Today's Message Index:
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1. 12:33 PM - Re: RVSouthEast-List Digest: 13 Msgs - 01/28/07 (Scott Keadle)
2. 02:35 PM - Re: Re: RVSouthEast-List Digest: 13 Msgs - 01/28/07 (bburril)
3. 04:21 PM - Re: RVSouthEast-List Digest: 13 Msgs - 01/28/07 (Scott Keadle)
4. 06:27 PM - Re: Re: RVSouthEast-List Digest: 13 Msgs - 01/28/07 (bburril)
Message 1
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| Subject: | RE: RVSouthEast-List Digest: 13 Msgs - 01/28/07 |
I read all these posts on the digest, so sorry for the delay, but I have to
add my two cents. Bournelli and Newton, notwithstanding (when we got to
railroad cars I was worried Max Planck had entered the fray), the most
notable thing in Steve's post was the instruction to disconnect the wires to
the transducer and reconnect them. I hate to agree with Boyd, but I think
it's either wires or, as James pointed out, an obstruction that was cleared.
Scott
________________________________ Message 13
____________________________________
Time: 07:48:19 PM PST US
From: "Ed Anderson" <eanderson@carolina.rr.com>
Subject: Re: bubbles and pressure was : RVSouthEast-List: Fuel Pressure
Fixed
I agree, Stormy, if you have a steady state condition. However, when
the system environment is not static but dynamic then you can indeed
have fluctuation states that cause the state in one part of the system
to be different than another part.
Consider two rail road cars separated by a untearable bag of air,each
car with a force measuring instrument (after all pressure is simply
force over an area, right?). Then back an engine into the first car at
some rate of speed. The first car will "feel" the impact essential
instantaneously over its entire length and the force measuring device on
the first car will register the force of the impact. However, at the
same instant the force measuring sensor on the second car will register
zero force. It will continue to register zero force until the pressure
inside the air bag has increased sufficiently ( due to the compression
forces) that the compressed air is able to transmit some force to the
second car. Yes, eventually, the second car will measure the same force
as the first car - but not instantaneous, there will be a delay. Now
repeated back up the engine and ram the cars again and again and you
have a rather chaotic and dynamic system with the air compressing,
collapsing, rebounding, etc.
Therefore, you can have two different sections of the liquid
(separated by bubble(s)) that see difference forces and therefore
pressures varying in a dynamic manner. In a real fuel line the
situation is considerably more dynamic than my example.
In a fuel line with multiple bubbles the situation can be complex. You
have a pump that may be creating bubbles through caviation, you will
have some amount of air bubble being re-absorbed back into the fluid,
you have bubbles being created by pressure drops through fittings,
temperature increases, etc. You may even have a leak that permits air
into the system. So depending on the level your are viewing it at -what
may appear to be a steady state system is its anything but a steady
state system.
Air in fluid lines is generally not a good thing - just how bad the
effect can - depends on a number of variables.
But, if you have had no problems - then I certainly wouldn't worry about
all those little bubbles {:>)
my 0.02 and I'm off to bed
Ed
----- Original Message -----
From: Bill Boyd
To: rvsoutheast-list@matronics.com
Sent: Sunday, January 28, 2007 9:28 PM
Subject: Re: bubbles and pressure was : RVSouthEast-List: Fuel
Pressure Fixed
Response delays I'll buy, Ed. In fact, I'll take water-hammer
dampeners for $50, please ;-)
There may be as many "states of gas that can exist in a liquid" as
there are ways to leave your lover, but they are all at the same
pressure if they're confined in the same hose - or I live in a parallel
universe (a possibility I will disregard for the sake of continuing to
fly with you fine friends ;-)
-Stormy
On 1/28/07, Ed Anderson <eanderson@carolina.rr.com> wrote:
I think you are correct, Cappy. There are several states of gas
that can exist in a liquid, some which cause worst effects than others,
but in any case, they all appear to affect pressure measurements in a
line to various degrees. Although, the attached refers to air in a
hydraulic system the effects are the same in a pressurized fuel line.
Note that bubbles can cause changes in head pressure as well as
erroneous measurements and response delays.
