[TowerTalk] Phillystran Tension Gage

[Ken Alker]

I'm new to this, but did a lot of research and found that the Loos PT2 
appears to be calibrated for wire with a breaking strength of 4545-5000 
lbs, while the Rohn 3/16EHS500 wire has a breaking strength of 3990 lbs.  I 
assume, based on specs on various types of wire rope found at 
<http://www.wcwr.com/catalog/webcat.pdf>, that the Loos PT2 is calibrated 
more for 1x19 Stainless Steel type 304 wire rope used for sailboat rigging 
(4700 lbs) rather than zinc coated 3/16EHS500 (3990 lbs).  Here is my math 
based upon the chart found on the Loos gauge (from the web site quoted by 
Tim, below):

 LBS   %  LBS/%
----  --  -----
 240   5  4800
 300   6  5000
 420   9  4666
 500  11  4545
 640  14  4571
 840  18  4666
1030  22  4681
1240  26  4769

In conclusion, perhaps one should pay more attention to the "LBS TENSION" 
portion of the Loos chart than the "% BREAK STRENGTH" if using the Loos for 
3/16" EHS (assuming it deflects in the same way that the sailboat wire rope 
deflects), or one may overtension their guys.  (Although, perhaps the error 
when tensioning to 10% of breaking strength when tensioning to 400lbs, or 
600lbs in the case of Phillstran, isn't big enough to worry about?)

Even then, however, I'm very curious as to why the Loos numbers are all 
over the map (4545-5000) rather than consistent at one breaking strength; 
it is not just rounding error since their "LBS TENSION" appears to be +-10 
lbs.

Ken, KA6KEN


--On Tuesday, July 13, 2021 12:09 AM -0400 Tim Duffy <k3lr at k3lr.com> wrote:

> The required steel leaders at the ground ends are in series with your
> Phillystan - no worries - so no problem for the Loos Gage.
>
> https://www.dxengineering.com/parts/loo-pt-2
>
> 73,
> Tim K3LR @ DX Engineering.com
>
> -----Original Message-----
> From: TowerTalk [mailto:towertalk-bounces at contesting.com] On Behalf Of
> John Keating
> Sent: Monday, July 12, 2021 11:53 PM
> To: towertalk at contesting.com; kb8nnu at yahoo.com
> Subject: Re: [TowerTalk] Phillystran Tension Gage
>
> Hi Dave,
>
> After searching far and wide to come to the conclusion there is none
> commercially available, I built my own tension gauge based on a suggestion
> from K6OK who did the engineering on my tower. It involved a 6' 2x4 with
> pulleys at each end and required calibrating the deflection under load of
> the phillystran in the center of the span between the pulleys using a pull
> gauge (I used a cheap fishing scale). You can sanity check the results
> with a bit of trigonometry.
>
>
>
> John
>
>
>
> On 7/12/2021 7:22 AM, Dave Eagle wrote:
>
>> Hello,
>
>> I recently put up a 40' Glen Martin tower with phillystran guys
>> (.22").?? I
> was looking for a way? to measure the tension on the Phillystran >to
> balance the install out.? I was originally thinking I could utilize the
> Loos PT-1 or PT-2 but the ranges don't match the manufacturers >specs.?
> The GM docs that I have call for 100-175 lbs.
>
>> Is there anything available to measure the force in that range that will
> take a .22" phillystran?
>
>> Thanks,
>
>> DaveKB8NNU
>
>
>
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