On Tue, 26 Aug 2003 22:55:54 +0000, Peggie Hall wrote:

Lloyd Sumpter wrote:
Not trying to justify my decision, but...a "1 inch" hose barb is actually
about 3/4" ID,

The flaw in your logic, darlin', is that fitting measurements are ALWAYS
OD, because it's the OD that has to fit into the ID of hoses. So when
specs call for 3/4", that means a 3/4" hose is what should be used...and
when they call for 1", a 1" hose should be used. The difference between
the ID and OD of the fitting is already taken into account. When you use
a smaller diameter hose, you are reducing the volume it can carry by the
percentage bomar's math indicates.


And the flaw in YOUR logic, darlin', is that I'm not using logic, I'm
measuring. The smallest ID that my sewage has to go through is 3/4"
(measured). This would also be true if I used a 1" thruhull, although the
LENGTH of the 3/4" restriction would be 2" rather than 7", which is what
is is now.

Most pressure drop in a restriction such as this occurs AT the reduction.
True, there's more pressure drop per ft in a smaller hose/pipe (fluid
travelling faster), but not significant compared to the dP at the
restriction itself (which is why we measure flow by measuring dP across a
restrictor-plate).

Now, I DO agree with you that 1" hose should be used on a 1" fitting,
3/4" hose on a 3/4" fitting, etc. - I HATE adapters! This is one reason I
want to go 1" rather than 1.5" - eliminates the adapter (I'll still need
an adapter to put my 1" hose on my 1.5" thruhull...)

Lloyd