New Tru-Flex Internally Insulated, Zero-Leak Exhaust Bellows Readies Industry for 2013 Environmental Regulations

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Unique, Integrated, Internal Insulation Makes Design Significantly More Cost Effective and Practical than External Solutions

Ours is the first and only internally insulated exhaust bellows.

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Tru-Flex Metal Hose, an industry leader in innovative exhaust component and flexible metal exhaust de-coupler technology, announced that its new Internally Insulated, Zero-Leak, Torsional and Non-Torsional Bellows is being showcased at booth 224 at the 2011 SAE Commercial Vehicle Engineering Congress at Rosemont, Ill., Sep. 13 – 14, 2011. The product’s internal insulation approach is patent pending and provides OEMs with an intelligent, lower cost, engineered alternative to more primitive, exterior “blanket” methods that can actually damage exhaust components and compromise their service life.

2013 emission standards for on- and off-highway vehicles and equipment will not only require that exhaust systems be leak-free from the turbocharger through the treatment system, but also will place stringent new requirements on heat loss. The 2013 regulations will limit the amount of heat loss from the turbocharger to the inlet of the diesel particulate filter by an additional 10 degrees Fahrenheit. The current EPA regulations allow a temperature drop not to exceed 35 degrees Fahrenheit, whereas in 2013, heat-loss tolerances will be limited to 25 degrees Fahrenheit.

Before the introduction of the Tru-Flex Internally Insulated Bellows, design engineers had been relegated to the use of exterior insulation systems. External systems often take the form of bulky blanket-like wraps that use thick insulating material, structured around a metallic wire lattice. An insulating blanket’s wire mesh can cause wear points on the bellows and the insulating material constantly exposes the system to the corrosive effects of moisture and debris that can ultimately undermine the integrity of exhaust components.

“Ours is the first and only internally insulated exhaust bellows,” said Win Thomas, President of Tru-Flex Metal Hose, LLC. “This consolidated, leak-free, engineered system reduces OE acquisition cost on the front end and their exposure to warranty and replacement issues on the back end.”

The unique design of the Internally Insulated, Zero-Leak, Torsional Bellows also features a no-leak de-coupler that accommodates all four motions, including torsion. These bellows are particularly well suited for engine layouts that have exhaust outlets in parallel with the crankshaft, or that demonstrate torsional outputs that create more than two percent displacement at the site of the exhaust outlet.

The new Tru-Flex Internally Insulated, Zero-Leak, Torsional and Non-Torsional Bellows deliver unparalleled performance, reducing heat loss by up to 88 percent, as compared to unlined bellows. The dampening effect of the internal insulation provides the added benefit of a 70 percent noise reduction over non-insulated systems, greatly enhancing operator comfort. The Tru-Flex system also reduces static loss by a significant factor, thereby increasing vehicle engine performance and overall fuel efficiency.

From the inside out, this engineered solution is first comprised of a robust, flexible, interlocking interior liner, available in inside diameters ranging from 2.5 to 6 inches (63.5 to 152.4 millimeters). The interior liner is sleeved in a highly effective insulation material that is not exposed to external elements, or atmospheric conditions that plague external insulation systems. The internal insulation significantly enhances the fatigue life of the exterior torsional and non-torsional bellows by reducing their exposure to superheated exhaust gases.

“The internal insulation feature in our bellows is new, but the torsional feature has a proven, 10-year track record,” said Thomas. “This product is just another example of our focus on staying out ahead of marketplace regulations, so that we have products ready and waiting when the time is right for design engineers to incorporate them.”

The Tru-Flex Zero-Leak Torsional Lined and Insulated Bellows is the first product of its kind and has patents pending in both North America and Europe. Details, specifications and operation information for Tru-Flex’s entire range of exhaust components and flexible metal exhaust de-couplers are available at

High-resolution images relating to the Tru-Flex Internally Insulated, Zero-Leak, Torsional Bellows can be found here:

Video showing the torsional action of the Tru-Flex Internally Insulated, Zero-Leak, Torsional Bellows can be found here:

Editor’s Note:
About Tru-Flex Metal Hose, LLC
Tru-Flex Metal Hose, LLC. has been manufacturing metal hoses since 1962. Tru-Flex has taken its place as an industry leader by remaining committed to quality, customer service and on-time delivery, and by leveraging its significant engineering capabilities to create new and innovative exhaust component and flexible metal exhaust de-coupler designs. The company is committed to meeting customer needs across a wide variety of markets. The Tru-Flex engineered exhaust product line includes patented products such as: Zero-Leak Torsional Bellows, Zero-Leak Power Flex and TFL-SSS, standard stripwound interlock hoses. Tru-Flex is proud to serve a wide range of customers, including small businesses and large, global corporations, worldwide. Learn more at

Power Flex is a registered trademark of Tru-Flex Metal Hose, LLC.

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Rick Ashley
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