Well, everything is in the title...
Take any drink that contains a dissolved gas, generally CO2. Shake the bottle, and the pressure rises.
Any reasonable explanation?
It doesn't
http://www.powerset.com/explore/go/Take-an...-pressure-rises.
QUOTE
It is commonly said that shaking a carbonated beverage will cause large amounts of foam to erupt upon opening, and it is often believed that shaking a bottle containing a carbonated beverage will cause the pressure inside to rise. In fact, when a pressure gauge is attached to a pressurized bottle of a carbonated beverage, it is found that the pressure within does not increase. It is instead the formation of tiny bubbles from the agitation that causes the foam; upon opening, the size of the bubbles will rapidly increase due to the reduction in pressure, resulting in excessive foaming.
http://www.powerset.com/explore/go/Take-an...-pressure-rises.
This thread reminds me of a question that I've had(and never asked) for 30 years. 30 years ago, when I was 16, I got my first job pumping gas. One day, a man pulled up in his Jaguar, got out of his car and as he was heading inside the building, he told me to "filler' up". Well, I couldn't find his gas tank. I looked on the left side of the car, the right side of the car and tried to look behind his back license plate(some cars had access to their gas tanks that way back then). After I circled his car a couple of times, the man came out and showed me where his gas tank was located. There was something that resembled a suitcase latch on top of his car, on the side of his trunk. When he lifted up the latch, I was able to insert the gas pump. Well, he went back inside and I filled his tank. When I removed the gas pump, the gasoline came shooting straight up in the air(almost his whole tank emptied) like water out of the spout of a whale. I got totally doused with gasoline as did his car. We actually had to push his car off to the side and give him a carwash. Anyhow, what exactly caused the gas to shoot up in the air like that? I've always assumed that it was some sort of pressure within the tank...can anyone tell me the actual explanation? Just curious. Thanks.
Off-topic, but maybe similar.
If you shake a bottle of Scotch Whiskey and then thump it, the sound is deadened, as opposed to the sound a thump gives when the bottle hasn't been shaken.
Now that someone may be looking for my invisible ink, I have to play harder!
I hate to shake Scotch, so I never pursued the thought. Anyone?
Or not. I just like to accumulate posts...
If you shake a bottle of Scotch Whiskey and then thump it, the sound is deadened, as opposed to the sound a thump gives when the bottle hasn't been shaken.
Now that someone may be looking for my invisible ink, I have to play harder!
I hate to shake Scotch, so I never pursued the thought. Anyone?
Or not. I just like to accumulate posts...
QUOTE (newguy+May 28 2008, 01:48 AM)
This thread reminds me of a question that I've had(and never asked) for 30 years. 30 years ago, when I was 16, I got my first job pumping gas. One day, a man pulled up in his Jaguar, got out of his car and as he was heading inside the building, he told me to "filler' up". Well, I couldn't find his gas tank. I looked on the left side of the car, the right side of the car and tried to look behind his back license plate(some cars had access to their gas tanks that way back then). After I circled his car a couple of times, the man came out and showed me where his gas tank was located. There was something that resembled a suitcase latch on top of his car, on the side of his trunk. When he lifted up the latch, I was able to insert the gas pump. Well, he went back inside and I filled his tank. When I removed the gas pump, the gasoline came shooting straight up in the air(almost his whole tank emptied) like water out of the spout of a whale. I got totally doused with gasoline as did his car. We actually had to push his car off to the side and give him a carwash. Anyhow, what exactly caused the gas to shoot up in the air like that? I've always assumed that it was some sort of pressure within the tank...can anyone tell me the actual explanation? Just curious. Thanks.
How tight was the seal of the hose nozzle in the hole?
and did you have to hold it down to keep it from coming out?
Although I would think the pump should have shut off if there was no way for the air to escape and you were just compressing it.
How tight was the seal of the hose nozzle in the hole?
and did you have to hold it down to keep it from coming out?
Although I would think the pump should have shut off if there was no way for the air to escape and you were just compressing it.
QUOTE (buttershug+)
How tight was the seal of the hose nozzle in the hole?
and did you have to hold it down to keep it from coming out?
Although I would think the pump should have shut off if there was no way for the air to escape and you were just compressing it.
buttershug: Like I said, it was 30 years ago. To my recollection, the pump was in tight and I did NOT have to hold it down. As far as the pump shutting off is concerned, I have no way of knowing if the tank was actually full or not. The pump did shut off by itself at some point and I pumped a little more to round it off to the nearest dollar amount. All I know is that a lot of gas came out, shooting straight up in the air...enough to totally douse me and the man's car. I had always assumed that this had something to do with pressure built up in the man's tank and I always likened it in my mind to the pressure within a soda bottle. However, after reading xtrmn8r's response, I'm not sure.
and did you have to hold it down to keep it from coming out?
Although I would think the pump should have shut off if there was no way for the air to escape and you were just compressing it.
buttershug: Like I said, it was 30 years ago. To my recollection, the pump was in tight and I did NOT have to hold it down. As far as the pump shutting off is concerned, I have no way of knowing if the tank was actually full or not. The pump did shut off by itself at some point and I pumped a little more to round it off to the nearest dollar amount. All I know is that a lot of gas came out, shooting straight up in the air...enough to totally douse me and the man's car. I had always assumed that this had something to do with pressure built up in the man's tank and I always likened it in my mind to the pressure within a soda bottle. However, after reading xtrmn8r's response, I'm not sure.
The only way that could happen is if the air in the tank being displaced by the gas, had nowhere to go.The pump would have shut off because the pressure triggered the valve. When you removed the pump it belched. Good thing you weren't smoking. 
