How much does the length of a vacuum hose affect the vacuuming suction?

Steve

On 2013-04-02, Steve B wrote:
How much does the length of a vacuum hose affect the vacuuming suction?


The longer is the hose, the thinner, and the greater the flow, the
more is the deleterious effect. It is the same as a hose offering
resistance to any other kind of flow.

i

On Mon, 1 Apr 2013 19:41:45 -0700, "Steve B" wrote:

How much does the length of a vacuum hose affect the vacuuming suction?

Steve

Virtually no effect on suction - may reduce flow somewhat. My central
vac pulls the same at the unit in the basement as it does on the
second floor about 15 feet up, using the same 25 foot hose.

don't forget the roughness inside. Is it a flat wall, or one
that creates turbulence. The wall must stand up to any pressure and not
collapse.
Martin

On 4/1/2013 9:46 PM, Ignoramus6646 wrote:
On 2013-04-02, Steve B wrote:
How much does the length of a vacuum hose affect the vacuuming suction?


The longer is the hose, the thinner, and the greater the flow, the
more is the deleterious effect. It is the same as a hose offering
resistance to any other kind of flow.

i

wrote in message
...
On Mon, 1 Apr 2013 19:41:45 -0700, "Steve B" wrote:

How much does the length of a vacuum hose affect the vacuuming suction?

Steve

Virtually no effect on suction - may reduce flow somewhat. My central
vac pulls the same at the unit in the basement as it does on the
second floor about 15 feet up, using the same 25 foot hose.

We have a Vacuflow 960--twin motors, with the unit capable of handling
18,000 square feet of building.

Length of the tubing most assuredly makes a difference. The vacuum cleaner
is located in the shop, with tubing extended (underground) to the
house--with the longest runs likely near 100'. There's an obvious
difference of performance in the house as opposed to in the shop. 2"
inside diameter pipe, if you have a question on size.

The rules of physics dictate that there will be losses.

Harold

"Ed Huntress" wrote in message
...
On Tue, 02 Apr 2013 05:32:10 GMT, "Harold & Susan Vordos"
wrote:


wrote in message
. ..
On Mon, 1 Apr 2013 19:41:45 -0700, "Steve B" wrote:

How much does the length of a vacuum hose affect the vacuuming suction?

Steve

Virtually no effect on suction - may reduce flow somewhat. My central
vac pulls the same at the unit in the basement as it does on the
second floor about 15 feet up, using the same 25 foot hose.

We have a Vacuflow 960--twin motors, with the unit capable of handling
18,000 square feet of building.

Length of the tubing most assuredly makes a difference. The vacuum
cleaner
is located in the shop, with tubing extended (underground) to the
house--with the longest runs likely near 100'. There's an obvious
difference of performance in the house as opposed to in the shop. 2"
inside diameter pipe, if you have a question on size.

The rules of physics dictate that there will be losses.

Harold

What Clare is saying, I believe, is that the length of the hose makes
no difference in the value of suction -- if there is no airflow
through the hose. If you hook up a vacuum pump to, say, a bell jar or
to a perfectly sealed vacuum-cure rig for composites, it doesn't
matter how long the hose is. The vacuum will be the same.

What reduces the vacuum is the drag experienced by airflow through the
hose. Longer hoses will measure the same vacuum at their ends, no
matter how long the hose, if there is no flow. But if there is flow,
the more there is, and the greater the inherent drag in the hose, the
lower will be the measured vacuum at the end.

Rules of physics.

--
Ed Huntress

Pretty much what I implied, although not so eloquently. In reality, the
longer the hose/pipe/conveyance medium, the lower will be the performance as
you move away from the vacuum. Friction is ever present. It's the same
with air lines.

The greater the volume that is being moved, the better the performance, thus
the two motors on the unit we have. Smaller units all have single motors.


Harold
Harold

On Tue, 02 Apr 2013 01:38:59 -0400, Ed Huntress wrote:
On Tue, 02 Apr 2013 05:32:10 GMT, "Harold & Susan Vordos"
wrote:


wrote in message
. ..
On Mon, 1 Apr 2013 19:41:45 -0700, "Steve B" wrote:

How much does the length of a vacuum hose affect the vacuuming suction?

Steve

Virtually no effect on suction - may reduce flow somewhat. My central
vac pulls the same at the unit in the basement as it does on the
second floor about 15 feet up, using the same 25 foot hose.

We have a Vacuflow 960--twin motors, with the unit capable of handling
18,000 square feet of building.

Length of the tubing most assuredly makes a difference. The vacuum cleaner
is located in the shop, with tubing extended (underground) to the
house--with the longest runs likely near 100'. There's an obvious
difference of performance in the house as opposed to in the shop. 2"
inside diameter pipe, if you have a question on size.

The rules of physics dictate that there will be losses.

Harold

What Clare is saying, I believe, is that the length of the hose
makes no difference in the value of suction -- if there is no
airflow through the hose. If you hook up a vacuum pump to, say, a
bell jar or to a perfectly sealed vacuum-cure rig for composites, it
doesn't matter how long the hose is. The vacuum will be the same.

What reduces the vacuum is the drag experienced by airflow through
the hose. Longer hoses will measure the same vacuum at their ends,
no matter how long the hose, if there is no flow. But if there is
flow, the more there is, and the greater the inherent drag in the
hose, the lower will be the measured vacuum at the end.

Rules of physics.

So... the implication is that "performance" here implies "time", much
like charging a capacitor. Hooking a capacitor across a battery with
voltage "V" will eventually charge the capacitor to "V"; putting a
resistor in series with the capacitor won't affect the final potential
across the capacitor: it will still eventually reach V. However, it
may take longer... perhaps a _lot_ longer. grin!

Makes sense: If I have a "vacuum-formed plastic object" production
line, I probably care whether it takes minutes, hours, or days for the
vacuum at the mold to reach the right level. Or am I missing
something?

Thanks.


