ATEX approved Alarum for CSO Applications.
Hawker Electronics were approached by a well known
International Water Company who had a small problem.
They wanted to monitor levels in Combined Sewerage
Overflows or CSO's as they are better known, especially
low and high levels.
They had trialed floats for very low levels and found that the float
was too large for the application. They also found that at high
levels turbulence caused erratic movement of the float.
Hawker Electronics showed that their electrode system had no
moving parts to tangle up or wear out. Trials were conducted with
the 'Alarum' which is a compact electrode holder with an integral
electronic circuit. The circuit is very low voltage operating from
24 v DC with such low power requirements that it could run from
a solar panel or batteries. A 24v DC 12A/H battery will power
it for around 600 hours. The Alarum had originally been designed
for alarms in remote areas or in containment sumps and bunded
Following extensive trials two modifications were requested. The
electrodes needed to be more substantial for higher flows and the
unit needed to be ATEX approved for Intrinsically Safe applications
demanded by CSO's. The first requirement was straightforward.
The second one was more demanding but with Hawker's experience
in Intrinsic Safety and their background in sewage applications
ATEX approval was achieved in just over 3 months.