Level measurement solution relieves the pressure

From its mill in Heywood, Union Papertech supplies long-fibred, speciality filter papers to the international tea and coffee markets. The mill has an annual capacity of more than 6000t from two manufacturing libes that operate around the clock. It uses a number of pressure transmitters to monitor level in different parts of its process. In the past measuring level in the ‘pool box’, an open tank containing a mix of water and fibre, had proved problematic.

The instruments supplied by one of Endress+Hauser’s competitors continuously failed, much to the frustration of Union Papertech’s instrumentation engineer Keith Hopkinson. He explains: "The actual measurement isn’t that critical in this instance but what we do need is repeatability. Week after week we need to know that the transmitter is still reading the same level. The old ones weren’t even lasting six weeks. Production used to complain about it all the time.”

This instrument failure meant Hopkinson had to spend a large proportion of the company’s planned downtime trying to fix the problem. "I can’t work on it while the machine’s running so I had to wait for the machine to shut. I’d take the transmitter off, put it on the bench and test it, but there seemed to be nothing wrong. So I’d replace it and it would fail again. It was very frustrating, especially because the location of the transmitter makes it difficult to access.”

One of Endress+Hauser’s field sales engineers identified the cause of the problem on his first visit to the mill in 2011. He realised that the mill’s hot and humid environment was creating condensation that was entering the sensor and causing the drift. The solution was to replace several of the old transmitters with Deltapilot MFMB50 hydrostatic level transmitters. The measuring sensor in the Deltapilot is the Contite cell, which has been specially designed for plants with high levels of condensation. The ‘condensate tight’ Contite cell is hermetically sealed against the outside world, guaranteeing long life, stability and reproducibility in these challenging applications. Particularly designed for use in hygienic applications in the food and beverage industry, where CIP or SIP cleaning causes extreme temperature shock, the FMB50 has also proved suitable for use in any environment where condensation is formed.