Frank McKenney
--
Nearly every feature of the American system of manufacturing, from
the elements of the new textile machinery to the concept of
interchangeable parts, had actually been conceived earlier by
Europeans. But while a few Europeans could see the possibilities,
their communities kept them powerless to give their ideas a free
trial. Too many had a stake in the older ways. Industrial progress
in Europe required extraordinary courage to break the prevailing
pattern; in America it required a willingness to try the obvious.
American genius was less for invention or discovery than for
experiment.
-- Daniel J. Boorstin / The Americans: The National Experience
--
Frank McKenney, McKenney Associates
Richmond, Virginia / (804) 320-4887
Munged E-mail: frank uscore mckenney aatt mindspring ddoott com

On 4/2/2013 12:38 AM, Ed Huntress wrote:

What Clare is saying, I believe, is that the length of the hose makes
no difference in the value of suction -- if there is no airflow
through the hose. If you hook up a vacuum pump to, say, a bell jar or
to a perfectly sealed vacuum-cure rig for composites, it doesn't
matter how long the hose is. The vacuum will be the same.

What reduces the vacuum is the drag experienced by airflow through the
hose. Longer hoses will measure the same vacuum at their ends, no
matter how long the hose, if there is no flow. But if there is flow,
the more there is, and the greater the inherent drag in the hose, the
lower will be the measured vacuum at the end.

Rules of physics.


Same with electricity.

Vacuum = Voltage.

Length of hose = resistance.

Air mass flow = Current.

On Tuesday, April 2, 2013 7:56:24 AM UTC-4, Frnak McKenney wrote:
On Tue, 02 Apr 2013 01:38:59 -0400, Ed Huntress wrote:

On Tue, 02 Apr 2013 05:32:10 GMT, "Harold & Susan Vordos"

wrote:





wrote in message

. ..

On Mon, 1 Apr 2013 19:41:45 -0700, "Steve B" wrote:



How much does the length of a vacuum hose affect the vacuuming suction?



Steve



Virtually no effect on suction - may reduce flow somewhat. My central

vac pulls the same at the unit in the basement as it does on the

second floor about 15 feet up, using the same 25 foot hose.



We have a Vacuflow 960--twin motors, with the unit capable of handling

18,000 square feet of building.



Length of the tubing most assuredly makes a difference. The vacuum cleaner

is located in the shop, with tubing extended (underground) to the

house--with the longest runs likely near 100'. There's an obvious

difference of performance in the house as opposed to in the shop. 2"

inside diameter pipe, if you have a question on size.



The rules of physics dictate that there will be losses.



Harold



What Clare is saying, I believe, is that the length of the hose

makes no difference in the value of suction -- if there is no

airflow through the hose. If you hook up a vacuum pump to, say, a

bell jar or to a perfectly sealed vacuum-cure rig for composites, it

doesn't matter how long the hose is. The vacuum will be the same.



What reduces the vacuum is the drag experienced by airflow through

the hose. Longer hoses will measure the same vacuum at their ends,

no matter how long the hose, if there is no flow. But if there is

flow, the more there is, and the greater the inherent drag in the

hose, the lower will be the measured vacuum at the end.



Rules of physics.



So... the implication is that "performance" here implies "time", much

like charging a capacitor. Hooking a capacitor across a battery with

voltage "V" will eventually charge the capacitor to "V"; putting a

resistor in series with the capacitor won't affect the final potential

across the capacitor: it will still eventually reach V. However, it

may take longer... perhaps a _lot_ longer. grin!



Makes sense: If I have a "vacuum-formed plastic object" production

line, I probably care whether it takes minutes, hours, or days for the

vacuum at the mold to reach the right level. Or am I missing

something?



Thanks.





Frank McKenney

--

Nearly every feature of the American system of manufacturing, from

the elements of the new textile machinery to the concept of

interchangeable parts, had actually been conceived earlier by

Europeans. But while a few Europeans could see the possibilities,

their communities kept them powerless to give their ideas a free

trial. Too many had a stake in the older ways. Industrial progress

in Europe required extraordinary courage to break the prevailing

pattern; in America it required a willingness to try the obvious.

American genius was less for invention or discovery than for

experiment.

-- Daniel J. Boorstin / The Americans: The National Experience

--

Frank McKenney, McKenney Associates

Richmond, Virginia / (804) 320-4887

Munged E-mail: frank uscore mckenney aatt mindspring ddoott com

It all depends on what you are doing- vacuuming stuff up requires a lot of air flowing quickly, you would need significantly less volume flow to quickly evacuate a mold. But, a long hose would give a lot more space you'd have to pull air out of, so the most significant effect wouldn't be from the drag of the hose, but the volume in it.

On Tue, 02 Apr 2013 06:56:24 -0500, Frnak McKenney
wrote:

On Tue, 02 Apr 2013 01:38:59 -0400, Ed Huntress wrote:
On Tue, 02 Apr 2013 05:32:10 GMT, "Harold & Susan Vordos"
wrote:


wrote in message
...
On Mon, 1 Apr 2013 19:41:45 -0700, "Steve B" wrote:

How much does the length of a vacuum hose affect the vacuuming suction?

Steve

Virtually no effect on suction - may reduce flow somewhat. My central
vac pulls the same at the unit in the basement as it does on the
second floor about 15 feet up, using the same 25 foot hose.

We have a Vacuflow 960--twin motors, with the unit capable of handling
18,000 square feet of building.

Length of the tubing most assuredly makes a difference. The vacuum cleaner
is located in the shop, with tubing extended (underground) to the
house--with the longest runs likely near 100'. There's an obvious
difference of performance in the house as opposed to in the shop. 2"
inside diameter pipe, if you have a question on size.

The rules of physics dictate that there will be losses.

Harold

What Clare is saying, I believe, is that the length of the hose
makes no difference in the value of suction -- if there is no
airflow through the hose. If you hook up a vacuum pump to, say, a
bell jar or to a perfectly sealed vacuum-cure rig for composites, it
doesn't matter how long the hose is. The vacuum will be the same.

What reduces the vacuum is the drag experienced by airflow through
the hose. Longer hoses will measure the same vacuum at their ends,
no matter how long the hose, if there is no flow. But if there is
flow, the more there is, and the greater the inherent drag in the
hose, the lower will be the measured vacuum at the end.

Rules of physics.

