The BUBBLES project brought together industrial, research and academic partners from four European countries with the common aim of delivering an on-line air detection system for use on flowing casting slips. Intermediate objectives included, first, the establishment of basic concepts behind the operation of such a detection system. Secondly, a prototype instrument had to be designed and manufactured. Thirdly, extensive field tests had to be conducted.

According to Dr Graham Small, project co-ordinator at CERAM Research in the UK, the detection system was to be based on newly developed ultrasonic techniques. Extensive laboratory trials carried out by the Institute of Sound and Vibration Research (ISVR) at Southampton University in the UK identified the appropriate frequencies and signal processing methods to detect bubbles in liquids under both static and flowing conditions. These same methods were then successfully applied vis-à-vis a slip flowing through a pipeline using special sensors attached to the outside of the pipe.

A compact prototype detection unit was designed and produced by the SME electronics manufacturer Pulsar16 for use in practical trials to be carried out by CERAM at working ceramics factories. Under most conditions, the prototype detected air bubbles reliably. It was effective when used both on metal and plastic pipeline systems and, importantly, the new system was considerably more convenient than previous testing methods.

Dr Small says the new device can be fitted easily and quickly to existing pipeline systems. Attached to the outside of the existing pipes, it can immediately provide data about total air content and with further, more sophisticated data processing software it can give information on the size distribution of bubbles in the casting slip. During the field trials the system proved well-suited for use as a diagnostic tool. Air entrainment can be caused by a number of factors: too tight corners causing turbulence; poor or improper valve settings; improper process order, etc. In short - poor design or operating practices are to blame. One or more BUBBLE devices can be set up at different locations in a pipeline system so as to pinpoint weak spots where bubbles are formed. Monitoring could also be established on a semi-permanent basis and the system set to automatically signal an alarm when excessive air is present. Operation requires a minimum of disruption, maintenance and user intervention.

The new system was launched commercially at the Ceramitec exhibition in Munich in October of 2000. The main targets are ceramics manufacturers, as well as builders of new factories where project partners hope their system will quickly be taken on as standard equipment. The European ceramics industry as a whole stands to achieve substantial improvements in productivity, reductions in losses and consequent savings through the use of this system.

Qualceram in Ireland and Koninklijke Sphinx in Holland are end-user sanitaryware manufacturers; Bidasoa in Spain and Bridgewater Pottery in the UK are end-user tableware manufacturers; Pulsar16, also in the UK, is an electronics supply company; CERAM Research in the UK is an application research group; and the University of Southampton performed technical research.

As with many such projects, there were major challenges in holding the consortium together and ensuring that all objectives were met on time and within budget. As project co-ordinator, Dr Small says there were several occasions when for various reasons the project could have been abandoned. But strength and determination brought it to a very successful conclusion. Says Small, "We got there. We have a good product and all are happy."