What causes cigarette lighter gas to flow from the refill into the 
lighter? Is it gravity or pressure?

Just because, Andrew is AWOL

-- 

Regards
     Stephen

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On 16-11-2014 12:17, Stephen wrote:
> What causes cigarette lighter gas to flow from the refill into the
> lighter? Is it gravity or pressure?
>
> Just because, Andrew is AWOL
>

Pressure, My guess.

Thomas

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On 16/11/2014 12:54, Thomas de Groot wrote:
> On 16-11-2014 12:17, Stephen wrote:
>> What causes cigarette lighter gas to flow from the refill into the
>> lighter? Is it gravity or pressure?
>>
>> Just because, Andrew is AWOL
>>
> 
> Pressure, My guess.
> 
> Thomas
> 
It's a liquid... pushed by its own vaporized gas on the free surface
(inside the refiller can).

To refill (quite an old practice, nowadays with no-refill lighters), the
difference of pressure (from empty lighter with nearly no more gas vs
the refill at whole pressure due to the big amount of liquid providing
enough gas on the free part) found on its way the liquid and push it to
the weakest part (the empty lighter)

That is for the butane lighters.

Now, if you are using an old Zippo, the refill is with nafta and there
is no pressure, just gravity, like when you pour a drink.

-- 
IQ of crossposters with FU: 100 / (number of groups)
IQ of crossposters without FU: 100 / (1 + number of groups)
IQ of multiposters: 100 / ( (number of groups) * (number of groups))

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On 16/11/2014 12:22, Le_Forgeron wrote:
> On 16/11/2014 12:54, Thomas de Groot wrote:
>> On 16-11-2014 12:17, Stephen wrote:
>>> What causes cigarette lighter gas to flow from the refill into the
>>> lighter? Is it gravity or pressure?
>>>
>>> Just because, Andrew is AWOL
>>>
>>
>> Pressure, My guess.
>>
>> Thomas
>>
> It's a liquid... pushed by its own vaporized gas on the free surface
> (inside the refiller can).
>
> To refill (quite an old practice, nowadays with no-refill lighters), the
> difference of pressure (from empty lighter with nearly no more gas vs
> the refill at whole pressure due to the big amount of liquid providing
> enough gas on the free part) found on its way the liquid and push it to
> the weakest part (the empty lighter)
>
> That is for the butane lighters.
>
> Now, if you are using an old Zippo, the refill is with nafta and there
> is no pressure, just gravity, like when you pour a drink.
>
You are both saying pressure and yes I am talking about butane lighters.
Consider this, the pressure differential between the gas cylinder and 
the lighter is equalised within a fraction of a second. Yet still the 
liquid flows after that.


-- 

Regards
     Stephen

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On 16/11/2014 13:48, Stephen wrote:

> You are both saying pressure and yes I am talking about butane lighters.
> Consider this, the pressure differential between the gas cylinder and
> the lighter is equalised within a fraction of a second.

How ? the lighter has a depleted pressure chamber, and only liquid is
flowing from the refiller.

Yes, adding liquid to the lighter gives back a bit of pressure for the
lighter's side, but not enough. The fresh liquid could vaporize to
provide more gas but that transformation requires a lot of heat which is
not available at the refill time.

> Yet still the
> liquid flows after that.
> 
> 


-- 
IQ of crossposters with FU: 100 / (number of groups)
IQ of crossposters without FU: 100 / (1 + number of groups)
IQ of multiposters: 100 / ( (number of groups) * (number of groups))

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On 16/11/2014 12:56, Le_Forgeron wrote:
> On 16/11/2014 13:48, Stephen wrote:
>
>> You are both saying pressure and yes I am talking about butane lighters.
>> Consider this, the pressure differential between the gas cylinder and
>> the lighter is equalised within a fraction of a second.
>
> How ? the lighter has a depleted pressure chamber, and only liquid is
> flowing from the refiller.
>

But it is only liquid because it is under pressure. As soon as some 
liquid is in the lighter it vaporises to fill the chamber and if the 
resultant pressure is less than the pressure in the gas cylinder more 
liquid will go into the lighter until the system will reach stability.

> Yes, adding liquid to the lighter gives back a bit of pressure for the
> lighter's side, but not enough. The fresh liquid could vaporize to
> provide more gas but that transformation requires a lot of heat which is
> not available at the refill time.
>
The heat is taken from the air and the hand that is holding it. You can 
feel the lighter getting cold and you can hear the butane rushing into 
the lighter. The sound will stop when the pressure has equalised and the 
lighter will continue to fill up.

