Conti's CO2 hose needs no stainless tubing

Hanover, Germany - Phoenix -now part of ContiTech - has developed a new type of CO₂ refrigerant hose that does not require the stainless steel tubing that was required previously.

The company has made the polymeric barrier layer on the inside of the hose much more flexible than the previous solutions, making tighter bending radii possible," says Mike Eismann, Head of Central Research & Development at ContiTech Fluid Technology. In addition, the elastomer hose with barrier layer demonstrates much better acoustic properties, presenting significant cost advantages in comparison to the corrugated tube hose solutions.

The hose has the proprietary barrier layer at the core, followed by an elastomer layer. These two form the main fluid barrier. This is followed by an extra-heavy duty aramid layer. This is followed by an outer sheath of EPDM for physical protection.

The hose can withstand up to 600 bar.

In a statement, Conti said, "In the low pressure range, the permeation rate of the barrier layer elastomer hose is 0.21 g per year, in the high pressure range 0.70 gram. Even if this emission of CO₂ is unproblematic from an ecological point of view, the automotive industry is currently demanding values under 1 g per year so that the function of the air conditioner systems is guaranteed during the maintenance intervals."

"In both areas, we are now already able to replace the corrugated tube hose with the barrier-layer elastomer hose," says Eismann. The only area where the newly developed product with its temperature resistance of up to 100°C does not yet represent an alternative is the hot gas sector, where temperatures exceeding 180°C must be withstood.

"The material development has been completed, now we just have to get the hose ready for volume production," explains Eismann. Now, the biggest challenge is the development of the necessary fittings, which must maintain a seal at pressures exceeding 140 bar. Refrigerants such as CO2 will be required by law in automotive air conditioners starting 2011. "By that time, it will be ready for volume productions," says Eismann.

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Press release from Conti