MEASUREMENT & MONITORING
STATE-OF-THE-ART
KOBOLD
THE WORLD’S SMALLEST DUAL-TUBE
CORIOLIS MASS FLOW METER: HIGH
PRECISION MEASUREMENTS WITHIN 150 MM
Due to the weight influence of sensor coils,
for the measurement of very small flow-
rates it is common practice to use single
tube Coriolis flow meters. The sensor coils
of dual-tube Coriolis sensors are mounted
onto one of the two measuring tubes, thus
having, by very small tube diameters, a
significant weight influence on the tube on
which they are mounted.
Therefore, the influence of the sensor coils
on the measurement results increases by
decreasing tube diameter. For this reason
single tubes are often favoured for the
measurement of very small flow‑rates,
where the coils are mounted to the chassis
and not on the tube. However, with
the use of just one measuring tube the
influence of external interferences increases
dramatically. To reduce this sensitivity
and at the same time delivering accurate
measurements at very small flow rates,
Heinrichs Messtechnik has developed the
dual-tube Coriolis principle to a new level.
In this new state-of-the-art technologie,
the sensor coils are no longer mounted
onto the tubes, but rather between them,
thus freeing the measuring tubes from the
influence of the coils weight allowing for
extremly small tube diameters in dual-tube
design.
The result is the world’s smallest dual-
tube Coriolis Mass flow-meter: The high
Performance Coriolis (HPC). With an
installation length of just 150 mm it is
now possible to achieve high accuracy
measurements with deviations of just ± 0.1
percent. Furthermore, the sensor shows
insensitivity to temperatures of up to
180 °C, to pressures of up to 600 bar as well
as to strong vibrations.
“Market observations have revealed an
open gap in the measurement of small
flow rates”, explains Frank Schramm, the
managing director of Heinrichs Messtechnik
GmbH. The current problem is that the
state-of-the-art stipulates the use of
dual-tube technology, where the magnets
are mounted to one tube, the exciter and
sensor coils to the other. However, for very
small flow rates this principal has a decisive
limit. For example, where extremely small
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PECM Issue 42
Heinrichs Messtechnik GmbH developed the smallest dual-tubed-Coriolis-Mass-Flowmeter in
the world: The High Performance Coriolis (HPC). With an installation length of just 150 mm
high accuracy measurements are achieved with deviations of just ± 0.1 percent
flow rates demands a tube diameter of just
1 mm, the vibrating behavior of the coils
weight can influence the measurement
results significantly. “Therefore it is
common practice to use one tube systems
for these applications, in which the coils
are mounted to the chassis of the sensor.
This system has the decisive disadvantage
in that the second tube, which also serves
as a measurement reference, is omitted,
requiring that the sensor coils be mounted
on to the chassis of the enclosure making
the sensor more susceptible to vibrations
and other disturbances.
For this reason, Heinrichs Messtechnik
GmbH has set as its objective, the
development of a high precision, shock
resistant Coriolis Mass Flow Meter. Emerged
is the High Precision Coriolis – short HPC –
with its installation length of just 150 mm
the smallest Coriolis mass flow meter in
dual-tube design.
REDUCING DISTURBANCE
INFLUENCES BY POSITIONING
THE SENSOR COILS BETWEEN
THE MEASURING TUBES
“Due to the sensitivity single tube Coriolis
sensors, a costly mechanical decoupling
is often required, rendering them
inappropriate for many applications. Our
quest was therefore to find a means of
unifying a dual tube design with very small
diameter tubes”, explained Schramm. Since
the fundamental problem lies in the weight