It is likely the Jag, like many Brit cars of the era, had a strange-shaped or multi-compartment fuel tank (I had a Lotus that had two independent tanks --- I used two gas pumps simultaneously ). So it could be that there came to be a big pressure diff somewhere in the system and it got relieved via transfer lines or just the shape of the thing.
). So it could be that there came to be a big pressure diff somewhere in the system and it got relieved via transfer lines or just the shape of the thing.
QUOTE (xtrmn8r+)
The only way that could happen is if the air in the tank being displaced by the gas, had nowhere to go.The pump would have shut off because the pressure triggered the valve. When you removed the pump it belched. Good thing you weren't smoking.
xtrmn8r: That's pretty much what I've guessed all along, but what exactly would have caused the pressure in the tank to make the air want to come out(I hope that made sense)? That's what I'm really asking...I think.
Anyhow, BELIEVE ME, I thought about the "smoking" thing when it happened. I've also recently thought how fortunate I was that some of the forum members here weren't smoking nearby...I might have "accidentally" had some ashes flicked my way. 
Only kidding...well, sort of. Thanks for your input.
xtrmn8r: That's pretty much what I've guessed all along, but what exactly would have caused the pressure in the tank to make the air want to come out(I hope that made sense)? That's what I'm really asking...I think.
Anyhow, BELIEVE ME, I thought about the "smoking" thing when it happened. I've also recently thought how fortunate I was that some of the forum members here weren't smoking nearby...I might have "accidentally" had some ashes flicked my way. Only kidding...well, sort of. Thanks for your input.QUOTE (NoCleverName+)
It is likely the Jag, like many Brit cars of the era, had a strange-shaped or multi-compartment fuel tank (I had a Lotus that had two independent tanks --- I used two gas pumps simultaneously). So it could be that there came to be a big pressure diff somewhere in the system and it got relieved via transfer lines or just the shape of the thing.
NoCleverName: I also previously considered the shape of the gas tank, since it was accessed from above as opposed to the usual side access. In fact, after posting on this thread last night, I spent about 15 minutes or so doing a Google search on "Jaguar gas tanks" and similar word structures trying to see if anyone else had ever encountered what I described. My search came up empty so far. Anyhow, thanks for your comments as well.
P.S. While I'm at it, I might as well ask one other unrelated question. Years ago, when I still lived at home with my mother, we had a continual disagreement regarding batteries. Whenever I purchased batteries, whether AA, C or D, I would put them in a little drawer in one of our kitchen cabinets so I would know where to find them when I needed them. Well, if you know how mothers can be, the batteries were NEVER in the drawer when I looked for them. No, rather, my mother ALWAYS(and I mean ALWAYS, we argued about this FOR YEARS) took the batteries out of the drawer and placed them in the REFRIGERATOR, of all places. Someone had once told her(probably a forum member who wanted to destroy my batteries ) that batteries lasted longer if they were stored in a cold place. I could be wrong(I'll apologize to my mother if I am), but that never made any sense to me whatsoever. Aside from the fact that I've never seen batteries kept in a cold area in stores, I'm also aware of what cold weather has done to different car batteries of mine over the years(I've had my fair share of "jump starts"). Anyhow, can any of you finally put this to rest for me? Like I said, I'll be glad to apologize to my mother if I've been wrong for all these years. Thanks.
P.P.S. In case any of you are wondering why I didn't just find another "hiding place" for my batteries...It wouldn't have mattered...my mother(like most mothers, I suspect) had/has a "sixth sense"...she would have found them, anyway.
NoCleverName: I also previously considered the shape of the gas tank, since it was accessed from above as opposed to the usual side access. In fact, after posting on this thread last night, I spent about 15 minutes or so doing a Google search on "Jaguar gas tanks" and similar word structures trying to see if anyone else had ever encountered what I described. My search came up empty so far. Anyhow, thanks for your comments as well.
P.S. While I'm at it, I might as well ask one other unrelated question. Years ago, when I still lived at home with my mother, we had a continual disagreement regarding batteries. Whenever I purchased batteries, whether AA, C or D, I would put them in a little drawer in one of our kitchen cabinets so I would know where to find them when I needed them. Well, if you know how mothers can be, the batteries were NEVER in the drawer when I looked for them. No, rather, my mother ALWAYS(and I mean ALWAYS, we argued about this FOR YEARS) took the batteries out of the drawer and placed them in the REFRIGERATOR, of all places. Someone had once told her(probably a forum member who wanted to destroy my batteries
) that batteries lasted longer if they were stored in a cold place. I could be wrong(I'll apologize to my mother if I am), but that never made any sense to me whatsoever. Aside from the fact that I've never seen batteries kept in a cold area in stores, I'm also aware of what cold weather has done to different car batteries of mine over the years(I've had my fair share of "jump starts"). Anyhow, can any of you finally put this to rest for me? Like I said, I'll be glad to apologize to my mother if I've been wrong for all these years. Thanks.P.P.S. In case any of you are wondering why I didn't just find another "hiding place" for my batteries...It wouldn't have mattered...my mother(like most mothers, I suspect) had/has a "sixth sense"...she would have found them, anyway.
I reckon Space must expand at the speed of coca-cola light!
Or else it's something like this...
http://en.wikipedia.org/wiki/Joule-Thomson_effect
g.
Or else it's something like this...
http://en.wikipedia.org/wiki/Joule-Thomson_effect
g.
newguy,
I think buttershug has it right
I think buttershug has it right
Although I would think the pump should have shut off if there was no way for the air to escape and you were just compressing it.
You don't gain much for your effort.
You don't gain much for your effort.
