Flexible transport connections

Jon Lawson

Cengiz Citlak explores how, as a multi-functional component, hoses play an essential role in machine and plant engineering 

Hose applications are just as varied as the media they transport: highly temperature- resistant and extremely elastic cooling hoses prevent, for instance, X-ray equipment or processors from overheating.

Flexible hoses help make energy from the sun and geothermal power usable.

Extremely sturdy and flexible hoses keep automatic cutting machines or welders supplied with oxygen, fluxing agent or fuel gas.

Compressed air hoses as well as cleaning, water and delivery hoses are indispensable for structural, underground and mining engineering, as well as shipbuilding.

And in the chemical and pharmaceutical industry, special hoses are used, which ensure that aggressive and toxic media can also be transported safely.

To make the operation and production processes as smooth and efficient as possible for the user, hoses by ContiTech are constantly being developed. This results in innovative products such as the Dampf Trix 6000 Oil, which solves the conflict between the objectives of having oil resistance whilst also having a higher level of stability with regard to steam temperature, all within one flexible rubber product.

The oil-resistant outer layer is a particularly impressive feature of the Dampf Trix 6000 Oil.

Some other steam hoses often fail quite quickly due to external oil contamination.

The temperature-resistant inner layer made from high quality EPDM allows the hose to transport pure, saturated steam of up to 210°C at 18 bar, and even 220°C at 23 bar for shorter periods of time.

The hose fulfils all the test requirements of the German Industrial Standards DIN EN ISO 6134 - 2B and its smart design makes it a reliable and safe piece of equipment – even under the most challenging of conditions. It is suitable for use in the chemical and petro-chemical industry, in refineries, in the building industry and in numerous other industrial applications.

Tailor-made solutions for individual applications

In close collaboration with industry and research establishments, tailor-made product solutions are also  developed and produced for very specific application requirements.

The most recent example is a pressure equalisation hose that ContiTech developed for a new kind of underwater pump storage facility, which has been undergoing testing by the Fraunhofer Institute for Wind Energy and Energy System Technology (IWES) from Kassel, Germany, since November 2016 in Lake Constance, Europe’s largest reservoir of drinking water.

The biggest challenge in developing the hose was handling the water depth of 100m, which corresponds to an external pressure of around 10 bar. To ensure that the hose can be used in these difficult conditions it was designed with safety factor 3 for an external pressure of 30 bar. An additional steel helix in the hose wall gives it the necessary mechanical stability.

Lake Constance supplies around 4.5 million people with drinking water. Therefore the layers of the hose fulfil the requirements of the German Drinking Water Ordinance and the directives of the US Food and Drug Administration (FDA). This ensures that it will not cause any changes to the taste or smell of the water.

Adapting to operating conditions

To ensure that hoses function safely and reliably in the long term, the material and design must be matched precisely to the application conditions and the medium. From a selection of over 20 standard rubbers,

ContiTech develops specific elastomer mixtures that, for each respective application, perfectly match the required parameters such as resistance to temperature, UV and ozone, as well as pressure, robustness or flexibility.

And using sophisticated process technology, other features can be achieved, including precise wall thicknesses and optimum layer distribution. In addition, the choice of pressure-bearing component and reinforcement material affect the characteristics of a hose. 

Choice of differing fibres

Depending on the field of application, natural fibres can be used such as cotton, man-made fibres made from natural and synthetic polymers, as well as from non- organic raw materials or metals such as steel and copper.

Other aspects that affect a hose’s resistance to pressure, flexibility and dimensional stability include the number, design and geometry of the pressure-bearing layers. n

Cengiz Citlak is a technical consultant for industrial hose solutions at ContiTech

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