OT: Physics/hydraulics of water and barrel
11-24-2004, 10:45 PM
#151
Guest
Posts: n/a
Re: OT: Physics/hydraulics of water and barrel
lazolla@hotmail.com (Bartolomeo Cristofori) wrote in message news:<93a0508e.0411241244.70fbb744@posting.google. com>...
> The physics is simple.
>
> If the hose is of the proper diameter for the flow rate generated by
> the pump, then the pressure at the pump will be about equal to the
> vertical distance (the height) between the pump and the point where
> the water becomes free-flowing, times a density value of about .45
> PSI/ft (which is derived from the weight of a cubic foot of water
> divided by 144 to convert from square feet to square inches). If you
> are pumping the water to the top of the barrel and letting it fall,
> then that would be the height difference between the pump and the top
> of the barrel. If you are pumping the water into the bottom bung,
> then you would use the height difference between the pump and the top
> of the water in the barrel.
>
> Therefore, the pump would encounter slightly less pressure if the tank
> were filled through the bottom bung, at least until it became nearly
> full. The difference is small enough that it would make only a small
> change in the amount of time it would take to fill the tank.
>
> The fact that there may be several hundred pounds of water in the
> barrel is immaterial, since pressure is pounds per square inch. You
> could calculate the pressure at the bottom of the barrel by dividing
> the weight of the water in the barrel by the area of the barrel head
> in square inches (assuming straight sides, for a wooden barrel you
> would have to use an average diameter to get an exact figure).
>
> Bartolomeo
Ah yes, finally the proper answer, i.e, it is slightly less pressure
to begin with to fill thru the bottom hole until it is identical when
the barrel is full. Assuming the barrel is about 4' high there would
be about 2psi differential pumping pressure at the bottom of the empty
barrel than at shutoff when it is full. Filling through the top hole
will have the same pressure of whatever throughout the filling.
Harry K
> The physics is simple.
>
> If the hose is of the proper diameter for the flow rate generated by
> the pump, then the pressure at the pump will be about equal to the
> vertical distance (the height) between the pump and the point where
> the water becomes free-flowing, times a density value of about .45
> PSI/ft (which is derived from the weight of a cubic foot of water
> divided by 144 to convert from square feet to square inches). If you
> are pumping the water to the top of the barrel and letting it fall,
> then that would be the height difference between the pump and the top
> of the barrel. If you are pumping the water into the bottom bung,
> then you would use the height difference between the pump and the top
> of the water in the barrel.
>
> Therefore, the pump would encounter slightly less pressure if the tank
> were filled through the bottom bung, at least until it became nearly
> full. The difference is small enough that it would make only a small
> change in the amount of time it would take to fill the tank.
>
> The fact that there may be several hundred pounds of water in the
> barrel is immaterial, since pressure is pounds per square inch. You
> could calculate the pressure at the bottom of the barrel by dividing
> the weight of the water in the barrel by the area of the barrel head
> in square inches (assuming straight sides, for a wooden barrel you
> would have to use an average diameter to get an exact figure).
>
> Bartolomeo
Ah yes, finally the proper answer, i.e, it is slightly less pressure
to begin with to fill thru the bottom hole until it is identical when
the barrel is full. Assuming the barrel is about 4' high there would
be about 2psi differential pumping pressure at the bottom of the empty
barrel than at shutoff when it is full. Filling through the top hole
will have the same pressure of whatever throughout the filling.
Harry K
11-24-2004, 10:48 PM
#152
Guest
Posts: n/a
Re: Physics/hydraulics of water and barrel
"Ray Drouillard" <cosmicpam2@comcast.net> wrote in message news:<30kjsgF31btgjU1@uni-berlin.de>...
> "Tom Quackenbush" <tquackenbogusinfo@kingcon.com> wrote in message
> news:pmq9q0l4sjckqakm5b9sma5mdlptajk6fp@4ax.com...
> > Jeepers wrote:
> > <snip>
> >
> > >O.K. my lame-*** attempt at physics argument:
> > >
> > >Isn't part of the column the barrel? The barrel has a bigger column
> in
> > >it's part, than the hose. So the weight of the water column is
> GREATLY
> > >larger than the one in the hose going to the top. Less water - less
> > >weight, right?
> >
> > Nope. When we speak of a column in this context, the column has the
> > same area as the hose through which you're pumping fluid. If you
> > wanted to know the pressure in pounds per square inch, you'd consider
> > an imaginary coulumn with a cross-sectional area of 1 square inch.
> >
> > The volume of fluid outside the column doesn't matter.
