VisiFerm DO optical sensor for measuring dissolved oxygen in beer

If large amounts of dissolved oxygen are present in finished beer, oxidation processes take place. These oxidation processes negatively affect the beer’s flavour and cause premature product ageing. To ensure the best product quality, taste and a long shelf life, the amount of the dissolved oxygen must be minimised. This requires considerable technical effort and a continuous oxygen content monitoring.

The monitoring of dissolved oxygen content has traditionally been done with amperometric sensors. Amperometric monitoring is done with the help of electrochemical sensors according to the Clark Principle: the content of dissolved oxygen is determined by means of a current flow in the sensor’s measuring chamber. However, this amperometric method has known limitations, such as a difficulty with inline measurements typical of large filling lines due to Clark sensors’ susceptibility to breaking down and requiring a lot of maintenance.

Hamilton has developed an alternative to the amperometric method. Claimed to be the first standardised 12 mm sensor, the VisiFerm DO measures dissolved oxygen optically using a method based on oxygen-dependent luminescence.

VisiFerm DO optical sensors optimise the brewing process in several ways. After CIP cleaning, the optical sensors can be re-used faster than with an amperometric sensor. As a result of this, the quantity of rinsing product used and afterwards discarded can be reduced. Moreover, the VisiFerm DO sensors are also less susceptible to breakdown and need less maintenance than amperometric sensors, as they have only one part subject to wear: the sensor cap. The sensor cap must be changed every four to eight months, and the replacement and recalibration only takes a few minutes.