FEATURE NEWS:
Waging war on water
When exposed to water, a deterioration in signal transmission in fibre optic or interrupted energy supply in a power cable can occur, causing high levels of inconvenience as well as repair costs. It is important to prevent water ingress into fibre optic, power and copper data/telecommunications wires and cables to ensure their safe and long-lasting operation. Cable wrapping tapes are becoming more advanced, replacing cumbersome alternative technologies. As a result, sales of water blocking tapes – widely used to prevent water ingress into and migration through cables – are now estimated to be worth approximately €17.76 million worldwide – and rising, particularly on the back of demand for Fibre to the Home (FTTH).
Blocking out water
Both fibre optic and power cables are highly susceptible to water infiltration – a common problem which can have costly implications for cable specifiers. When fibres are exposed to water, signal attenuation and degradation can occur, resulting in loss of data transmission. In underground power cables, water can travel up to 100 metres inside the cable due to capillary action. Identifying the problem can be difficult, resulting in interrupted energy supply and an expensive and labour intensive repair job.
Various technologies can be adopted to protect cables from water and moisture damage. These include the use of oil- and gel-filled cables, water blocking metallic sheaths and water-swellable tapes. Despite the continued use of all three methods, dry cable designs using water-swellable tapes are on the increase as they bring many advantages when used for fibre optic and power cabling systems, as highlighted below.
Efficient application: water-swellable tapes are easy, clean and speedy to apply during cable manufacture.
Flexibility: tapes can be adapted to work in a range of cable applications and provide additional benefits to water blocking. For example, tapes can incorporate both a non-woven layer for water blocking combined with a polyethylene terephthalate polyester (PETP) film for additional protection and cushioning. They can also be used to protect the underlying core from in process heating due to plastic sheath extrusion and provide a mechanical buffer or bedding layer. The possibilities for hybrid tape design are endless.
Eliminating migration: laminated water blocking tapes containing an impermeable PET film on one side are able to prevent grease or jelly within filled cable cores from migrating, as well as offering abrasion resistance.
Cost-effectiveness: capital investment and maintenance costs are lower compared with flooded or filled cables. In addition, cables using water-swellable tapes are lighter and smaller in diameter as less jacketing material is needed. This means the useful length of cable on a process reel/spool is longer and the maximum installed length of cable is greater, both resulting in cost savings to the cable manufacturer.
All wrapped up
When water enters a cable, water swellable tapes instantly form a water blocking gel, preventing further or more costly damage to the cable. Scapa Polymerics’ Megotape® water-swellable tapes range benefits from a super absorbent polymer (SAP). This is laminated between non-woven substrates to provide superior water-swellable protection. Following extensive research, the company has developed a portfolio of tapes which has excellent speed of response to water. Some tapes swell up to 50 times their original thickness within a minute.
The Megotape range is available in insulative, semi-conductive, laminated and marine versions depending on the cable application: insulative, semi-conductive and laminated. To complete the Megotape range of water blocking tapes, a marine tape incorporates salt water-swelling SAP which reacts on contact with sea water to prevent water penetration into undersea cables.
Innovating processes
Recent innovations in the market include two new ranges of high strength water swellable tapes, Megotape WSC 290 and Megotape WSD 290 for helical applications which, Scapa says, "fill a gap in the European and Asian markets where manufacturers demand high tensile strengths to sheath power cables. Other benefits include high resistance to elongation, durability and increased resistance to thermal deformation."
Scapa Polymerics is currently developing an improved manufacturing process to produce a thinner and smoother water-swellable tape. The tape’s reduced thickness will allow customers to benefit from higher yield package and reduce the overall size of the cable while its smoother texture will enable high speed manufacture.
Newer technologies incorporate water-swellable yarns in-between individual fibres; water-swellable tape is then wrapped around the whole cable before sheathing. This provides a much thinner cable construction compared with metallic water blocking screen.
Company: |
Scapa Polymerics |
Country: |
UK |
Fax: |
+44 161 320 6060 |
Email: |
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Website: |
www.scapapolymerics.com |