So... the implication is that "performance" here implies "time", much
like charging a capacitor. Hooking a capacitor across a battery with
voltage "V" will eventually charge the capacitor to "V"; putting a
resistor in series with the capacitor won't affect the final potential
across the capacitor: it will still eventually reach V. However, it
may take longer... perhaps a _lot_ longer. grin!

Right.


Makes sense: If I have a "vacuum-formed plastic object" production
line, I probably care whether it takes minutes, hours, or days for the
vacuum at the mold to reach the right level. Or am I missing
something?

The vacuum-forming rigs I've seen have to pull full vauum within
seconds, or the plastic would be too far from the heating element for
the thing to work. So I have some trouble relating to your example.

However, it looks like we're all saying much the same thing in
different ways. The effect of hose length on any vacuum system depends
on how much air you're pulling through it. If the flow rate is very
low -- for example, if you're just dealing with the slow leak in a
good vacuum-cure composite bag -- then hose length matters little. If
you're trying to vacuum the dirt off of your kitchen floor, which
requires a very high flow rate, the longer hose presents more friction
to the air flow and reduces the vacuum reading you would get, if you
measured it, at the terminal end of the hose.

--
Ed Huntress


Thanks.


Frank McKenney
--
Nearly every feature of the American system of manufacturing, from
the elements of the new textile machinery to the concept of
interchangeable parts, had actually been conceived earlier by
Europeans. But while a few Europeans could see the possibilities,
their communities kept them powerless to give their ideas a free
trial. Too many had a stake in the older ways. Industrial progress
in Europe required extraordinary courage to break the prevailing
pattern; in America it required a willingness to try the obvious.
American genius was less for invention or discovery than for
experiment.
-- Daniel J. Boorstin / The Americans: The National Experience

Measuring the vacuum at the hose nozzle on the kitchen floor may require
something a bit more sophisticated than just taking a reading at the nozzle,
since there needs to be a significant flow, but partial blockage, for the
vacuum to lift any dirt. (the gap of the nozzle at the floor relates to how
effectively the appliance pulls in dirt). With the nozzle elevated to 3"
above a floor/hard surface, would create a dramatic difference in
efficiency.

Something similar to a leakdown tester comparison may be helpful, indicating
readings of the actual vacuum at the appliance inlet, and simultaneous
reading at the nozzle on the floor with some percentage of restriction to
flow.

Partial blockage of the flow generally results in the turbine motor speeding
up (powered with a brushed universal motor), so that's another factor, I
'spose.

Vacuuming dirt from a horizontal screen surface would be a horse of a
different flavor.

--
WB
..........


"Ed Huntress" wrote in message
...

The vacuum-forming rigs I've seen have to pull full vauum within
seconds, or the plastic would be too far from the heating element for
the thing to work. So I have some trouble relating to your example.

However, it looks like we're all saying much the same thing in
different ways. The effect of hose length on any vacuum system depends
on how much air you're pulling through it. If the flow rate is very
low -- for example, if you're just dealing with the slow leak in a
good vacuum-cure composite bag -- then hose length matters little. If
you're trying to vacuum the dirt off of your kitchen floor, which
requires a very high flow rate, the longer hose presents more friction
to the air flow and reduces the vacuum reading you would get, if you
measured it, at the terminal end of the hose.

--
Ed Huntress

"Richard" wrote in message ...
On 4/2/2013 12:38 AM, Ed Huntress wrote:

What Clare is saying, I believe, is that the length of the hose makes
no difference in the value of suction -- if there is no airflow
through the hose. If you hook up a vacuum pump to, say, a bell jar or
to a perfectly sealed vacuum-cure rig for composites, it doesn't
matter how long the hose is. The vacuum will be the same.

What reduces the vacuum is the drag experienced by airflow through the
hose. Longer hoses will measure the same vacuum at their ends, no
matter how long the hose, if there is no flow. But if there is flow,
the more there is, and the greater the inherent drag in the hose, the
lower will be the measured vacuum at the end.

Rules of physics.


Same with electricity.

Vacuum = Voltage.

Length of hose = resistance.

Air mass flow = Current.

http://en.wikipedia.org/wiki/Reynolds_number

On Mon, 01 Apr 2013 23:43:57 -0400, wrote:

On Mon, 1 Apr 2013 19:41:45 -0700, "Steve B" wrote:

How much does the length of a vacuum hose affect the vacuuming suction?

Steve

Virtually no effect on suction - may reduce flow somewhat. My central
vac pulls the same at the unit in the basement as it does on the
second floor about 15 feet up, using the same 25 foot hose.
Now before anyone says "of course, the length is the same" - no it's
not. There is an extra15 to 20 feet of "hardline" leading to the
upstairs.

On Tue, 02 Apr 2013 01:38:59 -0400, Ed Huntress
wrote:

On Tue, 02 Apr 2013 05:32:10 GMT, "Harold & Susan Vordos"
wrote:


wrote in message
. ..
On Mon, 1 Apr 2013 19:41:45 -0700, "Steve B" wrote:

How much does the length of a vacuum hose affect the vacuuming suction?

Steve

Virtually no effect on suction - may reduce flow somewhat. My central
vac pulls the same at the unit in the basement as it does on the
second floor about 15 feet up, using the same 25 foot hose.

We have a Vacuflow 960--twin motors, with the unit capable of handling
18,000 square feet of building.

Length of the tubing most assuredly makes a difference. The vacuum cleaner
is located in the shop, with tubing extended (underground) to the
house--with the longest runs likely near 100'. There's an obvious
difference of performance in the house as opposed to in the shop. 2"
inside diameter pipe, if you have a question on size.

The rules of physics dictate that there will be losses.

Harold

What Clare is saying, I believe, is that the length of the hose makes
no difference in the value of suction -- if there is no airflow
through the hose. If you hook up a vacuum pump to, say, a bell jar or
to a perfectly sealed vacuum-cure rig for composites, it doesn't
matter how long the hose is. The vacuum will be the same.

What reduces the vacuum is the drag experienced by airflow through the
hose. Longer hoses will measure the same vacuum at their ends, no
matter how long the hose, if there is no flow. But if there is flow,
the more there is, and the greater the inherent drag in the hose, the
lower will be the measured vacuum at the end.

Rules of physics.
Change "no flow" to "restricted flow" - as long as the nozzle is
smaller than the hose diameter so the nozzle restriction excedes the
hose restriction.