Battery life can be extended by storing the batteries at a low temperature, as in a refrigerator or freezer, because the chemical reactions in the batteries are slower. Such storage can extend the life of alkaline batteries by ~5%; while the charge of rechargeable batteries can be extended from a few days up to several months. In order to reach their maximum voltage, batteries must be returned to room temperature; therefore, alkaline battery manufacturers like Duracell do not recommend refrigerating or freezing batteries.
Does anyone know if I"m also out to lunch with my theory that shaking the pop causes CO2 to come out of solution?
I mean the more CO2 you have that is not dissolved the higher the pressure in a closed container.
I would say you are NOT out to lunch.....just a hunch..
When you shake the container, after it has been sitting for a while, the pressure will increase as more surface area of the liquid is exposed. The agitation facilitates exchange of CO2 into a gaseous state. When again at rest the CO2 will naturally reabsorb into the solution lessening the pressure until some equilibrium is reached.
Don't take my word for it though!
mr_ homm mentioned this in his post a while back...
See this. This is called arguing for the sake of arguing. Not because of the info, but because of the person.
Take a new bottle of pop (soda). Look inside and you will see very few bubbles (if any). Crack open the bottle and you will see bubble appear withing the pop. Open it until there is no his and you will see bubbles form and rise to the surface. Close the bottle. Over time the bubbles that form and rise will build up a pressure and more bubbles will stop forming when an equilibrium is obtained.
See this. This is called arguing for the sake of arguing. Not because of the info, but because of the person.
Take a new bottle of pop (soda). Look inside and you will see very few bubbles (if any). Crack open the bottle and you will see bubble appear withing the pop. Open it until there is no his and you will see bubbles form and rise to the surface. Close the bottle. Over time the bubbles that form and rise will build up a pressure and more bubbles will stop forming when an equilibrium is obtained.
So light needs to accelerate to get up to speed but gas dissolves instantly?
Where was the use of the word "instantly"? I believe I said "eventually" at one point which implies a passing of time.
The bubbles were once dissolved gas. That is what I meant. An increase in bubble results in a decrease in dissolved gas provided that the gas that comprises the bubble once was the dissolved gas.
Bad wording on my part. Sorry.
The bubbles were once dissolved gas. That is what I meant. An increase in bubble results in a decrease in dissolved gas provided that the gas that comprises the bubble once was the dissolved gas.
Bad wording on my part. Sorry.
Get a glass of water. There is dissolved CO2 in it.
There is also atmospheric pressure being applied onto it. We have a machine for testing the contamination of hydraulic oil taken from aircrafts. Before the machine can be used on the oil, the oil must first be put into a chamber where it undergoes a decrease in atmospheric pressure. This forces dissolved gas (that can interfere with the testing) to form bubbles and rise to the surface.
QUOTE
..but what exactly would have caused the pressure in the tank to make the air want to come out..
I think buttershug has it right
QUOTE (->
| QUOTE |
| ..but what exactly would have caused the pressure in the tank to make the air want to come out.. |
I think buttershug has it right
Although I would think the pump should have shut off if there was no way for the air to escape and you were just compressing it.
QUOTE
...that batteries lasted longer if they were stored in a cold place.
You don't gain much for your effort.
QUOTE (->
| QUOTE |
| ...that batteries lasted longer if they were stored in a cold place. |
You don't gain much for your effort.
Battery life can be extended by storing the batteries at a low temperature, as in a refrigerator or freezer, because the chemical reactions in the batteries are slower. Such storage can extend the life of alkaline batteries by ~5%; while the charge of rechargeable batteries can be extended from a few days up to several months. In order to reach their maximum voltage, batteries must be returned to room temperature; therefore, alkaline battery manufacturers like Duracell do not recommend refrigerating or freezing batteries.
xtrmn8r: Thanks for the battery info. I went to the link and also saw this:
Life of primary batteries
Even if never taken out of the original package, disposable (or "primary") batteries can lose 8 to 20 percent of their original charge every year at a temperature of about 20°–30°C.[65] This is known as the "self discharge" rate and is due to non-current-producing "side" chemical reactions, which occur within the cell even if no load is applied to it. The rate of the side reactions is reduced if the batteries are stored at low temperature, although some batteries can be damaged by freezing. High or low temperatures may reduce battery performance. This will affect the initial voltage of the battery. For an AA alkaline battery this initial voltage is approximately normally distributed around 1.6 volts.
It seems that colder temperatures can have either a "positive" or "negative" effect on batteries...no pun intended. Anyhow, thanks again for the input.
Life of primary batteries
Even if never taken out of the original package, disposable (or "primary") batteries can lose 8 to 20 percent of their original charge every year at a temperature of about 20°–30°C.[65] This is known as the "self discharge" rate and is due to non-current-producing "side" chemical reactions, which occur within the cell even if no load is applied to it. The rate of the side reactions is reduced if the batteries are stored at low temperature, although some batteries can be damaged by freezing. High or low temperatures may reduce battery performance. This will affect the initial voltage of the battery. For an AA alkaline battery this initial voltage is approximately normally distributed around 1.6 volts.
It seems that colder temperatures can have either a "positive" or "negative" effect on batteries...no pun intended. Anyhow, thanks again for the input.
Back to the original question.
Shaking a bottle of pop (as stated) will not increase the pressure within the bottle. When shaken the liquid will place small bubbles of compressed gas into the liquid (which upon unsealing, these bubbles expand causing the eruption) but this doesn't take away from the pressure in any way since the whole thing is a sealed unit and the small bubbles are of compressed gas each exerting a small pressure within the . So even if the gas was taken from the pocket above the liquid, it is merely relocated within the confinement.