Ed
----- Original Message -----
From: Steve Glasgow
To: rvsoutheast-list@matronics.com
Sent: Sunday, January 28, 2007 8:27 AM
Subject: Re: RVSouthEast-List: Fuel Pressure Fixed
What about compressibility of a gas verses a liquid. Water pipes
have air trapped in them all the time to prevent hammer effect. The
pressure sender is up the line not down the line. Pressure is correct
at the engine, just not the pressure sender which is way above the
carburetor. You may be correct if the sender is plumbed at the
carburetor but mine isn't. All I know is it worked. No more
oscillating fuel pressure.
Stormy, are you giving us bad coordinates again?
Love Cappy
----- Original Message -----
From: Bill Boyd
To: rvsoutheast-list@matronics.com
Sent: Sunday, January 28, 2007 8:05 AM
Subject: Re: RVSouthEast-List: Fuel Pressure Fixed
<sportav8r@gmail.com>
Smokey,
I think the trapped air compresses until it reaches equilib. and
then
transmits all the pressure on down the line... in doing so it
will
tend to dampen any pulses (soften the water-hammer effect,
what-have-you) but I think all the pressure will show up at the
transducer. Enlighten me if I'm overlooking the obvious.
It sounds like Cappy might have fixed his gauge but broken some
law of
physics. Typical Cappy maneuver if you ask me. Today I shall
have to
see if he messed up Bernouli and Newton's, by seeing if my wing
still
generates enough lift to fly :-)
Cappy, I'd appreciate it if you wouldn't break or damage
physical laws
that the rest of us use every day, just to get your gauges
reading
correctly; that's very selfish and won't be tolerated.
-Stormy
On 1/28/07, Ron Schreck <ronschreck@alltel.net> wrote:
<ronschreck@alltel.net>
>
> Steve,
>
> Glad to hear you are back in the air. Actually, your problem
and
> solution makes perfect sense to me (Monday morning
quarterbacking,
> however). If your fuel and oil pressure sensors are mounted
high on the
> firewall, it only makes sense that any air trapped in the
lines will
> never bleed out (down hill) without some help. True, the
trapped air
> may transfer some measure of pressure, but being much more
compressible
> than a liquid it would certainly be a false reading. I think
your
> solution merits a mention on the RV list and perhaps a
suggestion that
> these sensors be mounted low on the firewall to avoid the
problem
> altogether. Nice work, Cappy!
>
> Smokey
>
> -----Original Message-----
> From: owner-rvsoutheast-list-server@matronics.com
> [mailto:owner-rvsoutheast-list-server@matronics.com] On Behalf
Of Steve
> Glasgow
> Sent: Saturday, January 27, 2007 5:13 PM
> To: SERV
> Subject: RVSouthEast-List: Fuel Pressure Fixed
>
>
> --> <willfly@carolina.rr.com>
>
> Turns out there was apparently air in the line to the sender.
Probably
> from
> lines being open on annual.
>
> I flew before doing the procedure below and the fuel pressure
was all
> over
> the place. From 4 to 9.5 psi.
>
> Anyway here is what to do to get the air out. Disconnect
wires from
> fuel
> sender. Loosen sender so it can be moved by hand. Keep sender
hand
> tight
> and turn on electric pump. Now loosen sender till fuel comes
out around
> the
> pipe fitting. Then tighten to stop the fuel from leaking.
Turn off
> electric pump, secure sender and hook up wires. Done. From
now on I
> will
> do this procedure whenever a fuel line is opened.
>
> I flew before doing this and the fuel pressure was all over
the place.
> >From
> 4 to 9.5 psi.
>
> Cappy
Message 2
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| Subject: | Re: RE: RVSouthEast-List Digest: 13 Msgs - 01/28/07 |
Well thats all it was,two cents worth.
----- Original Message -----
From: "Scott Keadle" <scott@keadle.com>
Sent: Monday, January 29, 2007 3:30 PM
Subject: RVSouthEast-List: RE: RVSouthEast-List Digest: 13 Msgs - 01/28/07
>
> I read all these posts on the digest, so sorry for the delay, but I have
> to
> add my two cents. Bournelli and Newton, notwithstanding (when we got to
> railroad cars I was worried Max Planck had entered the fray), the most
> notable thing in Steve's post was the instruction to disconnect the wires
> to
> the transducer and reconnect them. I hate to agree with Boyd, but I think
> it's either wires or, as James pointed out, an obstruction that was
> cleared.
