In a message dated 96-07-03 19:02:35 EDT, you write:
>Has anyone had any experiences with guy wires made of kevlar ?
>How are they compared to parafil rope ?
>I'll guess that they both are quite expensive.
Hi, Tom --
Phillystran is a guywire material that is made out of Kevlar aramid
fiber manufactured in the US. It is made in sizes from 2100 pound tensile
strength up to some really large sizes. The most common for amateur use is
HPTG4000I (equal to 3/16 inch EHS) and HPTG6700I (equal to 1/4 inch EHS). It
is covered with a PVC jacket which provides UV and abrasion resistance.
Special Phillystran Preform Big Grips are required for end terminations.
The two advantages of using it are 1) non-conductive and electrically
transparent for no antenna/guywire interaction and 2) its ease of
installation. It is somewhat more expensive than EHS guywire with guy grips
and ball insulators but takes a fraction of the time to cut and install. It
is approximately 20% more expensive than insulated EHS guywires.
Parafil rope is something I'm not specifically familiar with but sounds
like a typical synthetic laid rope material. If so, it is probably not UV
resistant and would require a larger size to provide the same working load.
For instance, 7/16 inch nylon rope would give you approximately the same
strength as 3/16 inch EHS (I'm sorry I don't have the metric equivalents). I
would only recommend rope used for guys in temporary installations ONLY - it
is not a reliable longterm guy material. In all cases, follow the tower
manufacturer's specifications. Failure to do so will result in,...well,
failure.
73, Steve K7LXC
TOWER TECH -- professional tower supplies and services for amateurs
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