Model 278 UGC Vibrating Densitometer0 pages

CHANDLER ENGINEERING

®

PROCESS INSTRUMENTS

Model 278 UGC Vibrating Densitometer
Vibrating Densitometer for Pipeline and Process Measurement
Features and Benefits
►t Continuous on-line density
measurement
►t No moving parts; accurate and
reliable
►t Provides input for mass flow
calculations
►t Small and compact
►t Excellent repeatability and longterm stability
►t Designed for use in Class I,
Division 1, Groups C and D
hazardous locations (model 278
CSA approved)
►t Measurements made at
operating conditions
►tt asily installed and maintained
E
►tt urable
D

from Ni-Span C, a nickel-ironchromium alloy with additions of
aluminum and titanium, for excellent
long-term stability under the most
difficult conditions. For corrosive
applications, other materials are
available.

Operation
The Vibrating Densitometer is
composed of two tubes and end
pieces forming a mechanical
resonant system. The tubes are
maintained in oscillation at resonant
frequency by an electronic amplifier
that uses a piezoelectric driver
and pickup elements in a feedback
arrangement. The Densitometer
is installed with scoops in such
a manner that a sample of the
fluid from the pipeline is diverted

through the two tubes — flowing
up through the first tube and down
through the second. The fluid,
therefore, becomes a part of the
vibrating elements, and the resonant
frequency (and also period) will vary
with the density of the fluid. The
relationship between density and
period of oscillation can be defined
with the following second order
equation:
Du = K0 + (K1 x T) + (K2 x T2)
Where: Du = Density, in gr/
cc, uncorrected for pressure or
temperature; and T = Period
(microseconds). K0, K1 and K2
are determined at calibration by
measuring the period of oscillation
with three liquids of known density
and solving three simultaneous
equations for the coefficients.

Description
One of the many parameters that
must be accurately measured for
product quality control, custody
transfer, process control, or liquid
interface detection purposes is
liquid density. For more than 25
years, the Chandler Densitometer
has been used by major pipelines
and other industries for reliable,
rugged and accurate fluid metering
(custody transfer), pipeline interface
detection, and as a blending and
process control tool. The frequency
output of the Chandler Vibrating
Densitometer is compatible with
most flow computers (consult factory
for details).

The Chandler
Densitometer has been
used by major pipelines
and other industries for
more than 25 years.

t The Vibrating Densitometers are
rugged and accurate and designed
to meet the most demanding
applications found in pipeline
and process measurement. The
vibrating element is manufactured

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