Shaking a bottle of pop (as stated) will not increase the pressure within the bottle. When shaken the liquid will place small bubbles of compressed gas into the liquid (which upon unsealing, these bubbles expand causing the eruption) but this doesn't take away from the pressure in any way since the whole thing is a sealed unit and the small bubbles are of compressed gas each exerting a small pressure within the . So even if the gas was taken from the pocket above the liquid, it is merely relocated within the confinement.
I'm not sure I believe that there is NO pressure increase when you shake up a soda drink. For instance, from personal experience, you can squeeze a plastic bottle of soda which has been sitting still for a while, shake it, and squeeze it again, and you can FEEL that it is firmer. My guess here is that the plastic bottles are not altogether impervious to vapor, and so the vapor in the gas phase diffuses out slowly, which leaves the pressure in the bottle at atmospheric pressure, or close to it. Meanwhile, the dissolved gas in the liquid phase becomes supersaturated because its vapor pressure is now higher than the pressure in the bottle, but it does not immediately change phase. This would be similar to supercooled water not immediately forming ice. The contents of the bottle would attain a metastable state, in which a disturbance (such as shaking) would cause the dissolved gas to evaporate and restor equilibrium.
The explanation (that soon after shaking, there are many small bubbles floating in the liquid, which rapidly expand when the bottle is opened, and carry a jet of liquid out with them) sounds like a good reason for the FOAM, doesn't really address the pressure change. In other words, I think that the presure increase is real (though small) but is unrelated to the jetting effect. A further personal experience is that you can measure the liquid level in a plastic soda bottle before and after shaking, and you will find that it is slightly lower after shaking. This indicates to me that the bottle has expanded slightly, which is an objective indication of higher pressure. Of course, it may be true that for CANS, the permeability is so low that the gas does not diffuse out, so my explanation may only apply to plastic bottles.
As to the gasoline tank question, since I don't know the internal configuration of the gasoline tank, this is just a guess: Suppose that some (very foolish) engineer decided that the tank needed a tube leading from the external opening down to near the bottom of the tank. (I can't think of a single reason why anyone would do this, but it would produce a nice gasoline jet, so perhaps this is the way the tank was made.) In order to fill the tank at all with this arrangement, you would need some kind of vent at the top, since the tank would tend to trap air, so suppose there was such a vent (another bad idea) and that it was clogged. Then all the trapped air in the tank would pressurize when you tried to fill it, and when you removed the nozzle, the pressure would expel pure liquid gasoline straight up the fill spout. With a tank like this, a pressure P will, when released, produce a jet that rises to a height given by P = dgh, where d is the density of gasoline. Therefore, h = P/dg. Since d = about 700kg/m^3 and g is roughly 10N/kg, this gives h = P/(7000N/m^3). Even a pressure of 0.1atmoshere = 10000N/m^2 would shoot gasoline to a height of about 1.4m. This is certainly high enough to get all over the entire car and the person pumping the gas. While this would explain the geyser, I can't believe that anyone would really design a tank like that.
--Stuart Anderson
The explanation (that soon after shaking, there are many small bubbles floating in the liquid, which rapidly expand when the bottle is opened, and carry a jet of liquid out with them) sounds like a good reason for the FOAM, doesn't really address the pressure change. In other words, I think that the presure increase is real (though small) but is unrelated to the jetting effect. A further personal experience is that you can measure the liquid level in a plastic soda bottle before and after shaking, and you will find that it is slightly lower after shaking. This indicates to me that the bottle has expanded slightly, which is an objective indication of higher pressure. Of course, it may be true that for CANS, the permeability is so low that the gas does not diffuse out, so my explanation may only apply to plastic bottles.
As to the gasoline tank question, since I don't know the internal configuration of the gasoline tank, this is just a guess: Suppose that some (very foolish) engineer decided that the tank needed a tube leading from the external opening down to near the bottom of the tank. (I can't think of a single reason why anyone would do this, but it would produce a nice gasoline jet, so perhaps this is the way the tank was made.) In order to fill the tank at all with this arrangement, you would need some kind of vent at the top, since the tank would tend to trap air, so suppose there was such a vent (another bad idea) and that it was clogged. Then all the trapped air in the tank would pressurize when you tried to fill it, and when you removed the nozzle, the pressure would expel pure liquid gasoline straight up the fill spout. With a tank like this, a pressure P will, when released, produce a jet that rises to a height given by P = dgh, where d is the density of gasoline. Therefore, h = P/dg. Since d = about 700kg/m^3 and g is roughly 10N/kg, this gives h = P/(7000N/m^3). Even a pressure of 0.1atmoshere = 10000N/m^2 would shoot gasoline to a height of about 1.4m. This is certainly high enough to get all over the entire car and the person pumping the gas. While this would explain the geyser, I can't believe that anyone would really design a tank like that.
--Stuart Anderson
mr_ homm,
I would if it were an British made car
QUOTE
While this would explain the geyser, I can't believe that anyone would really design a tank like that.
I would if it were an British made car
Liquids disolve gasses.
Sodapop has disolved Co2. Disolved CO2 does not add to the pressure.
You shake the can or bottle and it makes the CO2 come out of the solution.
It now adds to the pressure since it is not longer disolved.
Slamming the can down on a hard surface will be more effective. I've seen cans pop open whne that was done to them.
And remember solubilty of a gas in liquid is inverse to the temperature.
Sodapop has disolved Co2. Disolved CO2 does not add to the pressure.
You shake the can or bottle and it makes the CO2 come out of the solution.
It now adds to the pressure since it is not longer disolved.
Slamming the can down on a hard surface will be more effective. I've seen cans pop open whne that was done to them.
And remember solubilty of a gas in liquid is inverse to the temperature.
..just my thoughts...
