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Clarification and Prefiltration Processing Steps

Surface view of a used Bevigard filter 
Surface view of a used Bevigard™ filter
Bioburden and unwanted particles can affect your downstream product quality and plug your membrane filter, reducing its effectiveness and service life. Clarification and prefiltration are critical steps that remove these contaminants early in the process, extending the life of your final filters. The economic advantage of extending the life of your more expensive membrane filters is far greater than the cost of prefilters.

Merck offers a wide range of prefilter cartridges and capsules to meet your specific application needs. Contact a Merck Specialist to help you select the best filters to meet your specific needs.

Selecting a Clarifying or Prefilter

Where to Use a Prefilter

For applications where 99 to 100% retention of contaminants above a specified pore size is not required, clarifying filters and prefilters are recommended. To guarantee microbial retention, a membrane final filter must be used.

Selecting a Clarifying Filter and/or Prefilter 

Selecting the proper clarifying and/or prefilter is based on your individual application needs. Our specialists can assist you in determining which filters will yield your desired product quality, be the most efficient and cost effective for your particular application.

Choose filters based on the retention efficiency required for your filtration process as a whole. First, decide on your final filter, and then select your clarifying and/or prefilters. Working this way provides you with the best combination of retention and capacity. By selecting the proper pore size rating, you will ensure the required dirt-holding capacity for your application.

A non-fiber releasing membrane-like prefilter could be used as a final filter. However, the fiber matrix of these filters may occasionally unload retained contaminants into the filtrate if subjected to extreme pressure fluctuations, flow surge, or fluid “hammer.” These phenomena are not uncommon in the high flow/high volume piping systems beverage manufacturers use, and are usually caused by pump on/off cycling, quick closing valves, and other process flow control devices.

In certain cases, it may be more practical and cost-effective to use a clarifying filter followed by more retentive prefilters. This allows each filter in the train to be used to its maximum capacity, removing as much contamination as possible.


Clarifying Filters Prefilters
Polygard®-CR Polygard®-CN
Polygard®-CT Polygard®-CR
Polygard®-CN Polygard® Trap
Polygard® Trap Polygard®-CE
Polygard®-CE Clarigard®
Clarigard® Bevigard™-L
Bevigard™-L Bevigard™-P
Bevigard™-P Bevigard™-M
Opticap® XL and XLT with Milligard®  

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