> >
> > Consider this:
> >
> > If you submerge yourself one foot under water in your swimming pool,
> > you're subject to the same pressure as if you were submerged one foot
> > under water in Lake Superior, even though the volume of Lake Superior
> > is a gazillion times larger than your swimming pool (gazillion being a
> > highly technical term used for these sorts of comparisons).
>
> If you submerge yourself a foot under water in Lake Superior, you had
> better be related to the polar bear. ;-)
>
>
> Ray Drouillard
And the pressure might go up a bit as density does go up a small
amount for colder water. Densist at 4 degree (F or C?) IIRC from 50
years ago.
Harry K
> "Tom Quackenbush" <tquackenbogusinfo@kingcon.com> wrote in message
> news:pmq9q0l4sjckqakm5b9sma5mdlptajk6fp@4ax.com...
> > Jeepers wrote:
> > <snip>
> >
> > >O.K. my lame-*** attempt at physics argument:
> > >
> > >Isn't part of the column the barrel? The barrel has a bigger column
> in
> > >it's part, than the hose. So the weight of the water column is
> GREATLY
> > >larger than the one in the hose going to the top. Less water - less
> > >weight, right?
> >
> > Nope. When we speak of a column in this context, the column has the
> > same area as the hose through which you're pumping fluid. If you
> > wanted to know the pressure in pounds per square inch, you'd consider
> > an imaginary coulumn with a cross-sectional area of 1 square inch.
> >
> > The volume of fluid outside the column doesn't matter.
> >
> > Consider this:
> >
> > If you submerge yourself one foot under water in your swimming pool,
> > you're subject to the same pressure as if you were submerged one foot
> > under water in Lake Superior, even though the volume of Lake Superior
> > is a gazillion times larger than your swimming pool (gazillion being a
> > highly technical term used for these sorts of comparisons).
>
> If you submerge yourself a foot under water in Lake Superior, you had
> better be related to the polar bear. ;-)
>
>
> Ray Drouillard
And the pressure might go up a bit as density does go up a small
amount for colder water. Densist at 4 degree (F or C?) IIRC from 50
years ago.
Harry K
11-24-2004, 10:48 PM
#153
Guest
Posts: n/a
Re: Physics/hydraulics of water and barrel
"Ray Drouillard" <cosmicpam2@comcast.net> wrote in message news:<30kjsgF31btgjU1@uni-berlin.de>...
> "Tom Quackenbush" <tquackenbogusinfo@kingcon.com> wrote in message
> news:pmq9q0l4sjckqakm5b9sma5mdlptajk6fp@4ax.com...
> > Jeepers wrote:
> > <snip>
> >
> > >O.K. my lame-*** attempt at physics argument:
> > >
> > >Isn't part of the column the barrel? The barrel has a bigger column
> in
> > >it's part, than the hose. So the weight of the water column is
> GREATLY
> > >larger than the one in the hose going to the top. Less water - less
> > >weight, right?
> >
> > Nope. When we speak of a column in this context, the column has the
> > same area as the hose through which you're pumping fluid. If you
> > wanted to know the pressure in pounds per square inch, you'd consider
> > an imaginary coulumn with a cross-sectional area of 1 square inch.
> >
> > The volume of fluid outside the column doesn't matter.
> >
> > Consider this:
> >
> > If you submerge yourself one foot under water in your swimming pool,
> > you're subject to the same pressure as if you were submerged one foot
> > under water in Lake Superior, even though the volume of Lake Superior
> > is a gazillion times larger than your swimming pool (gazillion being a
> > highly technical term used for these sorts of comparisons).
>
> If you submerge yourself a foot under water in Lake Superior, you had
> better be related to the polar bear. ;-)
>
>
> Ray Drouillard
And the pressure might go up a bit as density does go up a small
amount for colder water. Densist at 4 degree (F or C?) IIRC from 50
years ago.
Harry K
> "Tom Quackenbush" <tquackenbogusinfo@kingcon.com> wrote in message
> news:pmq9q0l4sjckqakm5b9sma5mdlptajk6fp@4ax.com...
> > Jeepers wrote:
> > <snip>
> >
> > >O.K. my lame-*** attempt at physics argument:
> > >
> > >Isn't part of the column the barrel? The barrel has a bigger column
> in
> > >it's part, than the hose. So the weight of the water column is
> GREATLY
> > >larger than the one in the hose going to the top. Less water - less
> > >weight, right?
> >
> > Nope. When we speak of a column in this context, the column has the
> > same area as the hose through which you're pumping fluid. If you
> > wanted to know the pressure in pounds per square inch, you'd consider
> > an imaginary coulumn with a cross-sectional area of 1 square inch.
> >
> > The volume of fluid outside the column doesn't matter.
