[SBE] Nitrogen

[Fluker, Steve (CXR-Orlando)]

I know there's controversy about the topic of dry air vs. nitrogen, but
from my experience, nitrogen is far better than dry air.  Dry air still
contains oxygen which will oxidize the copper.  I had two rigid lines on
adjacent towers in Orlando.  Once installed in 1979 which was evacuated
and pressurized with dry nitrogen it's entire life.  The second line was
installed in 1985 and due to some leaks in the antenna system, it had
been pressurized with a dehydrator.   In 1994 I made a change in the
1979 antenna and when I pulled the line apart, it looked the same as it
did the day it arrived off of the truck.  Never had any problems with
it.  We were just moving the antenna to a different location on the
tower.

Two years later (1996) we were having line burn-outs on the 1985 line.
Upon pulling the line apart the center conductors had oxidized and had
seized the watchband springs on the bullets causing some of the bullets
to fail.  We ended up replacing the inners and bullets.  It was
determined that the dry air from the dehydrator was the culprit.  I have
heard the issues with the Teflon bullets and nitrogen, but in my 30
years in radio I have yet to see this failure occur.  I have seen this
oxidation results on several lines now.  

 

Just my two cents.

 

Steve

 

From: sbe-bounces at sbe.org [mailto:sbe-bounces at sbe.org] On Behalf Of
Humphrey, Richard A
Sent: Thursday, May 07, 2009 11:41 AM
To: sbe at sbe.org
Subject: Re: [SBE] Nitrogen

 

There is a restaurant near one of my towers which gets CO2 for the soda
machine delivered in liquid form.  They have a cryogenic tank and gas
generator next to the road.  So if a pizza place can do this with CO2,
there should be off the shelf hardware available for storing liquid N2
and turning it into gas as needed that would work for transmitter
engineers.  The semiconductor industry goes through a lot of nitrogen
and other gasses.  This is how they do it.  But it's probably cheaper
just to plug in a dehydrator and use dry air.

Richard Humphrey

KMAX/KOVR-TV

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