous UPW service | Very strong chemical resistance; hydrophobic grades require wetting and are generally better suited to gas or solvent duties | 0.08–0.40 bar at 10–20 L/min·m², with lower resistance often achieved by larger-pore grades | Target after validated rinse: TOC ≤10 ppb; fluoride and other ions must be specifically verified | Excellent resistance to aggressive acids, bases, and solvents; temperature capability can exceed 100 °C depending on support and assembly | Low particle shedding is achievable; verify support materials, seals, packaging, and particle-release test results |
| PVDF membrane | 0.05–0.22 µm; commonly used for fine aqueous and chemical filtration | Good option for many UPW applications after confirming extractables, wetting behavior, and long-term resistivity stability | 0.06–0.30 bar at 10–20 L/min·m² | Target after validated rinse: TOC ≤10 ppb; monitor fluoride, sulfate, and process-specific ions | Good mechanical strength and broad aqueous compatibility; chemical resistance varies by solvent and concentration | Use cleanroom-compatible packaging and verify particle contribution under actual flow and pressure cycling |
| Polypropylene depth media | 1–20 µm nominal; typically used as a prefilter rather than a final UPW barrier | Useful upstream for particulate loading control; generally not selected alone for final 18.2 MΩ·cm UPW filtration | 0.02–0.15 bar at 5–15 L/min·m², depending on grade and solids loading | Target after validated rinse: TOC ≤20 ppb for prefiltration; ionic profile must be checked for the process | Good resistance to many aqueous chemicals; temperature commonly limited to approximately 80–90 °C | Select low-shedding fibers and sealed edges; avoid exposed media in the final critical zone unless validated |
| Borosilicate glass-fiber depth media | 0.7–3.0 µm nominal; high dirt-holding capacity for upstream clarification | Appropriate for upstream particle reduction only; not normally the final barrier for high-purity UPW | 0.03–0.20 bar at 5–15 L/min·m², increasing with solids loading | Require low-binder or binder-free construction; screen TOC, boron, silica, and particle release | High surface area and good thermal stability; chemical compatibility depends strongly on pH and binder chemistry | Not preferred in the final ISO Class 1 critical path unless particle shedding and fiber migration are specifically controlled |
| Regenerated cellulose membrane | 0.10–0.45 µm; selected for specific aqueous analytical or process duties | Can be used in compatible aqueous streams, but is less broadly preferred for aggressive semiconductor chemicals | 0.05–0.30 bar at 10–20 L/min·m² | Target after validated rinse: TOC ≤10 ppb; screen cellulose-related organics and bioburden where relevant | Good wettability; limited resistance to strong acids, strong bases, and many organic solvents | Use only after cleanroom particle, extractables, and chemical-compatibility qualification |