HANDLING of pressurised gas cylinders safely and efficiently for testing is an issue facing suppliers of the many industries that use oxygen, nitrogen, argon, hydrogen and carbon dioxide in their processes.
Inflatable Airstroke air spring actuators available in Australia from Air Springs Supply Pty Ltd are used across a broad spectrum of materials handling applications where pneumatic force needs to be applied evenly and gently across surfaces (some of which are irregular or curved).
These Airstrokes - available in capacities from a few dozen kilograms to more than 40,000kg - don't contain rigid rods or plungers, so they can flexibly tolerate off-centre loadings and bend through an arc without the complexity of a clevis.
Their lack of rigidity also means they do not impose high point loadings on a surface, which can damage it.
Even spread of force was an advantage recently when a manufacturer of pressure test equipment and gas boosters sought to simplify the pressure testing on its high-pressure gas cylinders.
The cylinders tested by Haskel Energy Systems in the UK had to undergo periodic pressure testing to ensure safety and to pinpoint areas of fatigue.
Testing of the large cylinders - up to 100L - requires standing them vertically in rows with the open end to the top. The top is sealed and pressurised with water to the test pressure, after which the cylinder is emptied.
Upending the heavy, water-filled cylinders could be cumbersome and dangerous, said Air Springs Supply engineer Chris Webb, who has had more than 25 years experience researching and implementing Airstroke applications worldwide to refine technologies suitable for Australasia.
"Haskels engineers devised a way to stand up as many as six cylinders side-by-side like soldiers, linked and stabilised by the pressure of a single Firestone air spring between each of them," he said. "They developed a mechanism using a single-convolution air spring that clamped the cylinders securely to they could be inverted and drained."
The cylinders are clamped around the centre of gravity of the filled cylinders, then pivoted with a rotary cylinder along the centre of gravity to upend them.
Each Model 116 air spring is sandwiched between two metal plates that fit snugly to the cylinders when inflated at up to 4bar (60psi). The two plates are also connected by coil springs that help collapse the air springs once the air pressure is released.
The compact single-convoluted Model 116 Airstrokes (in essence, highly engineered doughnut-shaped balloons) have a stroke of more than 7.5cm. This is considerably greater than the deflated Airstrokes' collapsed height of 5cm, a compactness that makes them easy to install into production lines and processes, including conveyor lines.
Each of the Model 116 air springs can provide more than 1,000kg of force at 5.5bar, though lesser force and pressure is required in the Haskel application.
Haskel Sales Director Peter Kaveney said the air springs provide the gentle but secure pressure needed to keep the cylinders secure without damaging them. The air springs provide a good controlled clamp force that does not put too much pressure on the cylinders, he said.
Chris Webb said the ability of air springs to provide even force across broad areas and to reliably tolerate side loadings has been widely employed in manufacturing and materials handling applications, including conveyors and loaders.
They are so good at distributing force evenly that they are used in vehicle stamping presses at Ford Australia to provide counter-pressure to huge hydraulic body parts stamping presses, so as to enhance the precise fit of parts produced by them.
Information about the full range of Airstroke actuators and Airmount isolators can be obtained through the new website of Air Springs Supply Pty Ltd, www.airsprings.com.au, which is one of Australia's most comprehensive guides to pneumatic actuation, isolation and suspension.