> >
> > Consider this:
> >
> > If you submerge yourself one foot under water in your swimming pool,
> > you're subject to the same pressure as if you were submerged one foot
> > under water in Lake Superior, even though the volume of Lake Superior
> > is a gazillion times larger than your swimming pool (gazillion being a
> > highly technical term used for these sorts of comparisons).
>
> If you submerge yourself a foot under water in Lake Superior, you had
> better be related to the polar bear. ;-)
>
>
> Ray Drouillard
And the pressure might go up a bit as density does go up a small
amount for colder water. Densist at 4 degree (F or C?) IIRC from 50
years ago.
Harry K
11-24-2004, 10:48 PM
#154
Guest
Posts: n/a
Re: Physics/hydraulics of water and barrel
"Ray Drouillard" <cosmicpam2@comcast.net> wrote in message news:<30kjsgF31btgjU1@uni-berlin.de>...
> "Tom Quackenbush" <tquackenbogusinfo@kingcon.com> wrote in message
> news:pmq9q0l4sjckqakm5b9sma5mdlptajk6fp@4ax.com...
> > Jeepers wrote:
> > <snip>
> >
> > >O.K. my lame-*** attempt at physics argument:
> > >
> > >Isn't part of the column the barrel? The barrel has a bigger column
> in
> > >it's part, than the hose. So the weight of the water column is
> GREATLY
> > >larger than the one in the hose going to the top. Less water - less
> > >weight, right?
> >
> > Nope. When we speak of a column in this context, the column has the
> > same area as the hose through which you're pumping fluid. If you
> > wanted to know the pressure in pounds per square inch, you'd consider
> > an imaginary coulumn with a cross-sectional area of 1 square inch.
> >
> > The volume of fluid outside the column doesn't matter.
> >
> > Consider this:
> >
> > If you submerge yourself one foot under water in your swimming pool,
> > you're subject to the same pressure as if you were submerged one foot
> > under water in Lake Superior, even though the volume of Lake Superior
> > is a gazillion times larger than your swimming pool (gazillion being a
> > highly technical term used for these sorts of comparisons).
>
> If you submerge yourself a foot under water in Lake Superior, you had
> better be related to the polar bear. ;-)
>
>
> Ray Drouillard
And the pressure might go up a bit as density does go up a small
amount for colder water. Densist at 4 degree (F or C?) IIRC from 50
years ago.
Harry K
> "Tom Quackenbush" <tquackenbogusinfo@kingcon.com> wrote in message
> news:pmq9q0l4sjckqakm5b9sma5mdlptajk6fp@4ax.com...
> > Jeepers wrote:
> > <snip>
> >
> > >O.K. my lame-*** attempt at physics argument:
> > >
> > >Isn't part of the column the barrel? The barrel has a bigger column
> in
> > >it's part, than the hose. So the weight of the water column is
> GREATLY
> > >larger than the one in the hose going to the top. Less water - less
> > >weight, right?
> >
> > Nope. When we speak of a column in this context, the column has the
> > same area as the hose through which you're pumping fluid. If you
> > wanted to know the pressure in pounds per square inch, you'd consider
> > an imaginary coulumn with a cross-sectional area of 1 square inch.
> >
> > The volume of fluid outside the column doesn't matter.
> >
> > Consider this:
> >
> > If you submerge yourself one foot under water in your swimming pool,
> > you're subject to the same pressure as if you were submerged one foot
> > under water in Lake Superior, even though the volume of Lake Superior
> > is a gazillion times larger than your swimming pool (gazillion being a
> > highly technical term used for these sorts of comparisons).
>
> If you submerge yourself a foot under water in Lake Superior, you had
> better be related to the polar bear. ;-)
>
>
> Ray Drouillard
And the pressure might go up a bit as density does go up a small
amount for colder water. Densist at 4 degree (F or C?) IIRC from 50
years ago.
Harry K
11-24-2004, 11:02 PM
#155
Guest
Posts: n/a
Re: Physics/hydraulics of water and barrel
>
>
> Nope. That only matters if you want to calculate how many linear
> feet of water moving up the hose it will take to make the depth
> inside the barrel rise by one inch.
It also matters if you want to know whether pushing on the pump handle
is going to move water, or bend the handle. If you're talking about
PSI, the cross-section of the hose doesn't matter, only the vertical head.
If you're talking about total force working against the pump, then
you device the volume of water displaced by each stroke by the
length of the stroke, and multiply the result by the pressure.
In no case does using a smaller hose make things easier.
--Goedjn
>
> Nope. That only matters if you want to calculate how many linear
> feet of water moving up the hose it will take to make the depth
> inside the barrel rise by one inch.
It also matters if you want to know whether pushing on the pump handle
is going to move water, or bend the handle. If you're talking about
PSI, the cross-section of the hose doesn't matter, only the vertical head.
