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Aspirator used in serving draught beer
A
cask breather
(sometimes called a
cask aspirator
) is a type of demand valve used to serve
draught beer
. The cask breather enables the empty space created when beer is drawn from a
beer cask
to be filled with
carbon dioxide
from an external source. This prevents ambient air from being drawn into the cask, thus extending the life of the beer by preventing
oxidation
.
[1]
To avoid
carbonation
of the beer, the carbon dioxide gas added by a cask breather is at low pressure, unlike the high pressure gas used to pressurize
keg beer
. Cask breathers are typically used in conjunction with a
pressure regulator
to ensure the gas pressure is sufficiently low.
[
citation needed
]
Before 2018, the use of cask breathers was opposed by the
Campaign for Real Ale
(CAMRA),
[2]
a policy that was changed in April 2018 to allow pubs using cask breathers to be classified as
real ale
pubs and listed in the
Good Beer Guide
.
[3]
References
[
edit
]
See also
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edit
]