Filtering Out Confusion

RO is used in desalination of sea water, purification of potable water and in manufacturing processes in which high purity water is required.

Filter Efficiency

Two primary methods of rating filter efficiency are nominal rating and beta ratio.

Nominal filtration rating generally refers to the efficiency of a filter at removing particles of a given size. Most manufacturers refer to nominal efficiency for removal of particles in the 95 to 98 percent range. However, efficiencies as low as 50 percent have been referred to as nominal.

A more rigorous method of reporting filter efficiency is Beta Ratio, which describes the ability of a filter to remove particles of a given size from a fluid stream. See Fig. 1 for the formula to derive efficiency from Beta Ratio.

Upgrading Your Filtration System

It’s important to consider liquid filtration as a necessity to ensure the integrity of your process, your equipment and your finished product. Don’t risk shutting down a multi-million-dollar piece of equipment because someone “skimped” on a $50 filter. Keep in mind that the “costs” associated with liquid filters include not only the filter itself, but also installation, operating and maintenance costs.

Start by quantifying and qualifying your filtration goals: Higher product quality, manufacturing cost improvement, environmental regulation compliance, reduced raw material consumption and reduced system wear and maintenance. Benchmarking the performance of your current filtration system before making changes is a good way to gauge improvement against goal. Because liquid filtration is such a complex process, it is important to seek help from a qualified expert. Filter manufacturers and distributors have much more expertise than even the most seasoned systems or maintenance engineer, and help from these experts is often available for free.

Ronald Cox is director of marketing for Kimberly-Clark Filtration Products (Roswell, Ga.) and can be reached at 770-587-7897 or [email protected].