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[TowerTalk] Water in Conduit - How to prevent it

To: TOWERTALK@contesting.com
Subject: [TowerTalk] Water in Conduit - How to prevent it
From: Cqtestk4xs@aol.com
Date: Thu, 28 Feb 2013 11:00:41 -0500 (EST)
List-post: <towertalk@contesting.com">mailto:towertalk@contesting.com>
An ounce of prevention...a pound of cure.
 
At my new station I have over 1000 feet of buried conduit.  Solution  to 
the moisture.  Drill SMALL holes at the bottom every 20 feet or  so...maybe a 
1/4 inch and then place fiberglass screen patches over them.   If you are 
lucky enough to have runs going uphill or downhill or across a dip in  your 
property, you need only drill a hole or two at the lowest point to have the  
water drain out.
 
It works for me because I'm lucky enough to have sugar sand which drains  
quickly and doesn't accumulate water.  If you are going across a clay pan  or 
muck, my method will not work and you'll get water coming into the  conduit.
 
Bill K4XS/KH7XS
 
 
In a message dated 2/28/2013 3:38:36 P.M. Coordinated Universal Time,  
patrick_g@windstream.net writes:

Lots of  opinions and no consensus.  Typical.

I didn't have nary a drop of  water in my 3 inch conduit 6 months ago but I 
will check again because of  all the folks who think all buried conduits 
have 
water. I allow as to how  it is conceivable water is getting in there by 
whatever means. I do have  dried shop air available at both ends of my 
conduit so I suppose a  "calibrated leak" to put just a few cubic feet of 
dry 
air per day into the  run would totally remove any concerns for 
condensation. 
If all air  entering the conduit is really dry air there should never be 
any  
condensation in the conduit.  In one of my previous conduit runs to  the 
barn, I ran a small flexible plastic tube Rated for 200 PSI to a  
repurposed 
35 gal air compressor tank from a portable compressor with a  dead motor. 
This gives me air in the barn for tires etc.  It  recharges slowly but I'm 
not trying to power impact tools so no big  deal.  It could provide a 
little 
air to the coax conduit to keep it  under a slight positive pressure and 
dry. 
At the other (house) end of the  conduit I can install a small flexible 
plastic tube with a check valve  in-line.  This tube can be run to a 
convenient location and there  immersed in a clear water container 
(repurposed peanut butter jar. )   At a glance you can tell if there is an 
occasional bubble coming from air  exiting the conduit.  Any leakage of air 
through wires or coax  shields or loose jackets would be of dry air getting 
out not damp air  getting in. Problem solved. (If there is one.)

Total system cost in  time and materials?   Maybe as much as as a dollar in 
materials  (but more likely from scraps and such on hand) and maybe 15 
minutes to  drill the two holes and put in the tubes, gluing them in place. 
This time  estimate includes making the calibrated leak (small scrap 
petcock 
almost  shut off. If my cost estimates are totally bogus it will still be 
under $2  and 30 min.

An alternative would be a periodically replaced silica gel  pack desiccant. 
I use these for other purposes so have them on hand and  periodically 
recharge them in the oven.

Patrick AF5CK  

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