Filling a gas tank creates turbulence. Some pumps inject the petrol at higher velocities. As the liquid is filling the tank, petrol and air are sloshing about. Like a boat can lose buoyancy and sink, the sensor that shuts off the pump is no longer responsive due this air/petrol mixture and thus allows the tank to rise to a level where the "aerated" petro is literally blown out the inlet as the delayed shutoff mechanism miscalculates the actual petrol level in the tank. This occurs too when "topping off" a tank....the petrol is already up to the filling tube and a momentary injection of the petrol will cause a "blowout" before the sensor can again shut off the supply.
Understanding that this happened many years ago, I think the interpretation of what actually happened may have been slightly distorted, or mis-remembered.
Filling a gas tank creates turbulence. Some pumps inject the petrol at higher velocities. As the liquid is filling the tank, petrol and air are sloshing about. Like a boat can lose buoyancy and sink, the sensor that shuts off the pump is no longer responsive due this air/petrol mixture and thus allows the tank to rise to a level where the "aerated" petro is literally blown out the inlet as the delayed shutoff mechanism miscalculates the actual petrol level in the tank. This occurs too when "topping off" a tank....the petrol is already up to the filling tube and a momentary injection of the petrol will cause a "blowout" before the sensor can again shut off the supply.
Understanding that this happened many years ago, I think the interpretation of what actually happened may have been slightly distorted, or mis-remembered.
As far as I know the sensor is simply a pressure detector, not any kind of level detector.
QUOTE (buttershug+May 29 2008, 07:06 AM)
As far as I know the sensor is simply a pressure detector, not any kind of level detector.
right... the vacuum that is increased to shut off the pump does not materialize (in time) because of the aerated fuel and thus overfills.
...and since the filler tube was probably longer than usual, being on top of the trunk, the aerated fuel went shooting up the tube and out while the sensor was still looking for an increase of vacuum.
right... the vacuum that is increased to shut off the pump does not materialize (in time) because of the aerated fuel and thus overfills.
...and since the filler tube was probably longer than usual, being on top of the trunk, the aerated fuel went shooting up the tube and out while the sensor was still looking for an increase of vacuum.
QUOTE (Bloy+May 29 2008, 01:39 PM)
right... the vacuum that is increased to shut off the pump does not materialize (in time) because of the aerated fuel and thus overfills.
...and since the filler tube was probably longer than usual, being on top of the trunk, the aerated fuel went shooting up the tube and out while the sensor was still looking for an increase of vacuum.
Increase of vaccuum?
I was thinking of positive pressure.
We have a selective solder machine at work. The way it detects the solder level is by using the pressurized nitrogen. When the solder is at the proper level it blocks the level dection nozzle which means the nitrogen is at full pressure. When the solder level drops the nitrogen can escape and thereby lowers the pressure and sets off the low level detection.
I was imagineing something similar with gas pumps, when the nozzle is clear there is little back pressure. When the nozzle is blocked by a full tank there is more back pressure and the pump shuts off.
...and since the filler tube was probably longer than usual, being on top of the trunk, the aerated fuel went shooting up the tube and out while the sensor was still looking for an increase of vacuum.
Increase of vaccuum?
I was thinking of positive pressure.
We have a selective solder machine at work. The way it detects the solder level is by using the pressurized nitrogen. When the solder is at the proper level it blocks the level dection nozzle which means the nitrogen is at full pressure. When the solder level drops the nitrogen can escape and thereby lowers the pressure and sets off the low level detection.
I was imagineing something similar with gas pumps, when the nozzle is clear there is little back pressure. When the nozzle is blocked by a full tank there is more back pressure and the pump shuts off.
How does a gas pump shut off automatically when the gas tank is full?
And he said this was 30 years ago... we were a lot more primitive back then. Gas was still under a dollar a gallon!
And he said this was 30 years ago... we were a lot more primitive back then. Gas was still under a dollar a gallon!
...a cross section view of the sensing mechanism of a gas pump nozzle:
http://www.wonderquest.com/figure-gas-nozzle.htm
I wouldn't say there aren't many other designs for shutting off fuel flow....this is just a "typical" fuel nozzle.
http://www.wonderquest.com/figure-gas-nozzle.htm
I wouldn't say there aren't many other designs for shutting off fuel flow....this is just a "typical" fuel nozzle.
QUOTE (Bloy+May 29 2008, 03:34 PM)
...a cross section view of the sensing mechanism of a gas pump nozzle:
http://www.wonderquest.com/figure-gas-nozzle.htm
I wouldn't say there aren't many other designs for shutting off fuel flow....this is just a "typical" fuel nozzle.
Next time I fill up I will have to look for that hole.
Does anyone know if I"m also out to lunch with my theory that shaking the pop causes CO2 to come out of solution?
I mean the more CO2 you have that is not dissolved the higher the pressure in a closed container.
http://www.wonderquest.com/figure-gas-nozzle.htm
I wouldn't say there aren't many other designs for shutting off fuel flow....this is just a "typical" fuel nozzle.
Next time I fill up I will have to look for that hole.
Does anyone know if I"m also out to lunch with my theory that shaking the pop causes CO2 to come out of solution?
I mean the more CO2 you have that is not dissolved the higher the pressure in a closed container.
QUOTE (buttershug+May 29 2008, 09:58 AM)
Does anyone know if I"m also out to lunch with my theory that shaking the pop causes CO2 to come out of solution?
I mean the more CO2 you have that is not dissolved the higher the pressure in a closed container.
I would say you are NOT out to lunch.....just a hunch..
When you shake the container, after it has been sitting for a while, the pressure will increase as more surface area of the liquid is exposed. The agitation facilitates exchange of CO2 into a gaseous state. When again at rest the CO2 will naturally reabsorb into the solution lessening the pressure until some equilibrium is reached.
Don't take my word for it though!
mr_ homm mentioned this in his post a while back...
