[QUOTE]Originally posted by Pradeep:
"The electrostatic oil cleaning is slower process than mechanical filtration."
Comments: Not true. The particle separation process depends on flow, and most electrostatic filters are LOW FLOW systems for a reason. That’s why they can collect small particles. If you’d run high flow through them then the efficiency would tremendously drop, because the electrostatic forces that holds them in the filter would be overcome by the kinetic energy of oil and particles would be washed away back into oil sump. On the other hand, if you’d run approx 3-micron mechanical depth-type filter at the same flow as an electrostatic (e.f. 1gpm), the results would be pretty competitive.
"However, the cost of fine filtration even upto 5 microns using mechanical filtration is expensive operation as the dirt holding capacity of fine filtration elements is very limited and its price much higher as compared to collector media of electrostatic oil cleaner. We have achieved results uptp NAS class 5 cleanliness by using EOC. Hence EOC is an effective off-line cleaning equipment for hydraulic systems/machines."
Comments: That may be the case in India. In the US, most of depth-type mechanical filters have comparable dirt holding capacities as some of the best electrostatic filters. Also, the price of a collector media of electrostatic oil filters varies, but in general, it ranges from being slightly higher than of the mechanical-type filters, to being competitive.
In general, the choice of using one technology or the other and sizing them properly depends primarily on the particularity of the application this filter system will be use for. Factors to consider, among other things, include the rate of particles ingression (environment), degree of moisture present in oil (environment and/or the system), the rate of wear generation (the system), oil viscosity, and type/size of contaminants being targeted (desired cleanliness level). I have personally noticed high degree of disappointment some folks have towards filters for reason that has nothing to do with the performance of filters, and should be blaming themselves instead. Because they never knew, or considered and insisted on factors (mentioned above) when choosing filters, and ended up with an inadequate filter. When this is combined with a greedy salesman (selling them what is cheaper and what customer is willing to pay, and disregarding the fact that the sold unit is grossly undersized for the application), the final outcome is obviously disappointment. A bit of knowledge goes a long way. Making blanket statements could be misleading, because what works in your application (well, nobody knows what that is as you didn’t bother to mention it), may not work for someone in mining or paper industry.
Also, it does not help to lump all the equipment of all manufacturers out there of either technology in the same bag and pass a judgment favoring one system over another. There always were and will be the "Good, Bad, Ugly" in this field, just like in every other field. Some are perfectionists always striving to break new grounds in the field, and there are others that are driven to make a quick buck. Therefore, the conclusions and judgments of the performances should be more specific.