Excellent question. I wondered about that myself when I installed my
Phillystran guys.
Seems to me if the cable is properly tensioned, there won't be a lot of
flexing at the end of the grips, so there won't be much chance the grips
will unravel. I would imagine the primary issue would be ice forming on the
cables, then sliding down and slamming into the end of the grip. Rohn sells
metal sleeves with their EHS grips that you tap over the ends of the grip to
guard against this. I put them on the upper ends of my EHS leaders, which
are now out of reach, but have yet to get around to putting them on the
bottom end of the leaders, where it would matter the most. While the metal
sleeves make sense, I would think nylon cable ties wouldn't do much to keep
a Phillystran grip end together if a chunk of ice slammed into it. I think
the tie would just slip down the grip. I wonder if ice is less likely to
form on Phillystran than EHS. Does anyone know?
The nylon cable ties appear to be made of UV-resistant material, so they'll
probably last longer than regular ties, but not forever.
However, I question whether the ties provide any real protection from the
grip unraveling. Though I pulled the ties as tight as I could, I had
problems with them slipping off when I transported the cables from my garage
to the tower site. Just normal flexing of the grip and cable during
transport caused this. I slipped the ties back in place. Like I said, if
there's enough force from falling ice to unravel the end of the grip, I
think the tie will just slip back away from the end. BTW, half my
Phillystran grips are at the interface between the Phillystran and EHS
leaders, so I can't reach them to substitute hose clamps. Those are the
grips that might need protection from falling ice -- the ends of the grips
attached to the tower face down, where ice can't slam into them.
Hose clamps would probably be more likely to stay in place than plastic
ties, but I'd be concerned about the clamp distorting the strands of the
grip, or worse, the Phillystran. Also, you don't want the sharp grip ends to
penetrate the delicate Phillystran jacket. It might be difficult to tighten
the clamo enough to hold the grip ends together but not cause problems with
the cable. I have a feeling this is why Preform doesn't supply metal sleeves
with their Phillystran grips: pushing the metal sleeve onto the end of the
grip could cause the strands to damage the cable. Same might happen with
hose clamps.
Bottom line, I would use the ties and not hose clamps. Hose clamps are not
specified by the manufacturer, and there's may be a good reason for this.
Also, it would violate the 'LXC prime directive: always follow the
manufacturer's instructions.
73, Dick WC1M
> -----Original Message-----
> From: Scott Dickson, W5WZ [mailto:W5WZ@arrl.net]
> Sent: Saturday, August 30, 2008 1:42 PM
> To: towertalk@contesting.com
> Subject: [TowerTalk] Phillystran and preformed grips
>
> Phillystran instructions indicate placing a single nylon 'zip tie' one
> inch
> from the ends of the short leg of the grip.
>
>
>
> Should I worry about the longevity of the nylon zip tie when exposed
> to the
> weather?
>
>
>
> Would a better solution be to use a small stainless steel hose clamp,
> or at
> the very least a cable clamp?
>
>
>
> --Scott, W5WZ
>
>
>
>
>
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