Sensors provide the perfect head on a pint.

Regulation of dissolved gas is essential for breweries to
achieve the optimum amount of head and maintain the
quality and taste of their beers. Headmaster's instruments
for gas regulation use a range of sensors, to ensure the
perfect pint  

One of the the most important factors in the production of beer and soft
drinks is the amount of gas that is dissolved in the liquid. There are
three gases in the drinks industry which are critical - carbon dioxide,
nitrogen and oxygen. Carbon dioxide is typically found in sparkling water,
beers and lagers - but certain beers also contain nitrogen, which gives
a creamy texture that has become increasingly popular. The third gas,
oxygen must be eliminated as far as possible.

Headmaster has built a range of instruments, using Gems Sensors'
devices, to enable breweries (and soft drinks manufacturers) to calibrate
their analysers and plant, and regulate the gas content of their products.

The calibration svstem operates by producing a constant stream of water
containing a known and displayed amount of dissolved gas. The amount
of gas is controlled by gas/liquid membranes. These establish an
equilibrium between the gas and the liquid in terms of the amount of
dissolved gas in the liquid - which is a function of temperature and pressure.
Accurate measurements for pressure and temperature are therefore critical.

Headmaster use Gems Sensors' 2200 pressure transmitters. A thin film
sensor is atomically bonded onto metal substrate - eliminating drift whilst
offering enhanced sensitivity. The 2200 series offers a static error band
of 0.25%, thermal error band of 1.5% (-20 to +80º C) and has a typical
long term drift of <±0.2%/year.

Signals from the transducers are entered into an analogue computer
which calculates the level of dissolved gas in the water. The water is
then passed on through the analyser in the brewery which should show
an identical reading to the calibrators measurements.

The transducers are subjected to hardness, leak, pressure. thermal
cycling and ageing tests and offer long term mechanical and electronic
integrity. They also meet the requirements of BS5750 and lSO9000,
and resist shock and vibration.

Ken Page, Managing Director of Headmaster, said: "We were looking
for a pressure sensor that was extremely accurate and stable. Gems
Sensors' pressure transducer's were able to provide the right technical
quality to ensure reliable results for our customers, time after time."

The Cellarsteam, also developed by Headmaster in partnership with
Air Products, uses Gems Sensors' FS-3 flow sensors to control dissolved
gas, in draft beer in the pub. It allows full correction of both nitrogenation
and carbonisation even from initially flat beer. The product reduces the
waste and delay of fobbing (or drawing off excess gas at the beginning
and end of barrels).

The flow sensor detects when the beer is flowing and when it ceases.
The piston-type technologv encapsulates a permanent magnet. which
is positioned in the flow path, within the unit housing. When displaced
by the fluid flow, the piston magnetically actuates a sealed reed switch.
A stainless steel spring provides positive piston return as the flow

The FS-3 has out operating temperature of 10 bar at 20ºC and is
supplied in FDA approved materials.

For more information contact:-

GEMS Sensors
Tel: +44(0) 1256 320244

March 2001

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