Hi Patrick, there is this thing called condensation that lets water
droplets form and collect over time. When buried, most of the conduit will be
at
a constant enough temperature that condensation can't happen.
But, the first few feet on both ends are above ground and can have enough
temperature drop from warm days to cool nights to condense some droplets of
water. With no way to drain, they will collect and only evaporation can
remove the collected water.
Seeing no evidence of water ingress does not mean that it does not happen
as it could have been there and has now evaporated.
In North Texas, the Summer and Fall are the primary times that condensation
happens. This is evidenced by the presence of dew in the mornings. If
there are dew drops on your patio table, you can bet there are also dew drops
in the ends of your conduit.
This is the same scenario that allows water ingress into Heliax cables with
a hollow center conductors. Air inside the center conductor condenses
water droplets that can leak by the center pin and collect inside the
connector
cavity. In this case you can seal the center pin with teflon plumbers tape
to keep the water inside the center conductor.
This is not an option with cables in a conduit so we have the various fixes
we are discussing here.
Seems there is no "perfect" solution.
73,
Gerald K5GW
In a message dated 3/5/2015 9:22:05 A.M. Pacific Standard Time,
patrick_g@windstream.net writes:
I wonder what keeps the water inside of PVC pipe when pressurized to 100
PSI plus with no leaks but lets water at a couple PSI, at most, get in
from the outside if not pressurized with compressed air on the inside.
Another one of the things that can make you go hmmmmmmmmmmmm.
Patrick NJ5G
On 3/5/2015 11:12 AM, Doug Smith wrote:
> Here’s a data point: I have used underground PVC conduit for many years
with no water ingress. There are two runs, about 100’ each. Both are 3”
PVC, chemically welded and plowed into the ground by a sprinkler company.
After 7 years, I pulled the cables out and they were dry as a bone.
>
> 73,
> Doug, W7KF
> http://www.w7kf.com <http://www.w7kf.com/>
>
>
>> On Mar 5, 2015, at 9:22 AM, TexasRF--- via TowerTalk
<towertalk@contesting.com> wrote:
>>
>> Hi Perry, any conduit will end up with water inside unless it is
>> pressurized.
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