On Tue, 02 Apr 2013 06:56:24 -0500, Frnak McKenney
wrote:

On Tue, 02 Apr 2013 01:38:59 -0400, Ed Huntress wrote:
On Tue, 02 Apr 2013 05:32:10 GMT, "Harold & Susan Vordos"
wrote:


wrote in message
...
On Mon, 1 Apr 2013 19:41:45 -0700, "Steve B" wrote:

How much does the length of a vacuum hose affect the vacuuming suction?

Steve

Virtually no effect on suction - may reduce flow somewhat. My central
vac pulls the same at the unit in the basement as it does on the
second floor about 15 feet up, using the same 25 foot hose.

We have a Vacuflow 960--twin motors, with the unit capable of handling
18,000 square feet of building.

Length of the tubing most assuredly makes a difference. The vacuum cleaner
is located in the shop, with tubing extended (underground) to the
house--with the longest runs likely near 100'. There's an obvious
difference of performance in the house as opposed to in the shop. 2"
inside diameter pipe, if you have a question on size.

The rules of physics dictate that there will be losses.

Harold

What Clare is saying, I believe, is that the length of the hose
makes no difference in the value of suction -- if there is no
airflow through the hose. If you hook up a vacuum pump to, say, a
bell jar or to a perfectly sealed vacuum-cure rig for composites, it
doesn't matter how long the hose is. The vacuum will be the same.

What reduces the vacuum is the drag experienced by airflow through
the hose. Longer hoses will measure the same vacuum at their ends,
no matter how long the hose, if there is no flow. But if there is
flow, the more there is, and the greater the inherent drag in the
hose, the lower will be the measured vacuum at the end.

Rules of physics.

So... the implication is that "performance" here implies "time", much
like charging a capacitor. Hooking a capacitor across a battery with
voltage "V" will eventually charge the capacitor to "V"; putting a
resistor in series with the capacitor won't affect the final potential
across the capacitor: it will still eventually reach V. However, it
may take longer... perhaps a _lot_ longer. grin!

Makes sense: If I have a "vacuum-formed plastic object" production
line, I probably care whether it takes minutes, hours, or days for the
vacuum at the mold to reach the right level. Or am I missing
something?

Thanks.


Frank McKenney

The size of the hose matters a lot more than the length in that
situation. You can use a 2 1/4" diameter hose 5 feet or 50 feet long
with only a very small effect on the "performance" of your vacuum
former, as long as the hose cannot shrink or collapse, but put in a
restriction to 1/4", whether it is 1/8" long or 3 inches long, and
you will see a huge drop in performance. Your final mould pressure
will be the same, but the plastic will have a lot more time to cool
down with the restriction. Even a restriction to 1 inch will make a
measurable difference if the vac former is large enough.
--
Nearly every feature of the American system of manufacturing, from
the elements of the new textile machinery to the concept of
interchangeable parts, had actually been conceived earlier by
Europeans. But while a few Europeans could see the possibilities,
their communities kept them powerless to give their ideas a free
trial. Too many had a stake in the older ways. Industrial progress
in Europe required extraordinary courage to break the prevailing
pattern; in America it required a willingness to try the obvious.
American genius was less for invention or discovery than for
experiment.
-- Daniel J. Boorstin / The Americans: The National Experience

On Tue, 02 Apr 2013 07:37:34 -0500, Richard
wrote:

On 4/2/2013 12:38 AM, Ed Huntress wrote:

What Clare is saying, I believe, is that the length of the hose makes
no difference in the value of suction -- if there is no airflow
through the hose. If you hook up a vacuum pump to, say, a bell jar or
to a perfectly sealed vacuum-cure rig for composites, it doesn't
matter how long the hose is. The vacuum will be the same.

What reduces the vacuum is the drag experienced by airflow through the
hose. Longer hoses will measure the same vacuum at their ends, no
matter how long the hose, if there is no flow. But if there is flow,
the more there is, and the greater the inherent drag in the hose, the
lower will be the measured vacuum at the end.

Rules of physics.


Same with electricity.

Vacuum = Voltage.

Length of hose = resistance.

Air mass flow = Current.

But if the resistance per circular mil foot is relatively low, and the
conductor guage(number of circular mils) is high enough, the number of
feet becomes a very small part of the equation. IE, if you have a 5
amp load on a 12 ga conductor 5 feet or 500 feet in length, it's going
to take a sensitive instrument to read the difference. Put 30 amps on
a 22 ga wire and the difference between 5 feet and 15 will be readily
discernable (if the wire lasts long enough to measure it )

On Tue, 2 Apr 2013 06:18:13 -0700 (PDT), wrote:

On Tuesday, April 2, 2013 7:56:24 AM UTC-4, Frnak McKenney wrote:
On Tue, 02 Apr 2013 01:38:59 -0400, Ed Huntress wrote:

On Tue, 02 Apr 2013 05:32:10 GMT, "Harold & Susan Vordos"

wrote:





wrote in message

. ..

On Mon, 1 Apr 2013 19:41:45 -0700, "Steve B" wrote:



How much does the length of a vacuum hose affect the vacuuming suction?



Steve



Virtually no effect on suction - may reduce flow somewhat. My central

vac pulls the same at the unit in the basement as it does on the

second floor about 15 feet up, using the same 25 foot hose.



We have a Vacuflow 960--twin motors, with the unit capable of handling

18,000 square feet of building.



Length of the tubing most assuredly makes a difference. The vacuum cleaner

is located in the shop, with tubing extended (underground) to the

house--with the longest runs likely near 100'. There's an obvious

difference of performance in the house as opposed to in the shop. 2"

inside diameter pipe, if you have a question on size.



The rules of physics dictate that there will be losses.



Harold



What Clare is saying, I believe, is that the length of the hose

makes no difference in the value of suction -- if there is no

airflow through the hose. If you hook up a vacuum pump to, say, a

bell jar or to a perfectly sealed vacuum-cure rig for composites, it

doesn't matter how long the hose is. The vacuum will be the same.



What reduces the vacuum is the drag experienced by airflow through

the hose. Longer hoses will measure the same vacuum at their ends,

no matter how long the hose, if there is no flow. But if there is

flow, the more there is, and the greater the inherent drag in the

hose, the lower will be the measured vacuum at the end.



