Hamilton VisiFerm DO optical sensor for 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 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 method has 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. Measurement with the sensors is said to be always identical and stable and the process is not delayed by stop-of-flow effects - thus, filling can resume at any time.

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 optical 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.