Page 24 - Thirst Magazine Issue No. 3 Coffee & Tea

DISPENSING
In the simplest possible terms there are three basic ways of getting beer from storage to
glass: Gravity, Pulling or Pushing.
TAP AIR PUMP
An on/off valve hammered An electric air pump
into a wooden cask that draws beer from
near the bottom with the the cask in place
cask laid on its side. of a beer engine.
TAP – All beer is essentially dispensed via a
tap of varying kinds, but the original tap was
just that, a simple on/off valve hammered into
a wooden cask near the bottom when the cask
was laid on its side. When open, the valve would
dispense beer with nothing more than gravity
doing the work. It was a simple system but
one that required the bar to have the beer casks
lined up behind the bar on a rack so the barman
could simply turn and pour an ale directly from
the cask, something that is rarely seen today
as modern dispensing systems allow kegs to
kept out of sight below the bar or in a different
room altogether.
AIR PUMP – Although rarely seen these days,
some pubs in Northern areas of the UK used
to use an electric air pump to draw the beer
from the cask. These could be recognised
as the handle on the tap was engaged but
not “pumped” up and down as the beer was
dispensed.
CO2 / NITRO – The most common way of
serving beer in modern bars around the world is
using a gas, usually carbon dioxide or nitrogen,
to pressurise the keg so when the bar tap is
opened the beer is forced from the keg, through
the line and out of the tap. To do this a cylinder
of gas is connected to a “coupler” on top of the
keg which allows gas in and beer out through a
separate valve.
CO2 vs Nitro
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FEATURE_WhatIsDraftBeer.indd 24
CO2 / NITRO HAND-PULLED
Pressurised with gas, A handle which
the beer in the keg is creates a vacuum
forced through the tap when pulled down,
when opened. drawing beer from
the cask.
HAND-PULLED – The hand-pulled tap, also
known as a Beer Engine, is a device invented in
1688 by Dutch inventor John Lofting who was
living in London at the time. While working
on an early fire engine design, he realised his
device could be used to draw liquids other than
water. The design was refined into a specific beer
dispenser, the “Beer Engine”, by Joseph Bramah
in 1797. Over the next few centuries it became
what we know today, but the basic principle
has remained the same. A handle, normally
attached to the bar, is pulled downwards, which
in turn raises a piston in a chamber roughly the
volume of half a pint. This creates a vacuum
in the chamber which sucks or pulls the beer
through a pipe or “line” from the cask, which
could be located under the bar or in a completely
different room.
Each pull of the handle draws the beer into
the chamber and out of the tap into the glass.
A slow, steady pull should draw half a pint so
your pint glass will be filled in two pulls with a
little extra pull to top up the head on the beer.
The cask itself has a secondary “spile” hole at the
top which allows air into the cask as the beer
is drawn from it to make sure the beer flows
properly. (The same reason you put two holes
in a can of condensed milk). To avoid spoilage,
once tapped, a cask ale should be consumed as
quickly as possible and certainly within 3 days.
19/9/2017 8:16:58 AM