Rules of physics.



So... the implication is that "performance" here implies "time", much

like charging a capacitor. Hooking a capacitor across a battery with

voltage "V" will eventually charge the capacitor to "V"; putting a

resistor in series with the capacitor won't affect the final potential

across the capacitor: it will still eventually reach V. However, it

may take longer... perhaps a _lot_ longer. grin!



Makes sense: If I have a "vacuum-formed plastic object" production

line, I probably care whether it takes minutes, hours, or days for the

vacuum at the mold to reach the right level. Or am I missing

something?



Thanks.





Frank McKenney

--

Nearly every feature of the American system of manufacturing, from

the elements of the new textile machinery to the concept of

interchangeable parts, had actually been conceived earlier by

Europeans. But while a few Europeans could see the possibilities,

their communities kept them powerless to give their ideas a free

trial. Too many had a stake in the older ways. Industrial progress

in Europe required extraordinary courage to break the prevailing

pattern; in America it required a willingness to try the obvious.

American genius was less for invention or discovery than for

experiment.

-- Daniel J. Boorstin / The Americans: The National Experience

--

Frank McKenney, McKenney Associates

Richmond, Virginia / (804) 320-4887

Munged E-mail: frank uscore mckenney aatt mindspring ddoott com

It all depends on what you are doing- vacuuming stuff up requires a lot of air flowing quickly, you would need significantly less volume flow to quickly evacuate a mold. But, a long hose would give a lot more space you'd have to pull air out of, so the most significant effect wouldn't be from the drag of the hose, but the volume in it.
Which is not an issue if the vac is applied to the hose ahead of
time,with a "gate valve" at the vac former - which is "standard
practice" in production vac forming.

Steve B wrote:
How much does the length of a vacuum hose affect the vacuuming suction?

Steve

Short answer is alot.

the "pressure" available in a vacuum system is usually limited to that of
atmospheric, or 14.7-ish PSI.

That's all you have to work with, and that's only when you start pumping.

Since suction is the flow of gas in this case, you have to factor in the
volume you're trying to move, and it will increase as the pressure drops
making it harder and harder to evacuate.

1 cubic foot of air at sea level takes up 1 cubic foot.

Drop the pressure by half and now this gas takes up 2 cubic feet.

half that again and it's 4 cubic feet.

So you really have to pump out 3 cubic feet of air to drop the pressure in
a 1 foot cube to 1/4th atmospheric pressure.

The resitance of tube or pipe is a big deal at lower pressures. A shopvac
with a 2" hose seems pretty powerful out in the open, but if the pressure
is 0.1" Hg you're just going to get a gentle breeze if even across the
same hose. The same thing happens once pressure in your vacuum system
starts to drop. Everything gets harder and harder to do the more gas you
remove.

So the other short answer is you want the shortest, fattest pipes for
vacuum work, whithin reason for what you're doing.

wrote:
On Tue, 02 Apr 2013 07:37:34 -0500, Richard
wrote:

On 4/2/2013 12:38 AM, Ed Huntress wrote:

What Clare is saying, I believe, is that the length of the hose makes
no difference in the value of suction -- if there is no airflow
through the hose. If you hook up a vacuum pump to, say, a bell jar or
to a perfectly sealed vacuum-cure rig for composites, it doesn't
matter how long the hose is. The vacuum will be the same.

What reduces the vacuum is the drag experienced by airflow through the
hose. Longer hoses will measure the same vacuum at their ends, no
matter how long the hose, if there is no flow. But if there is flow,
the more there is, and the greater the inherent drag in the hose, the
lower will be the measured vacuum at the end.

Rules of physics.


Same with electricity.

Vacuum = Voltage.

Length of hose = resistance.

Air mass flow = Current.

But if the resistance per circular mil foot is relatively low, and the
conductor guage(number of circular mils) is high enough, the number of
feet becomes a very small part of the equation. IE, if you have a 5
amp load on a 12 ga conductor 5 feet or 500 feet in length, it's going
to take a sensitive instrument to read the difference. Put 30 amps on
a 22 ga wire and the difference between 5 feet and 15 will be readily
discernable (if the wire lasts long enough to measure it )

electricity doesn't exactly translate to vacuum stuff, although it's more
accurate than the electricity to liquid in pipes model.

there's far more gas to evacuate from a fat long pipe than a small short
one.

With conductors you just add an electron on one end and another comes out
the other end, you don't have to "fill" the wire first- you don't have to
charge up a wire to get it going, like with a garden hose.

On 4/2/2013 2:19 PM, Cydrome Leader wrote:
wrote:
On Tue, 02 Apr 2013 07:37:34 -0500,
wrote:

On 4/2/2013 12:38 AM, Ed Huntress wrote:

What Clare is saying, I believe, is that the length of the hose makes
no difference in the value of suction -- if there is no airflow
through the hose. If you hook up a vacuum pump to, say, a bell jar or
to a perfectly sealed vacuum-cure rig for composites, it doesn't
matter how long the hose is. The vacuum will be the same.

What reduces the vacuum is the drag experienced by airflow through the
hose. Longer hoses will measure the same vacuum at their ends, no
matter how long the hose, if there is no flow. But if there is flow,
the more there is, and the greater the inherent drag in the hose, the
lower will be the measured vacuum at the end.

Rules of physics.


Same with electricity.

Vacuum = Voltage.

Length of hose = resistance.

Air mass flow = Current.

But if the resistance per circular mil foot is relatively low, and the
conductor guage(number of circular mils) is high enough, the number of
feet becomes a very small part of the equation. IE, if you have a 5
amp load on a 12 ga conductor 5 feet or 500 feet in length, it's going
to take a sensitive instrument to read the difference. Put 30 amps on
a 22 ga wire and the difference between 5 feet and 15 will be readily
discernable (if the wire lasts long enough to measure it )

electricity doesn't exactly translate to vacuum stuff, although it's more
accurate than the electricity to liquid in pipes model.

there's far more gas to evacuate from a fat long pipe than a small short
one.

