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290 Series transmitters measure density as a function of differential pressure.
Each unit has two pressure sensitive diaphragms, each of which are located at
a known elevation in the tank. Under normal operation both diaphragms will be
submerged, and since the distance between them is fixed, any variation in the
pressure differential between them must be a function of the liquid density.
Within the sensor construction the diaphragms are hydraulically linked, the
lower diaphragm is "rated" to suit the density span whilst the upper
is compliant and provides a pressure transfer, via the hydraulic fill, to the
rear of the rated diaphragm. Actual displacement of the lower diaphragm is measured
using the proven LVDT principle. An amplifier module receives the LVDT's output
signal and conditions it to provide a 4 to 20 mA output over the required span.
For convenience this amplifier may be sited up to 100
Meters away from the sensor.
Our unrivalled experience in the design and application of pressure sensitive
diaphragms and a versatile approach to unit construction, ensures optimum performance
on all applications. Examples of previous successes include duties as diverse
as Beer fermentation vessels, where very small changes in density must be resolved
and hygienic construction is needed, and Drilling Mud storage vessels where
mechanical protection and rugged construction are essential.
Units can be manufactured to suit either external flanged, threaded, or hygienic
fittings, or as a completely submersible unit suitable for pole suspension or
clamping in place.
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