>> Yet still the
>> liquid flows after that.
>>
>>
>
>


-- 

Regards
     Stephen

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On 16-11-2014 15:13, Stephen wrote:
> The heat is taken from the air and the hand that is holding it. You can
> feel the lighter getting cold and you can hear the butane rushing into
> the lighter. The sound will stop when the pressure has equalised and the
> lighter will continue to fill up.
>

Such a long time since I stopped smoking that I only dimly remember 
these things. The cold comes from the gas expanding, right? Same way as 
a fridge. Your last sentence seems contradictory to me. With equal 
pressure no further fill up, or am I wrong (probability: 98%)?

Thomas

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On 16/11/2014 15:48, Thomas de Groot wrote:
> On 16-11-2014 15:13, Stephen wrote:
>> The heat is taken from the air and the hand that is holding it. You can
>> feel the lighter getting cold and you can hear the butane rushing into
>> the lighter. The sound will stop when the pressure has equalised and the
>> lighter will continue to fill up.
>>
>
> Such a long time since I stopped smoking that I only dimly remember
> these things. The cold comes from the gas expanding, right? Same way as
> a fridge.

Correct.

> Your last sentence seems contradictory to me. With equal
> pressure no further fill up, or am I wrong (probability: 98%)?
>

And the argument is: If it is not a difference in pressure then it must 
be gravity that is making the liquid flow.
And because you do not have the opportunity to do the experiment 
yourself. If when you are filling a lighter and you turn the system 
upside down so that the lighter is above the gas cylinder. A lot of the 
liquid drains into the gas cylinder. Gravity?
Some cigarette lighters have the chamber split into two by a dividing 
weir. If you keep the liquid in the chamber underneath the valve. The 
liquid will rise to the top of the weir and stop rising. No more gas 
will go in. Then if you tip the lighter so that the liquid spills into 
other chamber. The empty part (under the valve) can then be filled.

I first had this discussion 25 years ago and would quite like to know 
the answer.


-- 

Regards
     Stephen

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> And the argument is: If it is not a difference in pressure then it must
> be gravity that is making the liquid flow.

It's sort of both.
Picture instead the ordinary case of filling a vessel with liquid at atmospheric
pressure through a narrow orifice.
At first there may be a rapid flow of liquid until the headspace gets compressed
and builds up pressure.
THEN there needs to be a chance for the gaseous headspace to bubble up and trade
volume with the liquid for there to be a mass transfer.
The problem lies in only one very narrow tube for bidirectional flow.

If there were a two-way filling mechanism, or a way to vent the gaseous
headspace, then you'd get rapid filling.

Another alternative might be to iteratively overfill with liquid by an increase
in pressure, or by chilling and contracting the headspace, and then letting the
back-pressure bubble up back into the fill vessel.

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On 16-11-2014 22:59, Bald Eagle wrote:
>
>> And the argument is: If it is not a difference in pressure then it must
>> be gravity that is making the liquid flow.
>
> It's sort of both.
> Picture instead the ordinary case of filling a vessel with liquid at atmospheric
> pressure through a narrow orifice.
> At first there may be a rapid flow of liquid until the headspace gets compressed
> and builds up pressure.
> THEN there needs to be a chance for the gaseous headspace to bubble up and trade
> volume with the liquid for there to be a mass transfer.
> The problem lies in only one very narrow tube for bidirectional flow.
>
> If there were a two-way filling mechanism, or a way to vent the gaseous
> headspace, then you'd get rapid filling.
>
> Another alternative might be to iteratively overfill with liquid by an increase
> in pressure, or by chilling and contracting the headspace, and then letting the
> back-pressure bubble up back into the fill vessel.
>

I find this explanation neat, although I am not entirely satisfied 
somehow. Imho the problem resides in the fact that the liquid is a 
compressed gas which will want to expand as soon as there is a 
possibility for it. I dimly remember that refilling a lighter often gave 
frustrating results as it was impossible to refill up to the initial 
level... with the exception of the use of a /pressurised/ filling mechanism.

Thomas

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> But it is only liquid because it is under pressure. As soon as some
> liquid is in the lighter it vaporises to fill the chamber and if the
> resultant pressure is less than the pressure in the gas cylinder more
> liquid will go into the lighter until the system will reach stability.
>
>> Yes, adding liquid to the lighter gives back a bit of pressure for the
>> lighter's side, but not enough. The fresh liquid could vaporize to
>> provide more gas but that transformation requires a lot of heat which is
>> not available at the refill time.
>>
> The heat is taken from the air and the hand that is holding it. You can
> feel the lighter getting cold and you can hear the butane rushing into
> the lighter. The sound will stop when the pressure has equalised and the
> lighter will continue to fill up.

