Selection guide / WETTING
Hydrophilic or Hydrophobic? Start with the Fluid
Distinguish liquid and gas use
Hydrophilicity and hydrophobicity describe how liquids wet a membrane surface. Selection also depends on material, fluid composition, pressure and product construction.
Pre-wetting is part of the process
For products requiring pre-wetting, specify the liquid, sequence, displacement and residual limits. Include these steps in process assessment.
Confirm the condition after cleaning
Cleaning, drying and reuse may change operating conditions. Follow the controlled instructions and validation evidence for the specific product.
Distinguish poor wetting from blockage at start-up
Low flow through a newly installed filter may reflect incomplete wetting, trapped gas or valve state rather than retained particles. Verify the specified preparation and fluid, then observe stabilization after controlled venting. Unapproved wetting-fluid changes or pressure increases can introduce carryover or exceed assembly conditions.
- Record whether the received filter is dry, prewetted or liquid-packed.
- Retain wetting fluid, duration, displacement procedure and stable readings.
Reassess changes in surface condition
Surfactants and solvent mixtures can alter the surface–liquid interaction, and different PTFE surface treatments are not interchangeable. Gas duties require attention to condensation and cooldown; liquid duties require attention to prewetting carryover and any subsequent drying. Evaluate the surface state throughout the use cycle.
- Identify ingredients that can change liquid surface tension.
- Record changes in formulation, wetting and storage separately.
This general guide does not replace controlled technical documents or validation under actual process conditions.
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