With conductors you just add an electron on one end and another comes out
the other end, you don't have to "fill" the wire first- you don't have to
charge up a wire to get it going, like with a garden hose.



But if you don't "charge up the wire" how does the electron that goes in
have a place to go in???

"Richard" wrote in message
m...
On 4/2/2013 2:19 PM, Cydrome Leader wrote:

With conductors you just add an electron on one end and another
comes out
the other end, you don't have to "fill" the wire first- you don't
have to
charge up a wire to get it going, like with a garden hose.

But if you don't "charge up the wire" how does the electron that
goes in have a place to go in???

You do have to charge up the capacitance between the wire and the rest
of the universe. It usually isn't enough to notice except for coaxial
cable, which is around 30pF per foot.
http://www.microwaves101.com/encyclopedia/z0.cfm
jsw

On Tue, 2 Apr 2013 19:12:16 +0000 (UTC), Cydrome Leader
wrote:

Steve B wrote:
How much does the length of a vacuum hose affect the vacuuming suction?

Steve

Short answer is alot.

the "pressure" available in a vacuum system is usually limited to that of
atmospheric, or 14.7-ish PSI.

That's all you have to work with, and that's only when you start pumping.

Since suction is the flow of gas in this case, you have to factor in the
volume you're trying to move, and it will increase as the pressure drops
making it harder and harder to evacuate.

1 cubic foot of air at sea level takes up 1 cubic foot.

Drop the pressure by half and now this gas takes up 2 cubic feet.

half that again and it's 4 cubic feet.

So you really have to pump out 3 cubic feet of air to drop the pressure in
a 1 foot cube to 1/4th atmospheric pressure.

The resitance of tube or pipe is a big deal at lower pressures. A shopvac
with a 2" hose seems pretty powerful out in the open, but if the pressure
is 0.1" Hg you're just going to get a gentle breeze if even across the
same hose. The same thing happens once pressure in your vacuum system
starts to drop. Everything gets harder and harder to do the more gas you
remove.

So the other short answer is you want the shortest, fattest pipes for
vacuum work, whithin reason for what you're doing.





Except then you have to remove all the air from the fat pipe too - it
is a catch-22.

On Tue, 02 Apr 2013 12:47:06 -0400, clare wrote:

On Tue, 02 Apr 2013 07:37:34 -0500, Richard
wrote:

On 4/2/2013 12:38 AM, Ed Huntress wrote:

What Clare is saying, I believe, is that the length of the hose makes
no difference in the value of suction -- if there is no airflow
through the hose. If you hook up a vacuum pump to, say, a bell jar or
to a perfectly sealed vacuum-cure rig for composites, it doesn't
matter how long the hose is. The vacuum will be the same.

What reduces the vacuum is the drag experienced by airflow through the
hose. Longer hoses will measure the same vacuum at their ends, no
matter how long the hose, if there is no flow. But if there is flow,
the more there is, and the greater the inherent drag in the hose, the
lower will be the measured vacuum at the end.

Rules of physics.


Same with electricity.

Vacuum = Voltage.

Length of hose = resistance.

Air mass flow = Current.

But if the resistance per circular mil foot is relatively low, and the
conductor guage(number of circular mils) is high enough, the number of
feet becomes a very small part of the equation. IE, if you have a 5
amp load on a 12 ga conductor 5 feet or 500 feet in length, it's going
to take a sensitive instrument to read the difference. Put 30 amps on
a 22 ga wire and the difference between 5 feet and 15 will be readily
discernable (if the wire lasts long enough to measure it )

Bad example! It doesn't take a particularly sensitive voltmeter to
distinguish a four-volt drop from 40 millivolts. 12 ga copper has about
1.6 ohms per thousand feet; 5A * .8 ohms gives 4 volts drop.

Even with gage 0 wire, at 0.1 ohms per thousand feet, there would be a
quarter-volt difference for 5A in a 500' run vs 5' run.

--
jiw

Richard wrote:
On 4/2/2013 2:19 PM, Cydrome Leader wrote:
wrote:
On Tue, 02 Apr 2013 07:37:34 -0500,
wrote:

On 4/2/2013 12:38 AM, Ed Huntress wrote:

What Clare is saying, I believe, is that the length of the hose makes
no difference in the value of suction -- if there is no airflow
through the hose. If you hook up a vacuum pump to, say, a bell jar or
to a perfectly sealed vacuum-cure rig for composites, it doesn't
matter how long the hose is. The vacuum will be the same.

What reduces the vacuum is the drag experienced by airflow through the
hose. Longer hoses will measure the same vacuum at their ends, no
matter how long the hose, if there is no flow. But if there is flow,
the more there is, and the greater the inherent drag in the hose, the
lower will be the measured vacuum at the end.

Rules of physics.


Same with electricity.

Vacuum = Voltage.

Length of hose = resistance.

Air mass flow = Current.

But if the resistance per circular mil foot is relatively low, and the
conductor guage(number of circular mils) is high enough, the number of
feet becomes a very small part of the equation. IE, if you have a 5
amp load on a 12 ga conductor 5 feet or 500 feet in length, it's going
to take a sensitive instrument to read the difference. Put 30 amps on
a 22 ga wire and the difference between 5 feet and 15 will be readily
discernable (if the wire lasts long enough to measure it )

electricity doesn't exactly translate to vacuum stuff, although it's more
accurate than the electricity to liquid in pipes model.

there's far more gas to evacuate from a fat long pipe than a small short
one.

With conductors you just add an electron on one end and another comes out
the other end, you don't have to "fill" the wire first- you don't have to
charge up a wire to get it going, like with a garden hose.



But if you don't "charge up the wire" how does the electron that goes in
have a place to go in???

It's like a bucket brigade through the conductor, sort of like those
swinging ball desk toys from the 1980s. The electron coming "out" of your
wire isn't the same one going in. Materials that are good at doing this,
like metals are great conductors. Others like glass or plastic are bad at
letting current pass through them.

wrote:
On Tue, 2 Apr 2013 19:12:16 +0000 (UTC), Cydrome Leader
wrote:

Steve B wrote:
How much does the length of a vacuum hose affect the vacuuming suction?

Steve

Short answer is alot.

the "pressure" available in a vacuum system is usually limited to that of
atmospheric, or 14.7-ish PSI.

