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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