COOLANT FILTRATION LOOKS AT MEDIA MICRON RATINGS DIFFERENTLY FROM OTHER FILTRATION APPLICATIONS

Filter media selection for coolant filtration does not use micron ratings as a major criteria. There is much more to consider. The use of micron ratings for media is more helpful on applications where there is relatively little contamination and where the particle size range is narrow. For example a hydraulic system is a sealed network and the amount of solids it experiences is low and the particles sizes are very small. Therefore, a filter engineer will select a media based on micron ratings because the bare media has to intercept the fine particulate.

However, most coolant filtration applications are on systems where the solids are generated on purpose and usually have a higher ratio of solids to liquid. Also, the particle sizes would span a wider range. Since most coolant filtration applications, use a filter which allows a "cake" of solids to accumulate on the media, the cake is the actual filtering medium and can yield cleaner fluid than the media by itself. The cake is a simulated "sand " bed. Because of this the media is selected for its ability to intercept the larger particles in the range and hold them so the finer particles are trapped to form the cake. Permeability is a factor in this selection since flow must be maintained as the cake grows in thickness and tightness.

Applying a media with a small micron rating for metalworking applications usually results in a higher operating cost for the media. For example; often a request is made for a 5-micron fabric to clean a fluid used for rugged metalworking applications such as rough grinding. 5-micron barrier is too tight and the filter will blind quickly and replace the media frequently at a high cost. The significance of this statement is further understood when it is realized that the human eye can not see a 5-micron particle. The range of visibility starts at about 29-micron.

Harrigan Solutions understands the selection process for coolant filtration and offers engineering know-how for these applications. They also sell or rent new and used filters when their customer needs a way to overcome an economic obstacle. Harrigan Solutions has as a trained staff to provide service on the filtration equipment ( including centrifuges) which can be tailored to the plant's needs. For more information contact Bill Harrigan at 1-888-685-9603. His email is bharrigan@harrigansolutions.com. The website is www.harrigansolutions.com/index.htm.