Air Springs deploys its ultimate stealth fighters against NVH

Both silent and deadly to disruption – Firestone Airmount™ isolators, right, are the ultimate answer to noise, harshness and vibration

Isolators that so effective they have been used to exclude noise, vibration and harshness (NVH) from delicate instrumentation and sonar systems development are now being adopted in Australasia as a solution to increasing industrial, commercial and infrastructure NVH challenges

The Firestone Airmounts® from Air Springs Supply Pty Ltd have been used for applications as diverse as protecting building occupants and their electronic equipment from any disruption created by HVAC and emergency generating plant above them, through to suspending for more than 15 years a towering sonar test tank containing nearly 500 tonnes of water.

These ultimate pneumatic isolators – which typically achieve isolation efficiencies of more than 99 per cent – are also suitable for protecting building plant and facilities against NVH created by passing rail and road traffic, says Air Springs Supply National Sales and Marketing Manager Mr James Maslin.

Air Springs Supply is Australia’s national distributor of Firestone Airmount isolators and complementary solid Marsh Mellow® springs, which are used internationally in response to the demands imposed by expanding commercial building and infrastructure as well as workplace health and safety issues.

“In many cases they can virtually eliminate the noise, vibration and harshness (NVH) to which staff are subjected by heavy industrial equipment, such as vibrating screens, stamping tools, conveyors and rowdy process equipment suspended on clattering metal springs. As urban expansion and infrastructure development brings more infrastructure and engineering projects closer together, there is also a rising demand for isolators that can provide the uptime performance in protecting against ambient NVH sources, including passing rail and road traffic,” said Mr Maslin.

Airmounts deliver a range of very high isolation efficiencies across a very broad spectrum of needs, typically achieving isolation efficiencies of more than 99 per cent. Importantly, they achieve this extreme performance with reliability across a wide weight range. Their uses can extend from suspension of a 30kg computerised control panel, for example, to total suspension of the entire tonnage of common industrial plant such as motors, crushers and vibrating screen conveyors.

Super-silent Airmounts – either permanently sealed or fed by standard industrial compressor equipment – range from palm-sized to nearly a metre across, individually supporting weights extending from a few dozen kilograms up to more than 40,000kg. They are available in single, double and triple-convoluted types as well as rolling sleeve models in Australia’s leading range of such technology, a comprehensive range of which is housed in Air Springs Supply’s recently expanded headquarters in Sydney. They are distributed nationally by a supply and technical advice network built up over more than 40 years.

HVAC Airmount Airsprings Sonor
HVAC equipment (left) suspended on the black doughnut-shaped Airmounts, left. At right Andrew Cameron Managing Director of Air Springs Supply Pty Ltd, is dwarfed by air springs used by a huge sonar testing tank.

Engineered from tough fabric-reinforced rubber, Airmounts are identical in construction to the Airride® air springs used in the suspensions of heavy trucks seen every day on Australian roads and the ubiquitous Airstrike actuators used in applications such as industrial metal stamping presses and conveyors.

“The great virtues of Airmounts are simplicity, durability and sustained high performance,” says Mr Maslin. “According to our records, not one of the sonar testing air bags ever needed to be replaced. There was no wear, no unexpected leakage or maintenance – beyond the need to keep the air levels at the correct level, in much the same way you do with your car tyres.”

Either permanently inflated or adjusted by standard factory 7 bar (100 psi) compressed air, the Airmounts can be used in industrial and commercial applications as diverse as suspending tanks, pressure vessels and liquid containers in which delicate processes are undertaken, through to suspension of process control technology including computer and production automation equipment.

They can also be used to isolate the source of the NVH, suspending compressors, vibrating screens, bin hoppers, packers, blowers and stamping equipment that pass disruptive impacts into the area surrounding them.

Containing no internal moving parts to break or wear, Airmount isolators range upwards in size from the tiny palm-sized 1M1A model, which features a 35mm stroke, minimum (collapsed) height of fewer than 50mm and isolation efficiency of 97.8 per cent at 1500 cycles a minute. At the other end of the scale, huge triple- convoluted Model 348-3 isolators, measuring a metre in diameter, can support nearly 40,000kg and achieve isolation efficiencies of 99.3 per cent.

Air Springs Supply’s Headquarters
Air Springs Supply’s exanded national headquarters, from which it supplies its national service network
with high levels of stocking of product, range and security of supply .

The enormously strong Airmounts have been used to suspend four 16-tonne 2000kV diesel emergency generators only metres above the heads of top-level executives working in the highest floors of a Sydney CBD high rise. Big generators can produce up to 140dB in a confined space, when they are being tested, so the Airmounts had to produce a level of just 35-40dB in the floor immediately below, which is as quiet as a library.

“Using Airmounts to achieve outstanding isolation of building plant ranging from generators to swimming pools is almost as simple as it is possible to be – In essence, Airmounts provide a layer of air in a hugely durable heavy-duty balloon,” says Mr Maslin.

Marsh Mellow isolators
Marsh Mellow isolators, left, provide another low-maintenance answer to NVH

Firestone’s fabric-reinforced solid rubber Marshmellow isolators provide another low maintenance alternative for quiet isolation of machinery vibration and for general shock absorption throughout industry. Marsh Mellows are constructed of a solid rubber core with a hollow centre and several plies of fabric-reinforced rubber as an outer cover.
The plies provide the springs with stability as well as a consistent cylindrical shape. give consistent performance regardless of changing loads, while offering high lateral stability and compact size.
The low natural frequencies of Marsh Mellow springs mean they provide excellent isolation of forced frequencies in the range of 800-1200 cycles per minute (13-20 Hz),

Marsh Mellow springs are quiet in operation, unlike steel springs which readily transmit high frequency structural noise and often suffer from coil chatter. A failing coil spring may crack, causing fragments of the coil to damage equipment, resulting in expensive downtime.

“Their high load capability means fewer springs may be needed in an application, resulting in less overall cost,” said Mr Maslin, adding that Marsh Mellow spring elements may be modified to meet customers’ specific load and performance requirements.

ISO Certification

Air Springs Supply Pty Ltd has enhanced its commitment to national and global standards of quality assurance by gaining ISO 9001: 2008 Quality Management Systems – Requirements certification.

The company places a high priority on continuously reinforcing its customers’ confidence in doing business with an organisation that can consistently meet or exceed their needs on time.

ISO 9001 certification is invaluable to customers in demonstrating that the organisation involved can consistently provide products or services that meet the requirements of customers and of any applicable regulations relating to them. ISO 9001 benefits to customers include assurance of global standards of consistency, quality and supply of products for which Air springs is exclusive national distributor, including Firestone air springs – the world’s No 1 brand for heavy vehicle suspensions.