Pure Water Crossflow Elements



The use of membranes to selectively remove, separate, or concentrate extremely small substances from water is a technological success story of modern-day times. Membrane processes go beyond conventional filtration.

There are basically four classes of membranes in use today, each removing different types and/or sizes of

substances from the given fluid. The four membrane classes, or separation technologies, are named Reverse Osmosis (RO), Nanofiltration (NF), Ultrafiltration (UF) and Microfiltration (MF).

Although the four classes of membranes look similar, they are functionally unique. Membranes require highly advanced polymer chemistry and manufacturing techniques involving the coating of thin layers of various types of polymers, or plastics, onto backing materials. Depending on the material, process and chemistry involved, either a reverse osmosis, nanofiltration, ultrafiltration, or microfiltration membrane will emerge.

The principal difference between each type of membrane is in the size of the pores, with reverse osmosis
membrane pores being the smallest. Each membrane performs very different functions in varying application environments. In general, RO and NF membranes are capable of separating substances as small as ions from feed streams, while UF and NF membranes typically separate larger molecules. All four membrane types allow water to pass.
The filtration spectrum, illustrated on the following page, shows that membrane separation technology removes

Typically, RO membranes reject at the ionic level, and NF membranes are usually used to reject multivalent and divalent cations while allowing monovalent ions to pass, thus displaying a unique ability to separate differing ions from one another on the basis of their chemistry. UF and MF membranes reject molecules on the basis of size, with UF retaining particles larger than 30 and MF membranes retaining particles larger than 500. UF and MF membranes are typically rated in terms of pore size and porosity, while RO and NF membranes are rated in terms of percent rejection of a specific salt, and in terms of flow.

Trumpler-Clancy, inc. has the ability to cross most manufacturer's membrane filters. Contact us today to save money on your next membrane re-load.