One family of products that Filter Products Company has extensive experience developing is centrifuge strainer bags (also known as a centrifuge liner) used in the botanical extraction process. Often, the end product of these processes is meant for human consumption, so we ensure the materials used meet FDA guidelines under 21 CFR 170.39 for direct contact with food, beverage, and potable water applications.
To begin the centrifuge liner design process, please send pictures of the bag design that is currently being used. Even if there are substantial design changes required, it is helpful to have a reference point for both parties (Filter Products and our customer) to work from.
If you are looking for centrifuge bags for Delta (Prospiant) centrifuges, please visit this page.
If this is an entirely new application, we’ve provided a general overview of the details that we will need to develop the new product with you.
A detailed description of the application is necessary. We’re happy to schedule a conversation about the process and its outputs. This will provide Filter Products with critical information about the content and composition of the bags; an understanding of the anticipated flow rates and duty cycles; and the µm rating required for optimal performance.
With the technical objectives established, we can focus on filtration fabric selection and then quickly transition to defining the shape and features of the filtration bag. Below are illustrations of the three centrifuge designs we see most often.
Centrifuge bag with a cone bottom and a flanged top.
This style does not have a covered top, and is held up by pinching the fabric flanges at the top. For these applications the textile liner is also an open-top design. (Note: Most centrifuge bags in the botanical extraction market have a zipper closed top, but this is a common industrial design.)
Centrifuge bag with a cone bottom and a zipper closed top.
The cone bottom is more popular with larger centrifuges that are over 20” in diameter. The zipper and handles can make handling these large bags easier and reduce the likelihood of spilling the contents. The handles pictured in this illustration were specially designed for the customer’s application and are not necessary for most extraction applications.
Centrifuge bag with a flat bottom and only a zipper closed top.
This is a popular design for smaller centrifuges. Available with or without handles, this design is easier to handle because of the small size. While the size may seem too small to be efficient, this configuration is very popular in extraction applications with the value of the plant matter is relatively high, so the quantity of material being processed in a given batch is comparatively low.
General Design Guidelines
Centrifuge bags must be sized so that the bottom and – most critically – circumferential surface of the bag are fully supported by the walls of the centrifuge basket. The side of the bag should completely cover the inner wall of the basket without stretching or bunching the fabric. Stretching the fabric during centrifugation will shorten the life of the liner, and possibly result in failure during use. Significant bunching of excess fabric will result in load imbalance.
It is also advantageous to make closed-top the centrifuge bags a couple of inches shorter than the inner height of the centrifuge basket. During centrifugation the top of the bag tends to bow upwards and if this is not accounted for the lid of the bag will fail due to wear against the inner lid of the equipment.
While popular in other extraction applications, a drawstring closure is not recommended for centrifuge applications because the cinched-closed bag is not nearly as uniform as a zipper-closed bag. The long tails of the drawstring could also become extremely problematic in a centrifuge application.
Please use the form below to share information about your centrifuge application with us.
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