[TowerTalk] Water in Conduit...

[TexasRF--- via TowerTalk]

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 at 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 at contesting.com>  wrote:
>>
>> Hi Perry, any conduit will end up with water  inside unless it is
>> pressurized.
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