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.