Duran® Filtering Flask 20L



Filter Flask - Duran®

A filter flask (sometimes called a Büchner or vacuum flask, suction flask, or even side-arm flask) is a piece of laboratory glassware with an attached hose barb for connecting a flexible hose/tubing or a vacuum pump / filtration pump for vacuum filtration.

Unlike some smaller, Erlenmeyer Flask varieties, this product is a larger format, carboy-style filter flask. It is commonly used for filtering or removing solvents under reduced pressure.


  • Thick-walled, rugged glass
  • Sturdy construction
  • Designed for medium-to-large volumes of liquid
  • Can withstand vacuum pressure

With its thick glass walls and sturdy construction, this product is perfect for filtering medium-to-large volumes of liquid. The rugged design means that it is able to easily withstand the pressure of containing a vacuum, without imploding.

Can be used in conjunction with a Büchner Funnel.

When coupled with filter paper and a Büchner Funnel, these filter flasks are everything you need to quickly perform vacuum filtration in your laboratory. The filter paper catches any unwanted residue or particles, and when moistened, forms a tight seal with the porous funnel below it. The suction of the vacuum pulls the paper into the funnel, and the holes are too small to let anything but the filtered liquid pass through.

Perfect for medium-to-large operations.

We carry a selection of the most popular sizes, from 3L all the way up to 20L for larger laboratories. The plastic hose connection can be replaced in case of breakage.

Pictured on the right is the 20L version.

Meets safety regulations.

Manufactured according to the strictest standards, Duran® products meet stringent safety and product regulations. Made from borosilicate glass type 3.3, they were designed to have maximal thermal resistance. They also adhere to the the ISO 6556 protocol.

Uses of filter flasks:

These flasks are used heavily in commercial labs to aid in rapidly filtering solutions. The attached side neck allows for a vacuum pull, which can help you achieve faster results than traditional, gravity-based filtration.

Note: This filter flask will most likely require a filter adapter or a universal silicone stopper to function correctly in your lab. 

Fun fact: These products are sometimes called a ‘Kitasato Flask’, in honor of scientist Kitasato Shibasaburō.

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