All: Once again, I thank everybody for their contributions in attempting to answer my question. I found this website a few moments ago...I think this might effectively answer my question. Any future comments are welcome. Thanks.
http://www.jagbits.com/29whooshing.html
29. "Whooshing" Fuel Tanks in Series III XJ6 Jaguars
Jaguar Parts Technical Information
The Series III XJ6 Jaguar has a fuel vapor recovery system, which captures excess fuel vapors inside the charcoal canister located in the front right fender. Sometimes this system gets clogged or a pressure valve malfunctions, leading to a substantial vacuum in the fuel tank. The most noticeable symptom is a whooshing sound when you open the fuel tank filler caps. This whooshing sound is bad news. The vacuum builds up in the tank until the sides of the tank suck in a little. Then, when the filler caps are opened, the fuel tank expands back out. You can sometimes hear the tank popping back into shape. Do this a lot and the tank will crack from the flexing and start to leak. The usual suspect is a little valve right next to the charcoal canister, inline with a rubber hose leading to the canister. When that valve fails, the vacuum builds up. The only fix for this is to replace the valve. Fortunately, this "pressure valve", part number CAC3101 is pretty inexpensive at around $30. Ok, for a cheap little plastic part that's pretty darn expensive, but it's certainly cheaper than $470 for a new tank!
http://www.jagbits.com/29whooshing.html
29. "Whooshing" Fuel Tanks in Series III XJ6 Jaguars
Jaguar Parts Technical Information
The Series III XJ6 Jaguar has a fuel vapor recovery system, which captures excess fuel vapors inside the charcoal canister located in the front right fender. Sometimes this system gets clogged or a pressure valve malfunctions, leading to a substantial vacuum in the fuel tank. The most noticeable symptom is a whooshing sound when you open the fuel tank filler caps. This whooshing sound is bad news. The vacuum builds up in the tank until the sides of the tank suck in a little. Then, when the filler caps are opened, the fuel tank expands back out. You can sometimes hear the tank popping back into shape. Do this a lot and the tank will crack from the flexing and start to leak. The usual suspect is a little valve right next to the charcoal canister, inline with a rubber hose leading to the canister. When that valve fails, the vacuum builds up. The only fix for this is to replace the valve. Fortunately, this "pressure valve", part number CAC3101 is pretty inexpensive at around $30. Ok, for a cheap little plastic part that's pretty darn expensive, but it's certainly cheaper than $470 for a new tank!
Just a though for the CO2. The liquid can only dissolve so much gas. This depends on the pressure that is applied to the liquid. The higher the pressure, the more gas that can be dissolved into it. Although there is no doubt an ultimate limit there.
So if the bubbles formed are the dissolved gas then there still shouldn't be an increase in pressure because an increase in gaseous bubbles is a direct result of a decrease in dissolved gas. If the amount of gas dissolved is a result of being under pressure then it should apply an equal and opposite pressure back. Since it is compressed gas that is applying the pressure if the pressure being applied back (equal and opposite and what not) is not equal then one of two things should happen.
1. The pressure being applied by the external gas is greater and will become dissolved into the fluid until an equilibrium is obtained.
2. The pressure being applied back by the dissolved gas is greater and will form bubbles which will eventually make their way to the surface adding to the external gas. Again forming an equilibrium.
Again, just a thought.
So if the bubbles formed are the dissolved gas then there still shouldn't be an increase in pressure because an increase in gaseous bubbles is a direct result of a decrease in dissolved gas. If the amount of gas dissolved is a result of being under pressure then it should apply an equal and opposite pressure back. Since it is compressed gas that is applying the pressure if the pressure being applied back (equal and opposite and what not) is not equal then one of two things should happen.
1. The pressure being applied by the external gas is greater and will become dissolved into the fluid until an equilibrium is obtained.
2. The pressure being applied back by the dissolved gas is greater and will form bubbles which will eventually make their way to the surface adding to the external gas. Again forming an equilibrium.
Again, just a thought.
So light needs to accelerate to get up to speed but gas dissolves instantly?
And your number 2 doesn't make sense.
It doesn't matter where the bubbles are. They can be spread throughout the pop or at the top. And I don't believe the dissolved gas adds any pressure, it's only when it comes out of solution to form bubbles that it contributes to the pressure.
I want to make sure I understand you.
Are you thinking that the bubbles are the dissolved gas?
Because they are not. The dissolved gass is, well dissolved, it's part of the liquid.
If it's in a bubble it's not dissolved in the liquid.
Get a glass of water. There is dissolved CO2 in it.
We make DI water for our wash machine. As it is made it has a PH of 7. I havn't checked but have been told that it quickly goes down minutely because it dissolves CO2 out of the air.
Get some cold water out of your tap. Put in ice cube trays. Put it in the freezer, you will see when it freezes that it is cloudy. This is air undisolveing as the water freezes. But you didn't see bubbles before you froze it did you?
And your number 2 doesn't make sense.
It doesn't matter where the bubbles are. They can be spread throughout the pop or at the top. And I don't believe the dissolved gas adds any pressure, it's only when it comes out of solution to form bubbles that it contributes to the pressure.
I want to make sure I understand you.
Are you thinking that the bubbles are the dissolved gas?
Because they are not. The dissolved gass is, well dissolved, it's part of the liquid.
If it's in a bubble it's not dissolved in the liquid.
Get a glass of water. There is dissolved CO2 in it.
We make DI water for our wash machine. As it is made it has a PH of 7. I havn't checked but have been told that it quickly goes down minutely because it dissolves CO2 out of the air.
Get some cold water out of your tap. Put in ice cube trays. Put it in the freezer, you will see when it freezes that it is cloudy. This is air undisolveing as the water freezes. But you didn't see bubbles before you froze it did you?
