Flow measurement
ROUND UP
I
n 1932 engineers from Bopp & Reuther Messtechnik, based in
Speyer, Germany, invented the oval wheel meter. Based on the so
called positive displacement measuring principle, this technology
measures accurately volumes of liquid flow using two precise rotat-
ing oval rotors. Each rotor rotation allows a given volume of liquid
to pass through the meter.This volume can be measured using local
mechanical indicators; in that case the meter doesn’t need any power
supply to perform the measurement. Alternatively it is also possible
to detect the rotation of the rotors using electronic sensors and count
their pulses, each pulse being proportional to a given volume of flow
and providing the volume or flow rate on a local electronic indicator or
via 4-20 mA signals or electronic pulses to a remote flow computer. In
this case the electronic uses either a battery or external power supply.
Users appreciate positive displacement meters and especially oval
wheel meters because they are proven in rugged applications since
decades, and extremely reliable showing not only extremely high
accuracies down to 0,1% of measured value but also a high repeat-
ability and long term stability (no drift of zero or similar). Moreover
this measuring principle is insensitive to flow profile, allowing the
users to install suchmeter in extremely compact way.Vibrations, pres-
sure or temperature will not affect the quality of the measurement.
Recently Bopp & Reuther Messtechnik presented a new develop-
ment of its technology and introduced a so called energy harvesting
module. This module is at the same time a sensor able to detect
the rotation of the oval wheels and more or less a sort of ‘dynamo’
extracting directly in high efficient manner as much electrical energy
out of the rotation of the oval wheels without however impacting the
excellent metrological properties of the meters.This electrical energy
is employed to supply a local electronic indicator. Depending on the
application the life time of the battery can be only prolongedbut in
specific cases it is even possible to design a self-sustaining meter.
As an example a pilot project demonstrated successfully the fea-
sibility of controlling the plausibility of the fuel volumes out coming
of several fuel dispensers. In this application the local electronic
indicator is fitted with a GSM module transmitting the fuel balance
volumes periodically to a data center. Here the user is able to control
the plausibility of these data in order to detect fraud or vandalism at
the fuel stations. As another example a special set-up can be adapted
to already install oval-wheel meters in order to generate electrical
power locally.This power can supply a local electronic indicator or be
used in combination with a data transfer module, e.g. GSM. It is then
possible for the user to control remotely the data transmitted and their
plausibility. By this means the stocks or the transfer of products can
be remotely controlled. It is possible to detect faults like leakages in
pipeline systems or overload events in pumping stations.
These kinds of tailor made solutions are completing the broad and
reliable offer of Bopp & Reuther Messtechnik with new innovative
flow metering electronic products and help our customers to further
reduce their costs of ownership.
Enquiries:Tel. 011 257 6100 or email
T
he
Atrato
is the culmination of eight years research and develop-
ment in collaboration with the Department of Process & Engineer-
ing at Cranfield University. It can handle low flows from luminar
to turbulent and is largely immune from viscosity. It has excellent
turndown, repeatability and linearity and can monitor flow over a
range of 200:1. Accuracy is better than approximately 1,5%.
Utilising patented technology that enables it to operate with ex-
cellent accuracy over very wide flow ranges, across the whole span,
the Atrato range of inline flowmeters is a genuine breakthrough in
flowmeter technology. Its rugged, clean bore construction makes the
Atrato ideal for a whole range of low flow applications and its USB
port allows software connectivity at literally the touch of a button.
Its signal processing system permits flow measurement across the
whole Reynolds number range allowing both viscous and non-viscous
products to metered accurately, whilst signal discrimination identifies
anomalies in the flow and generates reports as required.The Atrato’s
time of flight measuring system measures both the upstream and
downstream flight times and half the difference is the velocity of
the fluid. Its patented system measures these time differences to an
accuracy of more than 200 picaseconds, indicative of its excellent
metering performance. As the pipe geometry is know the resulting
pulse output is accurate for the volume passed.This performance is
further enhanced by our primary signal to noise ratio which is typi-
cally 1000:1 and at times as high as 3000:1.
Enquiries: Email
K
obold Instrumentation, represented in SouthAfri-
ca by
Instrotech
- a Comtest Group company – has
launched the KFR line of acrylic body flowmeters of-
fering the perfect balance between low-cost, accuracy
and range availability. Bridging the microflow and
large flow ranges, this flowmeter can provide an ef-
fective solution to industrial applications, such as gas
analysis and water applications.The KFR operates on
proven suspended float system, ie the installation po-
sition is vertical and the flow is from bottom to top. It
has a one-piece acrylic body with PVC or metal fittings
for durability. Large lettering and extra hash marks
make the scale clearly visible and take the guesswork
out of reading flow. Further enhancing readability, the
low flowmeters offer an inherently stable float design,
while the larger flowmeters feature a float stabilisation
mechanism. In the larger flow ranges, the stabilisation
mechanism allows a smaller installation footprint at
a correspondingly lower price. Most units are offered
both with, or without needle valves. Accuracy, value,
low cost are three non-mutually exclusive attributes
which are made possible by Kobold KFR flowmeters.
Enquiries: Pieter Deysel.Tel. 011 462 1920 or email
.
Energy harvesting and oval wheel meters
Excellent flow accuracy
New low volume variable area flowmeters for liquids and gases
19
December ‘13
Electricity+Control
