Be a smooth operator
May 1st 2008

For compressed air pipework to be energy efficient coated aluminium pipe and engineering it needs a smooth bore. But it must also be quick to install and versatile. Tim McManan-Smith met up with Malcolm Crossley, managing director of Legris to discuss the Transair pipework system

If a compressed air system is to work at maximum efficiency, it stands to reason that the pipework needs to be in good order. Not only must it be devoid of leaks, it must allow compressed air to flow through the pipe smoothly, so avoiding turbulence and a subsequent pressure drop. Galvanised steel is the most popular pipework material purely through the sheer time it has been in use. But it is susceptible to corrosion and the rough interior surface that it creates can cause a significant pressure drop throughout the system that becomes worse with age.

Nowadays, anyone choosing compressed air pipework will want the best of all worlds; energy efficiency, high robustness and versatility in both installation and operation When Legris moved into compressed air pipework, optimum energy efficiency was on its mind – perceptive given that it was developed in the early to mid 1990s.

The most convenient pipework that helped to reduce the pressure drop associated with rust in conventional galvanised steel pipework was either plastic or aluminium. Plastic, however, can suffer from degradation through UV light, while high pressures can deform the pipework. Not being as solid as metal, plastic can bow and requires more brackets to install and support the ring main throughout the building. Malcolm Crossley believes lightweight aluminiumto be the ideal product for maximum flow, but only if the connectors do not intrude into the pipework to cause turbulence.

In 1996 Legris launched its rapid-fit Transair range, a system of powder- coated aluminium pipe and engineering grade polymer connectors. "Aluminium will not rust and is strong," he adds. "At the time it was launched it also had major advantages over plastic, not least the extensive downtime waiting for plastic to cure. Crucially, of course, glueing also prevents adaptability of the system." Legris' Transair flow calculator allows the appropriate pipe size to be selected for the job, from a range now extending to six sizes of pipe diameter from 16.5mm to 101mm. To achieve similar flow characteristics to Transair pipework, galvanised steel would have to be considerably wider and, of course, heavier.

The flow characteristics through Transair smooth bore aluminium pipework are crucial in helping to reduce the pressure loss through the system.

Each metre of pipe and each take-off to a component such as an air tool will cause a reduction in pressure. "For maximum system efficiency, Transair connectors do not intrude into the pipework to cause turbulence," says Crossley, "nor do they cause scratching on the outside of the pipe which can cause a leak at each connection." An energy calculator soon to be released by Legris will enable system designers to determine the precise savings to be made by using Transair in preference to other systems.

Crossley adds "Energy efficiency is now one of the key topics when we talk to specifiers of compressed air systems. Most understand the need to assess lifetime costs rather than just look at the initial capital expenditure.The message is getting through, but it needs to happen more quickly.

"Energy today has become enough of a cost centre to justify ripping out a galvanised system and putting in Transair.

The problem with a galvanised system is that you are not aware that it is failing and that you are wasting a large amount of energy".

For larger installations, Transair qualifies for interest free loans through the Carbon Trust's energy efficiency scheme.

Legris has its origins as a connection manufacturer dating back to the mid 19th century. The company invented the concept of the push-in pneumatic fitting in 1969, extending the range massively over the years to incorporate value-added benefits such as function fittings, miniature fittings for extremely small circuitry and manufacture in a range of materials to suit particular operating conditions.

It was from this full flow, push fit technology that the Transair pipework system was developed. Crossley explains: "Many pneumatic push fit connectors such as elbows may be 6mm at either end but can be reduced by as much as 25% in the middle. That causes pressure loss. Legris makes its connectors in the same diameter 6mm throughout the component to ensure that the flow is not restricted." That concept has been carried through to the Transair pipework system, where the flow through joins, branches and take-off points is completely unrestricted.

Installation has also been simplified to ensure the correct level of torque with every connection. Over tightening could cause cross-threading to interfere with the integrity of the connection and create leaks. Air will similarly escape if the connection is under tightened. With Transair, two arrows are simply aligned on the component to confirm that a leak-free connection has been made.

Further developments within Transair have seen a stainless steel range of pipework for use in applications such as the food industry where aggressive chemicals can be used, such as those in the washdown process. It is also a suitable carrier for process water, the second largest user of pipework within a factory environment after compressed air.

To aid the end user, Legris' network of Transair distributors is able provide system design, installation and commissioning. The system can then be extended or modifed easily by the end user according to changing requirements.

All Transair pipework and components are interchangeable, completely reuseable and guaranteed for 10 years.

The Transair pipework system

Transair is a full-flow, corrosion resistant pipework system available in both powder coated aluminium and stainless steel.

Assembly is through rapidfit, leakproof connectors, with no threads or dyes as for galvanised pipework and no need for glueing, as with plastic.

It will not rust like a galvanised system and will not crack like plastic.

Lightweight, for ease of installation, the Transair system is available in six sizes from 16.5mm to 101mm, with a wide range of components and accessories to allow systems to be tailored precisely to building and installation requirements.

All Transair fittings are interchangeable and reuseable, with powder-coated aluminium pipework suitable for compressed air, inert gas and vacuum, and stainless steel for applications such as process water.

All Transair components are guaranteed for 10 years.

Technical data Fluids: compressed air, vacuum, inert gases (nitrogen, argon).

For other fluids, please consult Legris.

Working pressure: from 13 mbar (0.19 PSI) to 16 bar (232 PSI) Working temperature: -20°C to +60°C (-4°F to 140°F) Safety: resistant to mechanical shocks and fire (all Transair components are nonflammable, with no propagation of flame).

Material used: engineering grade polymer (high resistance) plated brass stainless steel powder coated aluminium nitrile seals for aluminium EPDM / FKM seals for stainless 100% recyclable materials Storage temperature: from -40°C to +80°C (-40°F to 176°F) Resistant to compressor oils (mineral and synthetic)

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