QUOTE (mr_homm+May 29 2008, 02:54 AM)
Of course, it may be true that for CANS, the permeability is so low that the gas does not diffuse out, so my explanation may only apply to plastic bottles.
--Stuart Anderson
Once I saw a can of pop slammed on a table instead of being shaken. The can then burst open. To me this would indicate that the pressure did indeed go up do to the mechanical shock.
another time I was driving with some cans in the back of the car. I went over a bump and heard a noise. then I noticed my car top was dripping. Later I found a can that had burst open. Now it may have been strictly because of the can getting warmer but I doubt it.
--Stuart Anderson
Once I saw a can of pop slammed on a table instead of being shaken. The can then burst open. To me this would indicate that the pressure did indeed go up do to the mechanical shock.
another time I was driving with some cans in the back of the car. I went over a bump and heard a noise. then I noticed my car top was dripping. Later I found a can that had burst open. Now it may have been strictly because of the can getting warmer but I doubt it.
QUOTE
And your number 2 doesn't make sense.
See this. This is called arguing for the sake of arguing. Not because of the info, but because of the person.
Take a new bottle of pop (soda). Look inside and you will see very few bubbles (if any). Crack open the bottle and you will see bubble appear withing the pop. Open it until there is no his and you will see bubbles form and rise to the surface. Close the bottle. Over time the bubbles that form and rise will build up a pressure and more bubbles will stop forming when an equilibrium is obtained.
QUOTE (->
| QUOTE |
| And your number 2 doesn't make sense. |
See this. This is called arguing for the sake of arguing. Not because of the info, but because of the person.
Take a new bottle of pop (soda). Look inside and you will see very few bubbles (if any). Crack open the bottle and you will see bubble appear withing the pop. Open it until there is no his and you will see bubbles form and rise to the surface. Close the bottle. Over time the bubbles that form and rise will build up a pressure and more bubbles will stop forming when an equilibrium is obtained.
So light needs to accelerate to get up to speed but gas dissolves instantly?
Where was the use of the word "instantly"? I believe I said "eventually" at one point which implies a passing of time.
QUOTE
Are you thinking that the bubbles are the dissolved gas?
The bubbles were once dissolved gas. That is what I meant. An increase in bubble results in a decrease in dissolved gas provided that the gas that comprises the bubble once was the dissolved gas.
Bad wording on my part. Sorry.
QUOTE (->
| QUOTE |
| Are you thinking that the bubbles are the dissolved gas? |
The bubbles were once dissolved gas. That is what I meant. An increase in bubble results in a decrease in dissolved gas provided that the gas that comprises the bubble once was the dissolved gas.
Bad wording on my part. Sorry.
Get a glass of water. There is dissolved CO2 in it.
There is also atmospheric pressure being applied onto it. We have a machine for testing the contamination of hydraulic oil taken from aircrafts. Before the machine can be used on the oil, the oil must first be put into a chamber where it undergoes a decrease in atmospheric pressure. This forces dissolved gas (that can interfere with the testing) to form bubbles and rise to the surface.
Wow! This topic seems to attract the imagination of many people. Thanks to all of you!
I too consider that the pressure in the bottle increases, and not just by a few millibars, because I too feel the brutal tension in the walls of a plastic bottle when the beverage has been shaken. As a comparison, the stiffening of the bottle by your lung's pressure, which is about a quarter atmosphere, is much weaker.
The dissolved CO2 is in equilibrium with the gaseous CO2 over the liquid, which is a bit over atmospheric pressure when the bottle is filled and stored. But why should the pressure increase when shaken? Neither the temperature nor the chemical composition is changed.
A long quiet storage doesn't increase the pressure neither, so I don't believe shaking simply accelerates some degassing.
I too consider that the pressure in the bottle increases, and not just by a few millibars, because I too feel the brutal tension in the walls of a plastic bottle when the beverage has been shaken. As a comparison, the stiffening of the bottle by your lung's pressure, which is about a quarter atmosphere, is much weaker.
The dissolved CO2 is in equilibrium with the gaseous CO2 over the liquid, which is a bit over atmospheric pressure when the bottle is filled and stored. But why should the pressure increase when shaken? Neither the temperature nor the chemical composition is changed.
A long quiet storage doesn't increase the pressure neither, so I don't believe shaking simply accelerates some degassing.
The C2 explanation is that shaking a fizzy drinl bottle produces very small bubbles with very high pressure due to surface tension .. the bubbles subsequently coalesce into larger bubbles .. the rest is hydraulics. A bottle containing just air and water does not contain enough excess gas to produce the effect .. the C2 effect predicts shaking will (slightly) reduce the internal pressure of a bottle containing just air and water in equilibrium.
Hi 5D,
Let's do this in easy steps..
If you look at the page here http://en.wikipedia.org/wiki/Interfacial_tension (click on the link) you'll see that inside a 1um bubble there is an excess pressure of 1.46 atmospheres. If we start with (say) 10cm^3 of air and shake it up in water so it all ends up in (say) 1um bubbles .. what volume will it occupy? Will it be MORE or LESS than 10cm^3 ?
-C2.
Let's do this in easy steps..
If you look at the page here http://en.wikipedia.org/wiki/Interfacial_tension (click on the link) you'll see that inside a 1um bubble there is an excess pressure of 1.46 atmospheres. If we start with (say) 10cm^3 of air and shake it up in water so it all ends up in (say) 1um bubbles .. what volume will it occupy? Will it be MORE or LESS than 10cm^3 ?
-C2.
Hi 5D,
Saturated solutions are an advanced topic which we won't attempt until we've established we know the relationship between pressure and volume .. (try to remember that this is physics for bozos .. we have to take small steps)
Just try the question again .. eventually you might see why I'm asking it.