>
> Scott
>
> ________________________________ Message 13
> ____________________________________
>
>
> Time: 07:48:19 PM PST US
> From: "Ed Anderson" <eanderson@carolina.rr.com>
> Subject: Re: bubbles and pressure was : RVSouthEast-List: Fuel Pressure
> Fixed
>
> I agree, Stormy, if you have a steady state condition. However, when
> the system environment is not static but dynamic then you can indeed
> have fluctuation states that cause the state in one part of the system
> to be different than another part.
>
> Consider two rail road cars separated by a untearable bag of air,each
> car with a force measuring instrument (after all pressure is simply
> force over an area, right?). Then back an engine into the first car at
> some rate of speed. The first car will "feel" the impact essential
> instantaneously over its entire length and the force measuring device on
> the first car will register the force of the impact. However, at the
> same instant the force measuring sensor on the second car will register
> zero force. It will continue to register zero force until the pressure
> inside the air bag has increased sufficiently ( due to the compression
> forces) that the compressed air is able to transmit some force to the
> second car. Yes, eventually, the second car will measure the same force
> as the first car - but not instantaneous, there will be a delay. Now
> repeated back up the engine and ram the cars again and again and you
> have a rather chaotic and dynamic system with the air compressing,
> collapsing, rebounding, etc.
>
> Therefore, you can have two different sections of the liquid
> (separated by bubble(s)) that see difference forces and therefore
> pressures varying in a dynamic manner. In a real fuel line the
> situation is considerably more dynamic than my example.
>
> In a fuel line with multiple bubbles the situation can be complex. You
> have a pump that may be creating bubbles through caviation, you will
> have some amount of air bubble being re-absorbed back into the fluid,
> you have bubbles being created by pressure drops through fittings,
> temperature increases, etc. You may even have a leak that permits air
> into the system. So depending on the level your are viewing it at -what
> may appear to be a steady state system is its anything but a steady
> state system.
>
> Air in fluid lines is generally not a good thing - just how bad the
> effect can - depends on a number of variables.
>
> But, if you have had no problems - then I certainly wouldn't worry about
> all those little bubbles {:>)
>
> my 0.02 and I'm off to bed
>
> Ed
> ----- Original Message -----
> From: Bill Boyd
> To: rvsoutheast-list@matronics.com
> Sent: Sunday, January 28, 2007 9:28 PM
> Subject: Re: bubbles and pressure was : RVSouthEast-List: Fuel
> Pressure Fixed
>
>
> Response delays I'll buy, Ed. In fact, I'll take water-hammer
> dampeners for $50, please ;-)
>
> There may be as many "states of gas that can exist in a liquid" as
> there are ways to leave your lover, but they are all at the same
> pressure if they're confined in the same hose - or I live in a parallel
> universe (a possibility I will disregard for the sake of continuing to
> fly with you fine friends ;-)
>
> -Stormy
>
>
> On 1/28/07, Ed Anderson <eanderson@carolina.rr.com> wrote:
> I think you are correct, Cappy. There are several states of gas
> that can exist in a liquid, some which cause worst effects than others,
> but in any case, they all appear to affect pressure measurements in a
> line to various degrees. Although, the attached refers to air in a
> hydraulic system the effects are the same in a pressurized fuel line.
> Note that bubbles can cause changes in head pressure as well as
> erroneous measurements and response delays.
>
> Ed
>
>
> ----- Original Message -----
> From: Steve Glasgow
> To: rvsoutheast-list@matronics.com
> Sent: Sunday, January 28, 2007 8:27 AM
> Subject: Re: RVSouthEast-List: Fuel Pressure Fixed
>
>
> What about compressibility of a gas verses a liquid. Water pipes
> have air trapped in them all the time to prevent hammer effect. The
> pressure sender is up the line not down the line. Pressure is correct
> at the engine, just not the pressure sender which is way above the
> carburetor. You may be correct if the sender is plumbed at the
> carburetor but mine isn't. All I know is it worked. No more
> oscillating fuel pressure.
>
> Stormy, are you giving us bad coordinates again?