That's all you have to work with, and that's only when you start pumping.

Since suction is the flow of gas in this case, you have to factor in the
volume you're trying to move, and it will increase as the pressure drops
making it harder and harder to evacuate.

1 cubic foot of air at sea level takes up 1 cubic foot.

Drop the pressure by half and now this gas takes up 2 cubic feet.

half that again and it's 4 cubic feet.

So you really have to pump out 3 cubic feet of air to drop the pressure in
a 1 foot cube to 1/4th atmospheric pressure.

The resitance of tube or pipe is a big deal at lower pressures. A shopvac
with a 2" hose seems pretty powerful out in the open, but if the pressure
is 0.1" Hg you're just going to get a gentle breeze if even across the
same hose. The same thing happens once pressure in your vacuum system
starts to drop. Everything gets harder and harder to do the more gas you
remove.

So the other short answer is you want the shortest, fattest pipes for
vacuum work, whithin reason for what you're doing.





Except then you have to remove all the air from the fat pipe too - it
is a catch-22.

yup.

There's got to be some sort of "vacuum impedance" or conductance to volume
matching formula out there, although I can't figure out what's it's even
called.

The Lesker Company has good docs on stuff like that on their website:

http://www.lesker.com/newweb/menu_te...v=ok&le vel=2

It looks like "Effective Pumping Speed" is the matter at hand:

http://www.lesker.com/newweb/Technic...ping&init=skip

The tech support person or people there are REALLY good.

On Tue, 2 Apr 2013 23:16:46 +0000 (UTC), James Waldby
wrote:


You are right - I was off a decimal point.

On 4/2/2013 6:47 PM, Cydrome Leader wrote:
wrote:
On 4/2/2013 2:19 PM, Cydrome Leader wrote:
wrote:
On Tue, 02 Apr 2013 07:37:34 -0500,
wrote:

On 4/2/2013 12:38 AM, Ed Huntress wrote:

What Clare is saying, I believe, is that the length of the hose makes
no difference in the value of suction -- if there is no airflow
through the hose. If you hook up a vacuum pump to, say, a bell jar or
to a perfectly sealed vacuum-cure rig for composites, it doesn't
matter how long the hose is. The vacuum will be the same.

What reduces the vacuum is the drag experienced by airflow through the
hose. Longer hoses will measure the same vacuum at their ends, no
matter how long the hose, if there is no flow. But if there is flow,
the more there is, and the greater the inherent drag in the hose, the
lower will be the measured vacuum at the end.

Rules of physics.


Same with electricity.

Vacuum = Voltage.

Length of hose = resistance.

Air mass flow = Current.

But if the resistance per circular mil foot is relatively low, and the
conductor guage(number of circular mils) is high enough, the number of
feet becomes a very small part of the equation. IE, if you have a 5
amp load on a 12 ga conductor 5 feet or 500 feet in length, it's going
to take a sensitive instrument to read the difference. Put 30 amps on
a 22 ga wire and the difference between 5 feet and 15 will be readily
discernable (if the wire lasts long enough to measure it )

electricity doesn't exactly translate to vacuum stuff, although it's more
accurate than the electricity to liquid in pipes model.

there's far more gas to evacuate from a fat long pipe than a small short
one.

With conductors you just add an electron on one end and another comes out
the other end, you don't have to "fill" the wire first- you don't have to
charge up a wire to get it going, like with a garden hose.



But if you don't "charge up the wire" how does the electron that goes in
have a place to go in???

It's like a bucket brigade through the conductor, sort of like those
swinging ball desk toys from the 1980s. The electron coming "out" of your
wire isn't the same one going in. Materials that are good at doing this,
like metals are great conductors. Others like glass or plastic are bad at
letting current pass through them.



Yabut, so like the vacuum hose (for a while anyway)

It's just a matter of scale (Reynolds)

"Cydrome Leader" wrote in message
news:kjfr4n$g26

There's got to be some sort of "vacuum impedance" or conductance to
volume
matching formula out there, although I can't figure out what's it's
even
called.


http://www.engineeringtoolbox.com/fl...nts-d_277.html

jsw

Jim Wilkins wrote:
"Cydrome Leader" wrote in message
news:kjfr4n$g26

There's got to be some sort of "vacuum impedance" or conductance to
volume
matching formula out there, although I can't figure out what's it's
even
called.


http://www.engineeringtoolbox.com/fl...nts-d_277.html

jsw

The ones listed there seen to be for the constant flow of
gas/steam/liquid. The problem is the pressure isn't constant in a pumpdown
scenario.

Sometimes when I post I feel like the "Samuel F. B. Morse" of MAD
magazine fame:

"What hath got wrought?"

On Tue, 02 Apr 2013 10:19:41 -0400, Ed Huntress wrote:
On Tue, 02 Apr 2013 06:56:24 -0500, Frnak McKenney
wrote:

[...]

So... the implication is that "performance" here implies "time", much
like charging a capacitor. Hooking a capacitor across a battery with
voltage "V" will eventually charge the capacitor to "V"; putting a
resistor in series with the capacitor won't affect the final potential
across the capacitor: it will still eventually reach V. However, it
may take longer... perhaps a _lot_ longer. grin!

Right.

Makes sense: If I have a "vacuum-formed plastic object" production
line, I probably care whether it takes minutes, hours, or days for the
vacuum at the mold to reach the right level. Or am I missing
something?

The vacuum-forming rigs I've seen have to pull full vauum within
seconds, or the plastic would be too far from the heating element for
the thing to work. ...

Eureka! ( Which is apparently Greek for "A minor crack in my otherwise
impermeable wall of ignorance is dimly illuminating the back of the
cave." grin! ) "Flow". "Rate".

... So I have some trouble relating to your example.

Sorry. After reading the folowups I think I can clarify ( famous last
word! ) the source of my confusion. I had been reading all the
references to "vacuum" and interpreting them as "end-state air
pressure", a static value vaguely analogous to the end-state potential
across a capacitor in a DC circuit. Depending on the circuit
resistance, the capacitance, and the potential feeding the circuit
this can take femtoseconds or gigayears ( though the latter doesn't
seem all that useful grin! ).