I haven't had chance to think in detail what is happening (nor do I have 
much experience with refilling lighters), but I suspect a good 
understanding of vapour pressure and how it changes with temperature is 
required:

http://en.wikipedia.org/wiki/Vapor_pressure
http://en.wikipedia.org/wiki/Butane_(data_page)#Vapor_pressure_of_liquid

Also bear in mind that it might not be 100% pure butane in the refill 
(or there might be some air in the lighter), so you better also know 
about partial pressure :-)

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

It sounds to me from what you describe that it's got something to do 
with things heating up or cooling down, causing the vapour pressure to 
change. An interesting experiment would be to prepare the lighter to be 
cooler or warmer than the refill canister and note any difference in 
behaviour when it is refilled.

Post a reply to this message

> The heat is taken from the air and the hand that is holding it. You can
> feel the lighter getting cold and you can hear the butane rushing into
> the lighter. The sound will stop when the pressure has equalised and the
> lighter will continue to fill up.

One possibility is that the sound you hear is actually a small amount of 
gas flowing rapidly into the lighter (or liquid that instantly 
evaporates as it hits the low pressure in the empty lighter) before the 
liquid starts to flow through the opening. When the sound stops that 
isn't because the pressure has equalised, just that it is liquid flowing 
much slower then rather than gas flowing quickly.

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On 11/16/2014 10:42 AM, Stephen wrote:
> On 16/11/2014 15:48, Thomas de Groot wrote:
>> On 16-11-2014 15:13, Stephen wrote:
>>> The heat is taken from the air and the hand that is holding it. You can
>>> feel the lighter getting cold and you can hear the butane rushing into
>>> the lighter. The sound will stop when the pressure has equalised and the
>>> lighter will continue to fill up.
>>>
>>
>> Such a long time since I stopped smoking that I only dimly remember
>> these things. The cold comes from the gas expanding, right? Same way as
>> a fridge.
>
> Correct.
>


Almost, but not fully.

The cold comes from the phase change from liquid to gas (It takes energy 
to evaporate the liquid, and the liquid will happily do so, because the 
equilibrium favors the gas phase (lower pressure on the cold side) If 
there is not enough pressure on the hot side (i.e. not enough coolant) 
to condense the gas to a liquid, the refrigeration is minimal to 
nonexistent.


... As for the rest of the conversation, it's fascinating; I think it's 
pressure difference that fills the lighter.

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On 17-11-2014 15:09, Raiford, Michael wrote:
> On 11/16/2014 10:42 AM, Stephen wrote:
>> On 16/11/2014 15:48, Thomas de Groot wrote:
>>> On 16-11-2014 15:13, Stephen wrote:
>>>> The heat is taken from the air and the hand that is holding it. You can
>>>> feel the lighter getting cold and you can hear the butane rushing into
>>>> the lighter. The sound will stop when the pressure has equalised and
>>>> the
>>>> lighter will continue to fill up.
>>>>
>>>
>>> Such a long time since I stopped smoking that I only dimly remember
>>> these things. The cold comes from the gas expanding, right? Same way as
>>> a fridge.
>>
>> Correct.
>>
>
>
> Almost, but not fully.
>
> The cold comes from the phase change from liquid to gas (It takes energy
> to evaporate the liquid, and the liquid will happily do so, because the
> equilibrium favors the gas phase (lower pressure on the cold side) If
> there is not enough pressure on the hot side (i.e. not enough coolant)
> to condense the gas to a liquid, the refrigeration is minimal to
> nonexistent.

Ah! Thank you for that correction. Phase change indeed.

>
>
> ... As for the rest of the conversation, it's fascinating; I think it's
> pressure difference that fills the lighter.
>

That's my best guess too.

Thomas

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Cooling in refrigeration is accomplished by adiabatic expansion of the
refrigerant gas - a rapid increase in the entropy due to the phase change from
liquid to gas.  From the ideal gas laws, P1V1/T1 = P2V2/T2   Change the pressure
and volume, and the temperature changes as a consequence.  See "Carnot cycle".

> I find this explanation neat, although I am not entirely satisfied
> somehow. Imho the problem resides in the fact that the liquid is a
> compressed gas which will want to expand as soon as there is a
> possibility for it.

That's irrelevant once the pressure differential between the two containers is
equilibrated.  What evaporated into gas can be recompressed back into liquid.

> I dimly remember that refilling a lighter often gave
> frustrating results as it was impossible to refill up to the initial
> level... with the exception of the use of a /pressurised/ filling mechanism.
>
> Thomas

Yes, when refilling with butane the filling container is obviously pressurized.

I believe that there are several interrelated issues here.

