REFLECTOR: Oil lines

["Al Gietzen" <alventures@email.msn.com>]

I sent this a week or so ago when Majordomo was upset with me for changing
access providers.  I think it got lost in hyperspace, so here it is again.
If yoiu've already seen it, immediately hit the "delete"

"Bob wrote:
>time to replace the 1/2 inch oil lines. However, I  wonder why because the
>entrance and exit holes from the by-pass valve have the same inside
diameter.
>To someone that does not know very much about fluid dynamics under
>pressure, it seem you can only move as much as will go thru the smallest
>openings, the ones in and out of the by-pass valve.
>
>Is the extra cooling provided buy the larger cooling surface of the 5/8
>inch tubing?  Can someone out there explain this?

The pressure drop in a fluid circuit is the sum of the pressure drops in
each part; elbows, orifices and lines.  The entrance and exit from the
by-pass maybe smaller, but they are also for a very short distance.  The
line is very, very long, and for viscous oil represents a large part of the
pressure drop around the loop.  Also, the flow area in the line increases as
the square of the diameter, so going from 1/2" to 5/8" will give you a 56%
increase in flow area and a corresponding decrease in pressure drop in the
line.

90 degree drilled elbows cause significant pressure also, so aviod them if
you can.  A 90 degree minimum radius bend in a tube will probably have less
than 1/4 the pressure drop of an elbow.

The outside surface area of the line is directly proportional to the
diameter, so if you're using the line as cooling surface, that area
increases by 25%.

I don't know; however, that the 5/8" line is required.  I do know that you
have to have the bypass valve setup for a high enough pressure to force
sufficient oil through the cooling loop.

Good luck."

Al Gietzen  RGE