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Hollow fiber membranes work in exactly the same fashion as the
flat sheet membrane you are familiar with.
Filtration takes place through the wall of the fiber and the filtrate
is passed through the lumen (inside diameter) of the fiber. Because
the hollow fiber takes up less space, hollow fiber membranes can
pack more surface area into a given module than the flat sheet type
filters. As an example, one of the more popular small volume media
filters on the market from our competitor has a flat sheet membrane
wrapped into a cylinder and contains 10 Sq cm of surface area. The
MediaKap® 10 has a surface area of 100 Sq cm.
Spectrum makes two hollow fiber membranes for media filtration.
Both fibers are rated for 0.2 µm pore size. The MediaKap® series
contain standard fiber and are designed for media without serum
and aqueous buffer solutions. The MediaKap® Plus series contain
a high performance fiber which have significantly greater throughput
and is intended for media with serum and partially soluble nutrients
(i.e. soy broth, BSA, yeast extract). Typically, the MediaKap® 5
will filter 5 liters of DMEM in about 15 minutes. The MediaKap®
5 Plus will filter 5 liters of DMEM with 10% foetal bovine serum
in about 20 minutes.
Another feature make MediaKap® unique is the autovent. The fiber
bundle in each MediaKap® contains one hydrophobic fiber which acts
as a downstream vent. When air gets into the line, it passes harmlessly
downstream instead of filling the housing and blocking flow. Because
its automatic, the end user does not have to remember to manually
vent the filter as is necessary in flat disk filters. Also the vent
fiber is 0.2 µm so the air passing downstream is sterile and will
not contaminate the downstream filtrate.
The MediaKap® is a pressure filter. It is intended to operate
with a peristaltic pump or a pressure vessel. All sizes come with
an attached filling bell. In addition the smaller sizes are available
without bell for in-line service.
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