First, most people hold the butane refiller to the refilling valve, depress, and
then it's over and done with.  The system has not been given a chance to attain
equilibrium.

Second, there is likely to be a mixture of gases at play -

From http://lighterreviews.com/butane/  :

"Butane, is either of two isomeric flammable gaseous alkanes C4H10 usually
obtained from petroleum or natural gas and used as a fuel. Most butane for cigar
lighters is a mixture of of butane as noted above, isobutene , propane and a
small amount of air (yup the stuff we breath everyday). "

When you use the lighter, the butane flows from the bottom, through a "dip
tube".
http://www.inpharmix.com/jps/_images/exploded%20lighter%20labeled.jpg

Which means that the less volatile components, the ones that tend to remain
liquid as the lighter gets used, are pushed out by the headspace gas - composed
of the comparatively less liquifiable components.  After several
discharge/refill cycles, the lighter becomes filled with a higher proportion of
less liquifiable compounds, and so requires either more pressure to complete the
same fuel transfer, or venting of the more volatile components.

You could hold down the fuel lever to vent these gases before refilling, or more
effectively, hold the partially full lighter upside down while doing so -
causing the expansion of the less volatile components to push the more volatile
ones out the dip tube (which is now at the top).
You could then refill the lighter which has been depleted of those other
components.

To enhance filling, you could heat the butane refiller while filling with warm
water or a towel soaked in hot water.  Alternatively, you could chill the
lighter in the freezer before filling.

And, you could just wait and keep the filler depressed against the lighter for
far longer than most people do so that equilibrium can be more closely achieved.

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On 17/11/2014 17:04, Bald Eagle wrote:
> That's irrelevant once the pressure differential between the two containers is
> equilibrated.  What evaporated into gas can be recompressed back into liquid.
>

Yes, if we ignore heat transfer from the outside it is a closed system.

>> >I dimly remember that refilling a lighter often gave
>> >frustrating results as it was impossible to refill up to the initial
>> >level... with the exception of the use of a/pressurised/  filling mechanism.
>> >
>> >Thomas
> Yes, when refilling with butane the filling container is obviously pressurized.
>
> I believe that there are several interrelated issues here.
>

Nicely observed and the image is handy too.

 > http://www.inpharmix.com/jps/_images/exploded%20lighter%20labeled.jpg

I think that there is an additional factor. As Scott pointed out vapour 
pressure might have something to do with it as well. I did mention but 
it was probably overlooked.
When you fill the lighter the liquid fills the part of the chamber below 
the valve then stops. (Using the image you posted. The central divider 
in the lighter body, is the other way around and the gap is at the valve 
end.) At this point the system is in equilibrium. If you then pour some 
of the liquid into the empty part. You can fill the lighter to a similar 
level in the first chamber.
So I am guessing that it has to do with a function of vapour pressure 
and the distance from the top of the liquid to the inlet valve.


-- 

Regards
     Stephen

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On 17/11/2014 12:25, scott wrote:
>> The heat is taken from the air and the hand that is holding it. You can
>> feel the lighter getting cold and you can hear the butane rushing into
>> the lighter. The sound will stop when the pressure has equalised and the
>> lighter will continue to fill up.
>
> One possibility is that the sound you hear is actually a small amount of
> gas flowing rapidly into the lighter (or liquid that instantly
> evaporates as it hits the low pressure in the empty lighter) before the
> liquid starts to flow through the opening. When the sound stops that
> isn't because the pressure has equalised, just that it is liquid flowing
> much slower then rather than gas flowing quickly.
>

You could very well be right. I did not think of that.
Someone needs to do a doctoral theses on the subject. :-)

-- 

Regards
     Stephen

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Stephen <mca### [at] aolcom> wrote:

> When you fill the lighter the liquid fills the part of the chamber below
> the valve then stops. (Using the image you posted. The central divider
> in the lighter body, is the other way around and the gap is at the valve
> end.) At this point the system is in equilibrium. If you then pour some
> of the liquid into the empty part. You can fill the lighter to a similar
> level in the first chamber.

So....  what stops the gas from flowing over the top of the divider and
condensing into a liquid, yet at the same time allows the liquid butane to be
poured freely across the top?

When you use the lighter, do you empty one side, and then have to "refill" the
other side by pouring over from the other side?

