Maintenance. Monitor the pressure across each filter element and change it at a pre-determined pressure drop. Watch for sudden reductions in the pressure differential across the filter, which could indicate a filter is damaged. Pressure gauges upstream and downstream from filters are helpful in providing this visibility.
Ratings. Don’t select filters based on micron size alone; double-check the filter’s capture efficiency at the stated particle size and look for verified performance. The standard for filtration in food and beverage processing is a log 5 reduction, meaning the filter must remove 99.9998 percent of contaminants in its listed micron range. For example, Donaldson Co.’s 0.2-micron sterile liquid and air filters are validate to remove 99.999998 percent of particles at 0.2 micron (the higher log 7 reduction observed in the pharmaceutical industry).
Certification. Look for equipment and products with the 3-A symbol. It means an independent third party verified its sanitary design, including 316/316L gauge stainless steel, a fully drainable, easily cleanable design, and a specified surface finish.
After considering these basic principles, there are other factors to weigh with your filtration provider:
- Depth-loading capacity (retention);
- Number of sterilization cycles the element can safely tolerate;
- How often the element will need changing (filter life); and
- Flow rates, which drive energy costs.
All of these performance factors contribute to total cost of ownership.
The design and maintenance of filtration systems is critical. It can be helpful to obtain a comprehensive evaluation of your system by a qualified process filtration consultant. Also, be sure to work with suppliers who are knowledgeable about filter operation and maintenance needs from end to end, and whose equipment is validated to meet objective standards.
Rojina is an application engineer in the Donaldson’s Process Filtration division of Donaldson
Company, a global provider of filtration solutions for sterile air, gas, liquids, and steam used in the food and beverage, and other processing industries. Reach him at Robert.Rojina@Donaldson.com.