Advantages of PUR for Cable Jackets

19. December 2022

You can find more information on our web, so please take a look.

4 Min read

Contents

Written by Hermann Christen

Market Development Manager R&M

Fiber optic cable for outdoor use

Fiber optic networks are expanding more and more. They take future broadband supply everywhere. In cities and urban regions, FTTH networks can be quickly installed in roads and canals. Fiber optic cables with a PE sheath are generally well-protected here.

Today, there are more and more new or expanded fields of application outdoors, in which fiber optic cables are exposed to harsher ambient conditions without being additionally protected. Examples of these fields of application:

• Aerial deployment: Rural regions want to get broadband into homes using fiber optic aerial deployment and drop solutions. This is more cost-effective than underground cabling. However, aerial cables have to withstand constantly changing weather conditions.
• Event and sports organizers, broadcasting, and the military are increasingly relying on fiber optics. The cables must withstand changing mechanical loads such as transverse pressure, tension, and friction during laying.
• The industry is increasingly using pre-terminated fiber optic cables for chemically contaminated environments. In addition, there are other industrial applications in outdoor areas with a lot of dust and dirt, for example.

That is when the question arises as to which cable material is suitable. Companies are looking for a solution that stands up to all outdoor challenges in the long term. The answer is PUR.

Polyurethane, or PUR for short, is a highly developed, halogen-free thermoplastic elastomer. It is ideal for cable jackets.

Five advantages of PUR cables

PUR has five major advantages over the regularly used sheath materials polyethylene (PE), polyethylene with flame-retardant additive (LSOH), and PVC. PUR cables are:

• Mechanically stable. This means abrasion-resistant, impact-resistant, fatigue-resistant, tear-resistant, and cross-pressure-resistant; the soft PUR material acts as padding.
• The cables remain permanently movable even in low temperatures and freezing temperatures down to -50 °C.
• Oil, chemicals, UV radiation, etc. PUR is more resistant than standard materials for fiber optic cables.
• Weather-resistant. PUR cables are suitable for outdoor use in all climate zones, even when exposed to high levels of ozone, salt water, wind, or sunlight.
• And PUR cables hardly shrink or stretch when exposed to cold and heat, which means less stress for the internal fibers.

Of course, one disadvantage should also be mentioned here: PUR cables cost more than PE or LSOH cables. And always remember: The well-known standards and directives apply to PUR just as they do to any cable material. This applies to fire behavior, halogen-free behavior, and similar parameters.

Solutions from R&M

As an internationally active wire manufacturer with its own production in Europe, R&M offers market-driven PUR solutions. In our cable catalog, you will find twisted-pair patch cords and fiber-optic aerial drop cables with PUR sheathing.

In addition, the R&M cable catalog provides detailed information on the specifications and coding of the cable products in the «Explanations» section.

… and recommendations

For fixed installation cables, R&M recommends using standard cables and also giving them additional protection if necessary. For example, stable ducts, plastic or metal pipes, and reinforcements provide protection. PE and LSZH cables meet the requirements satisfactorily for most purposes in WAN or LAN cabling.

Companies should consider whether the advantages of the application justify the additional price. In some cases, it is particularly important that the cables are mechanically resilient and can withstand organic liquids over the long term. PUR cables are recommended here. Aerial drop cables with a PUR jacket are recommended for FTTH expansion with aerial deployment.

• As cable experts, we provide you with expert and immediate advice.
• For more information, please visit the R&M site for fiber optic cables.

Several factors come into play when selecting a cable. From the core right up to insulation, each wire is made of a number of components and materials that enable its correct functioning. The wrong cable materials can seriously affect the correct functioning of the whole application and cause major damages, often with costly consequences.

Fire-proof insulation

The simplest way to achieve flame retardancy is to add halogens to plastic. Only

a few additi

ves are required for this and they do not affect the mechanical

properties of the c

Howev

that they release toxic smoke gases in the event of a fire, which combined with

extinguishing water, can form corrosive vapours.

