Foam has the appearance of a simple material, partly because we are all familiar with it, whether in the form of bath foam, bubbles in a milkshake or the head on a glass of beer. However, in reality, foam is a very complex, dynamic material. Most common foams are an unstable, two-phase medium of gas and liquid with a structure consisting of gas pockets trapped in a network of thin liquid films and plateau borders.
Foam arises in many industries and can have a complex set of causes. It can be produced biologically, as in Anaerobic Digestion, brewing, or where filamentous bacteria such as Nocardia are present. It can arise through the cleansing of wastewater, or as a result of cleaning starchy vegetables. It can be an essential part of the production process or an unwanted side-effect.
Why Specialised Foam Control Technology Matters
We need to understand why it is so difficult to measure foam and why so many normal level measurement technologies fail when used in this application. One of the most import reasons is that foam itself generally only contains 1% liquid and 99% gas, making measuring the liquid component with a traditional liquid device near impossible. This is why regular liquid probes are unsuitable and cannot be relied upon to accurately detect foam. At Hycontrol we have been developing level sensors for over 35 years, and we know that 'traditional' level technologies cannot be relied upon for consistent performance in this critical application.
Hycontrol foam sensors have been designed specifically for the measurment of foam. Unlike competing products, they are not simply liquid level sensors which have been adapted or modified for this purpose (and are unreliable for the reasons stated above). Crucially, they have the high sensitivity required to measure all types of foam.
How Hycontrol Foam Probes Work
Hycontrol foam probes work on aqueous (water-based) foam by utilising an impedance measuring principle. This principle works by passing a small alternating electric current at a very low voltage through the foam into the liquid or the container wall. By measuring the level of the current flowing, we can determine if the foam is present and calculate its density. The probes provide efficient and cost-effective foam control across a wide range of water-based process applications. Each stainless steel sensor can be customised to suit the requirements of your process. Different heads and process fittings are available, with standard insertion lengths of up to 3 metres (for a 20 mm diameter probe).
Probes can be supplied with up to three separate alarm points as required. This flexibility makes Hycontrol the first choice for the widest range of foam applications. The sensors are hygienic and steam sterilisable, and by utilising Hycontrol's patented IMA Sensing® technology, they can discriminate between the residual build-up of product along the sensor and the foam created during the process. Thus, the sensors can continue to efficiently monitor foam levels regardless of how fouled the sensor may become.
Measuring foam is one thing, but it is also vital to avoid false readings caused by the build-up of foam and other substances on the probe. IMA Sensing® allows the reliable measurement of foam even when a sensor is covered with a thick sticky layer of fouling. Learn more about this technology by following the link below.