--- "Wm. Severin Thompson" <wsthompson@thicko.com>
wrote:
> Ron (Grasshopper...the Unlearned One) is no doubt
> sitting in his newly
> purchased racecar in his garage, making vroom vroom
> noises, with the wrong
> stick shift in his hand...
Grasshoppah back from walking on rice paper without
leaving mark...
This is all from memory, so no one bitch if I leave
out a few things. Pressure drop - the resistances
need to be considered in series. Glen is correct that
small fittings will control the resistance, but small
lines + small fittings is worse than large lines +
small fittings. To figure the difference, take
diameter 1 and raise it to the 4th power. Take
diameter 2, raise it to the 4th power it. Divide one
by the other - that's your difference.
Basically, the pressure drop is a defined by:
DeltaP = K * q
Looks a lot like V=I*R, right? and it is...
q is the dynamic pressure, aka velocity pressure, aka
"dynamic head" (easy, Flounder...). It is also .5 *
density * velocity squared/gravity. So the velocity
squared term dominates. What determines velocity?
V=w/(density * flow area). So as the area gets
smaller, the velocity gets higher at a given flow
rate. The area is a function of diameter squared, and
the q is a function of the velocity squared, hence the
4th power relationship above.
So what is "k"? It's a resistance factor, also a
function of geometry. For a hose, K=4fL/d, where 4f
is the friction factor, L is the length of
tubing/duct/etc, and d is the effective diameter of
the duct. So as d decreases, K increases, delta P
goes up. Again, small diameter is not good.
What about 4F? f is equal to (.046)/(Re^.2). And Re
is the Reynolds number, which is density X velocity X
diameter divided by viscosity. Again, small diameter
= high velocity, equals high Re, equals high f, equals
more pressure drop.
Enough of that, keep the restrictions small, the
pressure DROP will be low.
>
>
> ----- Original Message -----
> From: "Geoff Branch" <gjbranch@attbi.com>
> To: "Paul A. Asgeirsson"
> <Pasgeirsson@worldnet.att.net>;
> <JARplanner@aol.com>
> Cc: <Spridgets@autox.team.net>
> Sent: Tuesday, September 03, 2002 7:19 AM
> Subject: Re: Oil Cooler Hose Connections
>
>
> > Now, I have been thinking about this. The
> pressure of a system has
> nothing to
> > do with the size of a system. It has to do with
> the SMALLEST restriction
> within
=====
Ron Soave
1960 Bugeye
1958-ish Bugeye Racecar
1970 Midget
1996 Labrador Retriever
2002 F-150 tow vehicle
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