Richards wrote:
> Right, Rick.
>
> Many antenna manufacturers fail to adequately distinguish
> between inside and outside diameter. DX-Engineering sells
> a 43 foot monopole made of aluminum TUBING and it starts
> with a 2" OUTSIDE DIAMETER (OD) .... TUBE...
>
> But the instruction manual says to mount the tilt plate on a
> 2 " PIPE, and PIPE is measured by its INSIDE DIAMETER
> (ID) -- so if you tell them you are going to mount it on a 2 inch
PIPE IN NOT MEASURED BY INSIDE DIAMETER.
All so-called "2 inch iron pipe size" pipe has an OUTSIDE diameter
of 2.375 (2 3/8) inch. The inside diameter varies depending on
the schedule. For schedule 40, it is a little over 2 inches.
For schedule 80, it is a little under 2 inches. For thinwall
plastic sprinkler pipe, the ID is over 2 1/8 inch. The reason
for this scheme is so that all pipes use a common set of threads
and the fittings are interchangeable.
People using water pipe for a mast are likely using "1 1/2" inch
pipe, which is 1.9 inch OD, even though they may call it "2 inch"
pipe.
Conduit trade sizes have the same OD as pipe, except EMT,
which has its own unique set of dimensions.
Rick N6RK
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