Specifying cable protection to protect uptime
05 November 2019
Loss of power or data can be catastrophic for industrial plants, affecting both operational efficiency and safety. It is therefore critical to specify cable protection correctly to ensure uninterrupted performance.
However, there are many variables to consider, such as the choice of material, new or retrofitted options or even whether to opt for bespoke-designed cable protection. Flexible conduit manufacturer, Flexicon, explores the options available to ensure the specification suits the application.
Metal, nylon or composite conduit?
One of the first areas to consider is whether to opt for non-metallic (nylon), metallic or composite flexible conduit.
Before the development of engineered plastics, conduits and conduit fittings were made of metal. As plastics developed, they were used as sheathings to provide increased flexibility, plus improved water and corrosion resistance.
With the development of high-performance engineering polymers, all-plastic conduits were developed together with injection-moulded conduit fittings, with nylon polyamide (PA) being one of the most important materials now available.
With no exposed metallic content, non-metallic conduits do not rust or corrode thus maintaining performance and appearance over time. They are often quicker to install than metallic options as they are easier and faster to cut. Non-metallic fittings will typically be one piece and simply push on and twist to secure.
Where fatigue life or impact resistance is important, installers should consider nylon polyamide (PA) corrugated flexible conduits, which can offer high impact strength and recovery if crushed combined with excellent temperature performance.
Polypropylene and PVC conduits are available but their suitability is limited, with both of these systems being inferior to nylon polyamide (PA) when it comes to temperature range fire performance, resistance to solvents and abrasion resistance.
For installations subject to increased UV exposure, it is important to consider that ultraviolet (UV) radiation will naturally degrade any plastic materials. Failure could result in materials cracking, an increase in brittleness, reduced flexibility and lower impact strength.
Metallic and composite systems
Metallic systems are ideal for applications that require a very high compression or pull-off strength, or where there is the need to protect cables from exposure in hazardous environments. These systems typically have a higher level of crush resistance, high mechanical strength and can provide excellent EMC screening properties.
Composite products, such as plastic sheathing on metal conduits, metal over-braiding or metal threads on plastic fittings can also offer the ideal combination of light weight and high strength.
In existing applications, retrofitting cable protection has, traditionally, been a more complex task, with the installer required to pull existing cabling through the open end of a conduit system.
Conduit system manufacturers are therefore developing enhanced retrofit options to make it easier and quicker to install cable protection. Flexicon, for example, offers its FPADS range of divisible corrugated conduits. Manufactured from two nylon (PA6) interlocking slit corrugated conduits, the construction allows existing cabling to be inserted laterally via a slit opening. The two open conduits then interlock to form a protected IP40 system around the cables.
This effectively means that the customer can wrap a flexible conduit around the cables retrospectively with minimal disruption.
Bespoke-designed cable protection
For more complex application requirements, operators should speak to their supplier to discuss bespoke options.
These could include conduit supplied in non-standard or pre-cut lengths, in larger or smaller diameters or with different thread termination or fitting options. Additionally, more complex requirements, such as altering performance characteristics to meet a certain temperature requirement, compression strength or abrasion resistance or to achieve a greater fatigue life may also be considered.
Flexicon offers a design prototype service which allows customers to see new cable protection concepts, before investing in a full system solution. The service also includes bespoke testing and the preparation of customer samples for field trial and analysis.