A bespoke pump maker is using ultrasound waves to efficiently model drive torque and thus contain development costs to within predictable limits
Charles Austen Pumps has recently upgraded test facilities with
surface acoustic wave (Saw) equipment from Sensor Technology.
Charles Austen Pumps manufactures pumps individually designed to
meet specific customer requirements that cannot be satisfied by
Over the three generations that this family
firm has been operating it has continually honed its skills at
accurately predicting development costs and working within
budgets, and has become adept at using advanced techniques such
as Saw analysis.
Much of its work comes down to optimising drive
dynamics to produce the desired characteristics, be it a smooth
flow in a critical medical situation, ultra low noise for pumps
in home and office installations, or the guaranteed extra long
life of pumps in inaccessible locations.
The cyclic nature
typical in many pumps' operation tends to induce torsional
oscillations in the drive shaft, which can have a significant
adverse effect on performance if unchecked, and this is where
much of Charles Austen Pumps's development effort is
focussed, as technical manager Brian Glover explains: "We
have recently built a new test station based on Torqsense, Sensor
Technology's Saw sensor, and it is proving its worth time
and time again.
Many years ago we used a simple torque arm and
scales when developing prototype, then we moved on to slip ring
technologies which were expensive and difficult to use because
they induced a frictional load of their own.
based on surface acoustic waves began to emerge about ten years
ago and we embraced these with considerable success." Saw
provides non-contact monitoring of instantaneous rotary torque,
allowing accurate modelling of the load changes.
Pumps built its own test stand and it served them well for many
"The state of the Saw art has now moved onto a higher
plane, so last year we decided to tap into Sensor
Technology's expertise and develop a new cutting edge test
They supplied us with a Torqsense unit and helped with
designing and building the rig." In essence a Torqsense is a
frequency dependent strain gauge operating at ultrasound
It consists of a transducer mounted on the shaft,
which monitors variations in resonance frequency of a drive shaft
as the torsional load varies and transmits a radio frequency
signal to an adjacent pick up.
Torqsense embraces all the
advantages of Saw technology, including a broader signal
bandwidth than other analogue based technologies and elimination
of electronic interference.
As Charles Austen Pumps found, it
often also proves far lower cost, simpler to use, is more
reliable and has a wider operating than contact alternatives.
Glover sums up: "Our reputation is based entirely on the
quality of our engineering, and our business on the ability to
accurately forecast development cost for each job.
Technology has helped us build a new facility that makes our
drive engineering accurate, predictable and reliable, or put
another way we are moving from a black art to an exact