Filter
flask is also known as Büchner flask. It is also known as vacuum flask,
side-arm flask or Kitasato flask. Filter flasks look like Erlenmeyer flasks
in shape, however they are made with heavier walls. They feature a short
side-arm protruding from the neck of the flask. This small side-arm is used
to connect the flask to a vacuum source via rubber tubing, while the top of
the flask is stoppered or fitted with a funnel. Thus the filter flask is
able to hold a reduced pressure without imploding. It makes them perfect for
vacuum filtration.
Filter flasks are also known as Filtering flasks. They are usually used
with some kind of vacuum assembly. Aspirator is the most economical that
connects to the kitchen tap. It can also be used with different types of
funnels such as buchner funnels, thistle tubes and the like. They are used
to speed up filtration by connecting a vacuum aspirator to a faucet. A
slight vacuum is created by the flowing water that pulls the liquid faster
than gravity alone.
Filter flasks are named after the industrial chemist Ernst Büchner.
They are also known as a Kitasato flask, in honor of Shibasaburo Kitasato.
They are like Erlenmeyer flasks attached with an adapter, also called a
side-arm, near the top. The side arm is attached to a rubber hose that is
connected to a vacuum pump or aspirator. As suction is applied, air exits
through the side-arm and a vacuum is created inside the flask. The stopper
used in the filter flasks must have a hole in the center to allow for the
thistle tube to fit through. The thistle tube is inserted in such a way that
its bottom is submerged in the water.
| Types of Buchner Flasks |
Designs |
| Filtering Flask With
Bolt Neck |
|
| Filtering Flask With
Side Arm |
|
| Pear Shaped Filter
Flask |
|
Uses of Buchner Flask
A Büchner flask or filter flask is mainly used in organic chemistry
labs to remove unwanted solids from the liquids. The benefits of using a Büchner
flask over a piece of filter paper held over a beaker is that the solid is
dried as more liquid is sucked off of it by the vacuum.
Features of Filter Flask
- Vacuum Filter Flasks are perfect for field based filtration.
- These highly break resistant filter flasks are easy to decontaminate.
- They are used to speed up filtration by connecting a vacuum aspirator
- They are available in various models.
- The wall of the filter flasks are thicker than the erlenmeyer flasks.
- The thick wall of the filter flask provides it the strength to resist
the pressure difference while holding a vacuum inside.
- The buchner flasks are usually shorter than the erlenmeyer flasks.
