[AT] Pressure drop?

[charlie hill]

Well that is kind of the same thing George.  Turbulence is introduced in a 
pipe by the "boundary layer" along the edge of the pipe if I remember right. 
The fluid/gas tends to "stick" to the pipe a bit.  That is assuming the flow 
was smooth going into the pipe to begin with.  I guess it wouldn't be from a 
compressor.

Charlie
----- Original Message ----- 
From: "George Willer" <gwill at gwill.net>
To: "'Antique tractor email discussion group'" 
<at at lists.antique-tractor.com>
Sent: Wednesday, January 30, 2008 9:58 AM
Subject: Re: [AT] Pressure drop?


> Charlie,
>
> I don't mind plunging in because I'm not hindered by advanced formal
> education beyond high school where I graduated nearly 56 years ago.  I've
> been trying to learn ever since.
>
> There is a flow issue with electricity but it doesn't compare directly to
> turbulence.  It's dependent on frequency and is called skin effect.  The
> higher the frequency the greater the tendency for the flow to be nearer 
> the
> outside (skin).
>
> George
>
>> -----Original Message-----
>> From: at-bounces at lists.antique-tractor.com [mailto:at-
>> bounces at lists.antique-tractor.com] On Behalf Of charlie hill
>> Sent: Wednesday, January 30, 2008 8:57 AM
>> To: Antique tractor email discussion group
>> Subject: Re: [AT] Pressure drop?
>>
>> I hate to get into this because I don't remember much about the little 
>> bit
>> I
>> used to know on this subject BUT.  There are a couple more variables that
>> need consideration.  One is the capacity of Farmers compressor.  If it is
>> marginal (say it only puts out 10 CFM) I think you can expect a larger
>> pressure drop than the charts might indicate because the compressor won't
>> be
>> able to keep up against the head.
>> The other is the issue of laminar vs turbulent flow.  Obviously in this
>> case
>> with 10 CFM flowing through a 1/2 inch line we are talking about 
>> turbulent
>> flow and that's probably what the charts are derived for.  I don't think
>> there is a flow type issue in electricity and now I'm really talking 
>> about
>> something I don't know anything about so I'll shut up.  Not trying to
>> start
>> an argument.  Just food for discussion.
>>
>> Charlie
>> ----- Original Message -----
>> From: "Dudley Rupert" <drupert at premier1.net>
>> To: "Antique tractor email discussion group" <at at lists.antique-
>> tractor.com>
>> Sent: Wednesday, January 30, 2008 12:50 AM
>> Subject: Re: [AT] Pressure drop?
>>
>>
>> > The following site contains a table that will answer the question
>> > (assuming
>> > the table is correct) -
>> >
>> > http://www.engineeringtoolbox.com/compressed-air-pressure-loss-
>> d_1014.html
>> >
>> > For example, it looks like for a 1/2" pipe with 10 SCFM of air flowing
>> > through it @100PSI the drop is 0.4 psi for every 100 feet of pipe.
>> >
>> > Like Dean said in a post a few minutes ago electricity and airflow
>> behave
>> > a
>> > lot alike.  Voltage drop is the easier to calculate however.  For
>> example,
>> > if you double the amount current through a wire you simply double the
>> > voltage drop between the ends of the wire (Ohms Law).  From the table
>> > above,
>> > however, it looks like air pressure drop in a pipe is more complicated
>> to
>> > compute; that is, it cannot be computed by a simple (linear) expression
>> of
>> > a
>> > couple of variables ... maybe with some regression analysis and fancy
>> > curve
>> > fitting one could come with a polynomial for computing air pressure
>> drop.
>> >
>> > Dudley
>> > Snohomish, Washington
>> >
>> >
>> > -----Original Message-----
>> > From: at-bounces at lists.antique-tractor.com
>> > [mailto:at-bounces at lists.antique-tractor.com]On Behalf Of
>> > rlgoss at insightbb.com
>> > Sent: Tuesday, January 29, 2008 7:16 PM
>> > To: Antique tractor email discussion group
>> > Subject: Re: [AT] Pressure drop?
>> >
>> > It's going to depend on the flow rate, Farmer.  If it's just a
>> pressurized
>> > line, there is no pressure drop.  But if you want it to deliver 9 CFM 
>> > at
>> > 90
>> > PSI, you may have trouble.  I don't have the formula with me for doing
>> the
>> > calculation, but it shouldn't be difficult to find.  Try searching for
>> > "line
>> > loss."
>> >
>> > Larry
>> >
>> >
>> > ----- Original Message -----
>> > From: Francis Robinson <robinson at svs.net>
>> > Date: Tuesday, January 29, 2008 20:57
>> > Subject: [AT] Pressure drop?
>> > To: Antique tractor email discussion group <at at lists.antique-
>> tractor.com>
>> >
>> >> OK, who knows compressed air pressure drop off of the top of
>> >> your head?
>> >> :-)
>> >> I am going to run a compressed air line from one shop to the
>> >> other. It
>> >> will run inside of an underground conduit in 1/2" PEX tubing. It
>> >> will
>> >> basically have one fitting (full 1/2") at each end of the run.
>> >> The run will
>> >> be 250' long with no fittings at all in the line itself. If I
>> >> have 125 PSI
>> >> at one end what kind of drop can I expect at the other end? What
>> >> would it
>> >> be at 800'?
>> >> BTW, PEX is rated and recommended for compressed air. I was
>> >> reading the
>> >> print on the pipe today and for water what I have on hand at the
>> >> moment is
>> >> rated at 100 PSI at 180 degrees F. It will not get hard and
>> >> brittle and it
>> >> will not shatter on impact. It is cross linked polyethylene and
>> >> is not
>> >> affected by oil.
>> >> I am really in love with this stuff for water plumbing.
>> >>
>> >>
>> >>
>> >>
>> >>
>> >> --
>> >> "farmer"
>> >>
>> >>
>> >> Francis Robinson
>> >> Central Indiana, USA
>> >> Robinson at svs.net
>> >> _______________________________________________
>> >> AT mailing list
>> >> http://www.antique-tractor.com/mailman/listinfo/at
>> >>
>> >
>> > _______________________________________________
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>> >
>> > _______________________________________________
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>> > http://www.antique-tractor.com/mailman/listinfo/at
>> >
>> >
>> > --
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>> > Checked by AVG Free Edition
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>
>
> _______________________________________________
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> http://www.antique-tractor.com/mailman/listinfo/at
>
>
> -- 
> No virus found in this incoming message.
> Checked by AVG Free Edition.
> Version: 7.5.516 / Virus Database: 269.19.11/1242 - Release Date: 
> 1/24/2008 8:32 PM
>
>