-C2.
Saturated solutions are an advanced topic which we won't attempt until we've established we know the relationship between pressure and volume .. (try to remember that this is physics for bozos .. we have to take small steps)
Just try the question again .. eventually you might see why I'm asking it.
-C2.
QUOTE (5D+)
In addition, headspace pressure in typical Cola bottles is around twice atomospheric pressure. - see where I going with this ?
I think you are heading in the direction of being able to explain to the nurse why you are covered in a sticky brown liquid - whether or not she will believe you is another matter.
-C2.
I think you are heading in the direction of being able to explain to the nurse why you are covered in a sticky brown liquid - whether or not she will believe you is another matter.
-C2.
Out of respect for the decent folk posting on this thread/forum I have reported the last two posts and asked for them to be removed .. I hope others will do the same. Thank you. -C2.
Just curious of something said earlier. Does dissolved gas really not exert any pressure? That is given a bottle of pop, does the dissolved gas not contribute to the pressure found within the bottle?
The reason being because of the existence of TGP probes.
TGP = Total dissolved Gas Pressure.
The reason being because of the existence of TGP probes.
TGP = Total dissolved Gas Pressure.
May I remind that disregarding words are not considered as convincing arguments in a scientific discussion?
C2,
You´re feeding them again !! This could lead to an even faster rate of reproduction !!
all the best
E3
You´re feeding them again !! This could lead to an even faster rate of reproduction !!
all the best
E3
Tiny bubbles are an interesting direction.
I had read a long time ago, but have largely forgotten, that the gas <-> solution equilibrium is displaced when bubbles (or droplets) are small. Could it be a simple geometrical effect, because the strong curvature means that gas molecules located, say, one mean free path over the solution, are less abundant since the smaller sphere there has less area?
Then more CO2 would evaporate to a tiny bubble than it would at a flat surface.
But maybe my memory is simply too bad.
Oversaturated solution: no. As I already wrote, a long storage doesn't have this effect, even in a metal can upside down, which has visibly no leak.
Sugar: no. I saw the effect on Coca light, which contains none. It is, in fact, water with CO2 and very little more. Carbohydrates are under 1g per 100g liquid. All aromas, vegetal extracts, caramel colour that make the difference with tap water and industrial CO2 are together well under 1%.
Pressure from the dissolved gas: how to tell? As soon as the free gas in the bottle has a pressure, the liquid or solution transmits this pressure. It could be hydraulic oil or liquid Ga-In-Sn alloy (Galinstan), with no CO2 dissolved, and these liquids would transmit the free gas' pressure.
What is sure is that the pressure of the free gas increases (as much as the liquid's pressure) and for that, some gas must escape from the solution.
I had read a long time ago, but have largely forgotten, that the gas <-> solution equilibrium is displaced when bubbles (or droplets) are small. Could it be a simple geometrical effect, because the strong curvature means that gas molecules located, say, one mean free path over the solution, are less abundant since the smaller sphere there has less area?
Then more CO2 would evaporate to a tiny bubble than it would at a flat surface.
But maybe my memory is simply too bad.
Oversaturated solution: no. As I already wrote, a long storage doesn't have this effect, even in a metal can upside down, which has visibly no leak.
Sugar: no. I saw the effect on Coca light, which contains none. It is, in fact, water with CO2 and very little more. Carbohydrates are under 1g per 100g liquid. All aromas, vegetal extracts, caramel colour that make the difference with tap water and industrial CO2 are together well under 1%.
Pressure from the dissolved gas: how to tell? As soon as the free gas in the bottle has a pressure, the liquid or solution transmits this pressure. It could be hydraulic oil or liquid Ga-In-Sn alloy (Galinstan), with no CO2 dissolved, and these liquids would transmit the free gas' pressure.
What is sure is that the pressure of the free gas increases (as much as the liquid's pressure) and for that, some gas must escape from the solution.
And eventually I looked at the Wiki page linked by Confused2:
http://en.wikipedia.org/wiki/Interfacial_tension
which tells much useful information relevant to the discussion.
- Sugar has no effect on water's surface tension
- Vapour pressure of tiny droplets is bigger than for a flat surface (see just above the pictures gallery). Maybe the free gas pressure of a solution does the same.
http://en.wikipedia.org/wiki/Interfacial_tension
which tells much useful information relevant to the discussion.
- Sugar has no effect on water's surface tension
- Vapour pressure of tiny droplets is bigger than for a flat surface (see just above the pictures gallery). Maybe the free gas pressure of a solution does the same.
Sec, you should choose better data sources.
Handbook of Chemistry and Physics:
The surface tension of water changes only from 72 to 75.7 mN/m when increasing the diluted sucrose from 0% to 50% weight. In other words: no significant effect.
Confused2 has brought useful inputs in this discussion. You have only brought false data, false ideas and disregard.
You can't make science from data picked at answers.yahoo.
You can't make science from insults.
You can't make science at all.
Handbook of Chemistry and Physics:
The surface tension of water changes only from 72 to 75.7 mN/m when increasing the diluted sucrose from 0% to 50% weight. In other words: no significant effect.
Confused2 has brought useful inputs in this discussion. You have only brought false data, false ideas and disregard.
You can't make science from data picked at answers.yahoo.
You can't make science from insults.
You can't make science at all.
Thought I'd add my two cents. Shaking the cola adds mechanical energy to it, and since shaking is quite a turbulent process that mechanical energy quickly becomes heat. This heat will increase the temperature of the liquid and gas phases, decreasing the solubility of the CO2 and increasing the pressure of the gas. The pressure should increase even if there is no degassing of the liquid.
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