Hydrophilic Syringe Filters

The pores of the microporous membrane act as small capillaries. When a hydrophilic membrane is in contact with water, surface tension-related capillary action causes water to spontaneously enter and fill the pores. In this way, the membrane is easily wetted and allows a large amount of water to flow through the pores. Once wetted, hydrophilic membranes will not allow substantial flow of air or other gases unless they are applied at pressures greater than the membrane's bubble point.

Hydrophilic filters are commonly used with water and aqueous solutions. They can also be used with compatible non-aqueous fluids. Hydrophilic membranes are generally not used for air, gas or exhaust filtration because the filter can block flow if it is accidentally wetted, for example by condensation.