If you're talking about total force working against the pump, then
you device the volume of water displaced by each stroke by the
length of the stroke, and multiply the result by the pressure.
In no case does using a smaller hose make things easier.
--Goedjn
11-24-2004, 11:02 PM
#156
Guest
Posts: n/a
Re: Physics/hydraulics of water and barrel
>
>
> Nope. That only matters if you want to calculate how many linear
> feet of water moving up the hose it will take to make the depth
> inside the barrel rise by one inch.
It also matters if you want to know whether pushing on the pump handle
is going to move water, or bend the handle. If you're talking about
PSI, the cross-section of the hose doesn't matter, only the vertical head.
If you're talking about total force working against the pump, then
you device the volume of water displaced by each stroke by the
length of the stroke, and multiply the result by the pressure.
In no case does using a smaller hose make things easier.
--Goedjn
>
> Nope. That only matters if you want to calculate how many linear
> feet of water moving up the hose it will take to make the depth
> inside the barrel rise by one inch.
It also matters if you want to know whether pushing on the pump handle
is going to move water, or bend the handle. If you're talking about
PSI, the cross-section of the hose doesn't matter, only the vertical head.
If you're talking about total force working against the pump, then
you device the volume of water displaced by each stroke by the
length of the stroke, and multiply the result by the pressure.
In no case does using a smaller hose make things easier.
--Goedjn
11-24-2004, 11:02 PM
#157
Guest
Posts: n/a
Re: Physics/hydraulics of water and barrel
>
>
> Nope. That only matters if you want to calculate how many linear
> feet of water moving up the hose it will take to make the depth
> inside the barrel rise by one inch.
It also matters if you want to know whether pushing on the pump handle
is going to move water, or bend the handle. If you're talking about
PSI, the cross-section of the hose doesn't matter, only the vertical head.
If you're talking about total force working against the pump, then
you device the volume of water displaced by each stroke by the
length of the stroke, and multiply the result by the pressure.
In no case does using a smaller hose make things easier.
--Goedjn
>
> Nope. That only matters if you want to calculate how many linear
> feet of water moving up the hose it will take to make the depth
> inside the barrel rise by one inch.
It also matters if you want to know whether pushing on the pump handle
is going to move water, or bend the handle. If you're talking about
PSI, the cross-section of the hose doesn't matter, only the vertical head.
If you're talking about total force working against the pump, then
you device the volume of water displaced by each stroke by the
length of the stroke, and multiply the result by the pressure.
In no case does using a smaller hose make things easier.
--Goedjn
11-24-2004, 11:06 PM
#158
Guest
Posts: n/a
Re: Physics/hydraulics of water and barrel
> I'm with you on this one -
> The barrel has a lager cross-section than the hose. Much like the
> pistons in a kiddie-toy-simple two-ram hydraulic system - Big piston
> pushes on fluid, sending it throrugh the lines to wherever the work
Well, it's a lot like the pistons in a kiddie-toy, except without the
piston part..
> The barrel has a lager cross-section than the hose. Much like the
> pistons in a kiddie-toy-simple two-ram hydraulic system - Big piston
> pushes on fluid, sending it throrugh the lines to wherever the work
Well, it's a lot like the pistons in a kiddie-toy, except without the
piston part..
11-24-2004, 11:06 PM
#159
Guest
Posts: n/a
Re: Physics/hydraulics of water and barrel
> I'm with you on this one -
> The barrel has a lager cross-section than the hose. Much like the
> pistons in a kiddie-toy-simple two-ram hydraulic system - Big piston
> pushes on fluid, sending it throrugh the lines to wherever the work
Well, it's a lot like the pistons in a kiddie-toy, except without the
piston part..
> The barrel has a lager cross-section than the hose. Much like the
> pistons in a kiddie-toy-simple two-ram hydraulic system - Big piston
> pushes on fluid, sending it throrugh the lines to wherever the work
Well, it's a lot like the pistons in a kiddie-toy, except without the
piston part..
11-24-2004, 11:06 PM
#160
Guest
Posts: n/a
Re: Physics/hydraulics of water and barrel
> I'm with you on this one -
> The barrel has a lager cross-section than the hose. Much like the
> pistons in a kiddie-toy-simple two-ram hydraulic system - Big piston
> pushes on fluid, sending it throrugh the lines to wherever the work
Well, it's a lot like the pistons in a kiddie-toy, except without the
piston part..
> The barrel has a lager cross-section than the hose. Much like the
> pistons in a kiddie-toy-simple two-ram hydraulic system - Big piston
> pushes on fluid, sending it throrugh the lines to wherever the work
Well, it's a lot like the pistons in a kiddie-toy, except without the
piston part..