Ron Karjian
It may be "deja vu all over again" with this year`s shortage of fluorinated ethylene propylene (fep), a compound used to insulate Category 5 utp plenum cable. But neither the past nor the present shortage can be blamed on El Niño. Properties that make fep desirable for use in Category 5 plenum cable include a low dissipation factor as well as low and stable dielectric constant across wide frequency and temperature ranges; low smoke characteristics; flame retardancy; good humidity stability; and suitability for thermoplastic-type wire extrusion.
After Category 5 utp cable won approval from the tia in 1991, demand from installers and distributors for the cable shot through the ceiling. Cable manufacturers could not keep pace with a demand that increased by as much as 50% in cable-feet per year from 1992 to 1995. And with the shortages came higher prices.
Installers and designers were forced to plan their installations further ahead than normal, and when appropriate, used nonplenum cable to get the job done. Bell Laboratories, which was designing high-performance local area network cables at the time, said it was "spending considerable time and resources looking at several different designs that expand the amount of cable footage with fewer materials, examining the use of alternative materials, or using different combinations of those materials." In the meantime, distributors were forced to sell to contractors and installers on a per-project basis only.
DuPont, the major supplier of Teflon (the trademark name for fep) products in the United States, wasn`t geared up to manufacture enough fep to fill the sudden increase in demand for cable of the early 1990s. DuPont had to increase production capacity by 25% per year and also expand its fluoropolymer capacity for co-polymer resins by 75%, committing about $150 million in capacity upgrades through 1997. Daiken America, which marketed fep under the name "Neoflon," was the only other supplier of fep at the time of the shortage. It was "out of inventory" and had to build a new plant to increase production of plenum-wire insulation materials.
"The Teflon shortage caused a significant backlash in the industry, which led to performance deficiencies of high- performance cabling by way of delay skew for mixed dielectric cable constructions," says John Siemon.
"The single biggest series of events in the cabling industry was and is the availability of fep for use in Category 5 plenum-rated products," adds Pete Lockhart, director of structured cabling technology at Anixter Inc. (Skokie, IL). "The previous shortage, coupled with the fast adoption of Category 5 utp cable, had caused rapid cable-design changes that were generally counterproductive to good electrical performance. The whole propagation-delay-skew issue came to a head in late 1995 and was one of the main factors that caused Anixter to rewrite its purchasing specifications."
The aftereffects of that 1995 shortage may have passed, but fep is again in short supply. And it remains to be seen whether the cabling industry will continue in a feast-or-famine cycle, or whether effective alternatives to fep will finally emerge.