An alternative to halogens are HFFR plastics (Halogen Free Flame

Retardant) but they require to be 60 per cent of the compound which can

hinder the mechanical properties of the plastic. “Synergists” are a new

trend: these are materials which together provide a higher threshold of flame retardancy. For example, a synergist consisting of halogen-free aluminum trihydrate and silane compounds is a great option for fire retardancy. Aluminium trihydrate reacts with fire to form aluminium oxide and water, an endothermic reaction that takes heat from the fire. It also forms a crust of burnt material that serves as a protective layer.

Harsh environment? Use a protective jacket

Depending on the application, cables must be able to resist lubricating oils, grease

If you want to learn more, please visit our website FSW.

and cleaning agents. For mechanical engineering there are now special cables with

sheaths made of polyvinyl chloride or polyurethane (PVC). PVC is the industry standard

for most cables as it is easy to extrude and is resistant to a wide range of oils

and chemicals. However it can be cut easily which can cause potential damage to

some mechanical applications. PUR is harder to extrude and makes the

manufacturing process longer, however it is a better material in areas where mechanical

damage may arise. Downsides is that it is flamable and more expensive than PVC. The

cable types ÖLFLEX® 408P and ÖLFLEX® 409P , which have a PUR outer sheath and a

gusset-filling functional PVC layer, are an example of a compromise that combines the high resistance of PUR with the simple processing of PVC.

In the food industry resistance to microbes and fungi is key. Sheath materials made of special TPE, such as the ROBUST cables from LAPP, are perfect for F&B applications. Thanks to their smooth surface, they prevent the build up of microbes and are easy to clean. The secret of LAPP's special thermoplastic elastomer is a sophisticated mixture of additives that fills microscopic gaps in the material and remains bound in the plastic matrix even during intensive cleaning with a steam jet.

Stainless steel - yes, but...

Stainless steel is the material of choice when products need to withstand chemicals

or detergents, especially in the food industry. It does not rust and there is no coating

that could eventually break down. But here, too, there are differences. Hypochlorous

acid is particularly used in the food industry, which decomposes to hydrochloric acid

and kills organic substances. Common V2A stainless steel however is not resistant to

hypochlorous acid and therefore it is not recommended for the F&B sector. Instead,

LAPP recommends V4A which is overall a more resistant alloy. It is extremely hard

and can withstand harsh abrasion (i.e. hard brushes used for cleaning).

On the other hand, stainless steel is also very difficult to process. This is especially true for V4A. If left untreated, V4A is rough and causes high friction. LAPP subjects its V4A stainless steel products, such as the EHEDG-certified SKINTOP® HYGIENIC cable gland, to a special surface treatment that reduces surface roughness. This is crucial to ensure thorough and complete cleaning.

Stainless steel is not suitable for rectangular connectors because the hardness of the metal means that it cannot be processed efficiently. LAPP has therefore taken a different approach with the EPIC® ULTRA: the housing of the rectangular plug is made of nickel-plated die-cast zinc. This material is corrosion resistant and therefore suitable for a wide range of applications - from oil drilling platforms to food factories.

Rubber keeps it tight

Where metal meets metal - for example a plug connector meets a switch cabinet

- there is usually a seal. In terms of temperature and media resistance, the seal

must be as hard wearing as the other materials in the installation. One (almost)

all-rounder is fluorocarbon rubber (FCM). It is resistant to weathering, ageing and

ozone, as well as chemicals, and holds its own against the elements. If the ambient

conditions are moderate, ethylene-propylene-diene rubber (EPDM) is also a good

alternative. FCM has a small disadvantage - it is not suitable for very cold

environments below -20 degrees. Silicone is more suitable for cold rooms or other

freezing environments.

So how do you choose the best material for your application? Often there is no single answer that clearly indicates which material is best. But the right partner can offer knowledge and support through this process, helping you make the right choice.

Contact our experienced team via the enquiry form below to help find the best cabling solution for your requirements.

Contact us to discuss your requirements of pur cable material. Our experienced sales team can help you identify the options that best suit your needs.