The current generally accepted method for measuring the air content in a beverage liquid (usually carbonated) is by a non-electronic chemical technique. This invention measures the oxygen component of a beverage gas using a polarographic probe, ultrasonic degassing, a special valving technique, and microprocessor...http://www.google.com/patents/US5220513?utm_source=gb-gplus-sharePatent US5220513 - Gas content measurement in a sealed container of liquid by degassing