However, it looks like we're all saying much the same thing in
different ways. The effect of hose length on any vacuum system
depends on how much air you're pulling through it. If the flow rate
is very low -- for example, if you're just dealing with the slow
leak in a good vacuum-cure composite bag -- then hose length matters
little. If you're trying to vacuum the dirt off of your kitchen
floor, which requires a very high flow rate, the longer hose
presents more friction to the air flow and reduces the vacuum
reading you would get, if you measured it, at the terminal end of
the hose.

Agreed; an analogous electronic circuit would have a lot of leakage
over, under, around, or through something. grin!

My apologies to all for the distraction from the subject at hand.


Frank
--
It's not what we don't know that gives us trouble, it's what
we know that ain't so. -- Will Rogers
--
Frank McKenney, McKenney Associates
Richmond, Virginia / (804) 320-4887
Munged E-mail: frank uscore mckenney aatt mindspring ddoott com

On 4/1/2013 10:41 PM, Steve B wrote:
How much does the length of a vacuum hose affect the vacuuming suction?


An example: my 5 hp leaf vac has a 6" dia hose, 6' long. The "vacuuming
suction" is very good. I thought a 12' hose would be more convenient
and added another 6'. The resulting vacuuming suction was so poor as to
be useless.

Bob

On Wed, 03 Apr 2013 17:18:04 -0500, Frnak McKenney
wrote:

Sometimes when I post I feel like the "Samuel F. B. Morse" of MAD
magazine fame:

"What hath got wrought?"

On Tue, 02 Apr 2013 10:19:41 -0400, Ed Huntress wrote:
On Tue, 02 Apr 2013 06:56:24 -0500, Frnak McKenney
wrote:

[...]

So... the implication is that "performance" here implies "time", much
like charging a capacitor. Hooking a capacitor across a battery with
voltage "V" will eventually charge the capacitor to "V"; putting a
resistor in series with the capacitor won't affect the final potential
across the capacitor: it will still eventually reach V. However, it
may take longer... perhaps a _lot_ longer. grin!

Right.

Makes sense: If I have a "vacuum-formed plastic object" production
line, I probably care whether it takes minutes, hours, or days for the
vacuum at the mold to reach the right level. Or am I missing
something?

The vacuum-forming rigs I've seen have to pull full vauum within
seconds, or the plastic would be too far from the heating element for
the thing to work. ...

Eureka! ( Which is apparently Greek for "A minor crack in my otherwise
impermeable wall of ignorance is dimly illuminating the back of the
cave." grin! ) "Flow". "Rate".

... So I have some trouble relating to your example.

Sorry. After reading the folowups I think I can clarify ( famous last
word! ) the source of my confusion. I had been reading all the
references to "vacuum" and interpreting them as "end-state air
pressure", a static value vaguely analogous to the end-state potential
across a capacitor in a DC circuit. Depending on the circuit
resistance, the capacitance, and the potential feeding the circuit
this can take femtoseconds or gigayears ( though the latter doesn't
seem all that useful grin! ).

However, it looks like we're all saying much the same thing in
different ways. The effect of hose length on any vacuum system
depends on how much air you're pulling through it. If the flow rate
is very low -- for example, if you're just dealing with the slow
leak in a good vacuum-cure composite bag -- then hose length matters
little. If you're trying to vacuum the dirt off of your kitchen
floor, which requires a very high flow rate, the longer hose
presents more friction to the air flow and reduces the vacuum
reading you would get, if you measured it, at the terminal end of
the hose.

Agreed; an analogous electronic circuit would have a lot of leakage
over, under, around, or through something. grin!

My apologies to all for the distraction from the subject at hand.

Well, I don't think it was a distraction. This is something that may
sound simple on the surface but which benefits by looking at it from a
variety of angles.

For example, I just had to use my shop vac to get the leaves out of my
English ivy. That results in a lot of flow and fighting to keep the
vacuum up with lots of leaves jamming everything up. d8-)

--
Ed Huntress



Frank
--
It's not what we don't know that gives us trouble, it's what
we know that ain't so. -- Will Rogers

Cydrome Leader wrote:

It's like a bucket brigade through the conductor, sort of like those
swinging ball desk toys from the 1980s. The electron coming "out" of your
wire isn't the same one going in. Materials that are good at doing this,
like metals are great conductors. Others like glass or plastic are bad at
letting current pass through them.


Conductive plastic is used as the shield for some cables. Like foil,
it needs a drain wire to be able to connect it to ground.


--

Politicians should only get paid if the budget is balanced, and there is
enough left over to pay them.

Sometimes Friday is just the fifth Monday of the week.

wrote:

On Mon, 01 Apr 2013 23:43:57 -0400, wrote:

On Mon, 1 Apr 2013 19:41:45 -0700, "Steve B" wrote:

How much does the length of a vacuum hose affect the vacuuming suction?

Steve

Virtually no effect on suction - may reduce flow somewhat. My central
vac pulls the same at the unit in the basement as it does on the
second floor about 15 feet up, using the same 25 foot hose.
Now before anyone says "of course, the length is the same" - no it's
not. There is an extra15 to 20 feet of "hardline" leading to the
upstairs.


The line to the upper floor has the advantage of gravity and the mass
of the air in the pipe. You need a flow gauge to see the difference.


--

Politicians should only get paid if the budget is balanced, and there is
enough left over to pay them.

Sometimes Friday is just the fifth Monday of the week.

On Thu, 04 Apr 2013 07:02:44 -0400, "Michael A. Terrell"
wrote:


wrote:

On Mon, 01 Apr 2013 23:43:57 -0400, wrote:

On Mon, 1 Apr 2013 19:41:45 -0700, "Steve B" wrote:

How much does the length of a vacuum hose affect the vacuuming suction?

Steve

Virtually no effect on suction - may reduce flow somewhat. My central
vac pulls the same at the unit in the basement as it does on the
second floor about 15 feet up, using the same 25 foot hose.
Now before anyone says "of course, the length is the same" - no it's
not. There is an extra15 to 20 feet of "hardline" leading to the
upstairs.


The line to the upper floor has the advantage of gravity and the mass
of the air in the pipe. You need a flow gauge to see the difference.

Not a factor.

--
Ed Huntress