>
> Love Cappy
> ----- Original Message -----
> From: Bill Boyd
> To: rvsoutheast-list@matronics.com
> Sent: Sunday, January 28, 2007 8:05 AM
> Subject: Re: RVSouthEast-List: Fuel Pressure Fixed
>
>
> <sportav8r@gmail.com>
>
> Smokey,
>
> I think the trapped air compresses until it reaches equilib. and
> then
> transmits all the pressure on down the line... in doing so it
> will
> tend to dampen any pulses (soften the water-hammer effect,
> what-have-you) but I think all the pressure will show up at the
> transducer. Enlighten me if I'm overlooking the obvious.
>
> It sounds like Cappy might have fixed his gauge but broken some
> law of
> physics. Typical Cappy maneuver if you ask me. Today I shall
> have to
> see if he messed up Bernouli and Newton's, by seeing if my wing
> still
> generates enough lift to fly :-)
>
> Cappy, I'd appreciate it if you wouldn't break or damage
> physical laws
> that the rest of us use every day, just to get your gauges
> reading
> correctly; that's very selfish and won't be tolerated.
>
> -Stormy
>
> On 1/28/07, Ron Schreck <ronschreck@alltel.net> wrote:
> <ronschreck@alltel.net>
> >
> > Steve,
> >
> > Glad to hear you are back in the air. Actually, your problem
> and
> > solution makes perfect sense to me (Monday morning
> quarterbacking,
> > however). If your fuel and oil pressure sensors are mounted
> high on the
> > firewall, it only makes sense that any air trapped in the
> lines will
> > never bleed out (down hill) without some help. True, the
> trapped air
> > may transfer some measure of pressure, but being much more
> compressible
> > than a liquid it would certainly be a false reading. I think
> your
> > solution merits a mention on the RV list and perhaps a
> suggestion that
> > these sensors be mounted low on the firewall to avoid the
> problem
> > altogether. Nice work, Cappy!
> >
> > Smokey
> >
> > -----Original Message-----
> > From: owner-rvsoutheast-list-server@matronics.com
> > [mailto:owner-rvsoutheast-list-server@matronics.com] On Behalf
> Of Steve
> > Glasgow
> > Sent: Saturday, January 27, 2007 5:13 PM
> > To: SERV
> > Subject: RVSouthEast-List: Fuel Pressure Fixed
> >
> >
> > --> <willfly@carolina.rr.com>
> >
> > Turns out there was apparently air in the line to the sender.
> Probably
> > from
> > lines being open on annual.
> >
> > I flew before doing the procedure below and the fuel pressure
> was all
> > over
> > the place. From 4 to 9.5 psi.
> >
> > Anyway here is what to do to get the air out. Disconnect
> wires from
> > fuel
> > sender. Loosen sender so it can be moved by hand. Keep sender
> hand
> > tight
> > and turn on electric pump. Now loosen sender till fuel comes
> out around
> > the
> > pipe fitting. Then tighten to stop the fuel from leaking.
> Turn off
> > electric pump, secure sender and hook up wires. Done. From
> now on I
> > will
> > do this procedure whenever a fuel line is opened.
> >
> > I flew before doing this and the fuel pressure was all over
> the place.
> > >From
> > 4 to 9.5 psi.
> >
> > Cappy
>
>
>
Message 3
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| Subject: | Re: RVSouthEast-List Digest: 13 Msgs - 01/28/07 |
Well Ben, between me and Ed, that's four cents. With another twenty one cents,
we could afford "short-time" with your girlfriend.
--------
Scott Keadle
14A, Lake Norman Airpark
N426AK RV-10, building
N180MP G202, flying
Read this topic online here:
http://forums.matronics.com/viewtopic.php?p=91441#91441
Message 4
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| Subject: | Re: RVSouthEast-List Digest: 13 Msgs - 01/28/07 |
Which one, she might be cheaper then that.
----- Original Message -----
From: "Scott Keadle" <Scott@Keadle.com>
Sent: Monday, January 29, 2007 7:21 PM
Subject: RVSouthEast-List: Re: RVSouthEast-List Digest: 13 Msgs - 01/28/07
>
> Well Ben, between me and Ed, that's four cents. With another twenty one
> cents, we could afford "short-time" with your girlfriend.
>
> --------
> Scott Keadle
> 14A, Lake Norman Airpark
> N426AK RV-10, building
> N180MP G202, flying
>
>
> Read this topic online here:
>
> http://forums.matronics.com/viewtopic.php?p=91441#91441
>
>
>
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