Post a reply to this message

On 18/11/2014 15:53, Bald Eagle wrote:
> Stephen <mca### [at] aolcom> wrote:
>
>> When you fill the lighter the liquid fills the part of the chamber below
>> the valve then stops. (Using the image you posted. The central divider
>> in the lighter body, is the other way around and the gap is at the valve
>> end.) At this point the system is in equilibrium. If you then pour some
>> of the liquid into the empty part. You can fill the lighter to a similar
>> level in the first chamber.
>
> So....  what stops the gas from flowing over the top of the divider and
> condensing into a liquid, yet at the same time allows the liquid butane to be
> poured freely across the top?
>

Sorry, the lighter is disconnected from the refill at that point. Then 
reconnected to keep filling it. I've not tried to...

[Sounds of footsteps fading into the distance and returning]

Nothing, just tried it.
If my theory that brontosauruses are big and pointed at both ends, is 
right. Then the increase in pressure at the valve, as the liquid reaches 
it. Only, backs up the liquid from the butane cylinder, more. As I 
righted them, liquid started to flow into the empty part of the lighter.

> When you use the lighter, do you empty one side, and then have to "refill" the
> other side by pouring over from the other side?
>
>
>
Oo! Nice one! :-)
You almost got me with that. ;-)

-- 

Regards
     Stephen

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On 18-11-2014 17:44, Stephen wrote:
> On 18/11/2014 15:53, Bald Eagle wrote:
>> When you use the lighter, do you empty one side, and then have to
>> "refill" the
>> other side by pouring over from the other side?
>>

That happens automatically as a lighter is never constantly standing up 
right but is laying around, carried in pockets, shaken up, iow, 
mishandled ;-)

Thomas

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> As Scott pointed out vapour
> pressure might have something to do with it as well.

The vapour pressure of butane will determine the pressure of the refill 
can. When you fill a totally empty can with butane the pressure will 
build until it reaches the vapour pressure (about 2 bar absolute 
pressure at room temperature for butane), at this point any more butane 
you push in will condense out as liquid and the pressure will not 
increase any further.

The reverse happens if you were to slowly release the butane gas, this 
causes the pressure to momentarily drop in the can which allows some of 
the liquid to evaporate to restore the vapour pressure.

What you are doing in the refill situation though is to use the pressure 
in the can to force the liquid up into an "empty" lighter (due to the 
dip tube inside the refill can).

When you connect the lighter and refill can together the pressure in the 
can will force the liquid up the dip tube and into the lighter. 
Initially the pressure in the lighter is below the vapour pressure so 
the liquid will evaporate rapidly as it enters the lighter (the same as 
if you just sprayed it into the atmosphere). This will continue until 
the pressure is equalised and both the lighter and the refill can are at 
the vapour pressure of butane.

Based on that simple explanation there should never be any liquid 
flowing into the lighter. If the pressure in the lighter is below the 
vapour pressure then any liquid coming in will evaporate, and once it's 
at the vapour pressure then no more liquid will flow in due to the 
pressures being equal. But what I think happens is that when the first 
bit of liquid evaporates inside the lighter it reduces the temperature 
(eg it drops to 1.5 bar after a 10 degress C drop in temperature). What 
this means is that once the pressure in the lighter has reached 1.5 bar, 
the liquid entering it will no longer evaporate and will remain liquid. 
At this point liquid will continue to flow until the pressures (and 
temperatures?) have equalised.

Post a reply to this message

On 19/11/2014 09:01, scott wrote:
>> As Scott pointed out vapour
>> pressure might have something to do with it as well.
>
> The vapour pressure of butane will determine the pressure of the refill
> can. When you fill a totally empty can with butane the pressure will
> build until it reaches the vapour pressure (about 2 bar absolute
> pressure at room temperature for butane), at this point any more butane
> you push in will condense out as liquid and the pressure will not
> increase any further.
>
> The reverse happens if you were to slowly release the butane gas, this
> causes the pressure to momentarily drop in the can which allows some of
> the liquid to evaporate to restore the vapour pressure.
>

So far so good.

> What you are doing in the refill situation though is to use the pressure
> in the can to force the liquid up into an "empty" lighter (due to the
> dip tube inside the refill can).
>
> When you connect the lighter and refill can together the pressure in the
> can will force the liquid up the dip tube and into the lighter.

Oops! Are you using the photograph that Bald Eagle posted to work this 
out? That is a disposable non-refillable lighter. Refillable lighters 
have a different construction. The refill valve is on the bottom of the 
lighter in the section opposite to the dip tube and the internal wall is 
the other way round. So that the gap is at the bottom near the inlet valve.

> Initially the pressure in the lighter is below the vapour pressure so
> the liquid will evaporate rapidly as it enters the lighter (the same as
> if you just sprayed it into the atmosphere). This will continue until
> the pressure is equalised and both the lighter and the refill can are at
> the vapour pressure of butane.
>
> Based on that simple explanation there should never be any liquid
> flowing into the lighter. If the pressure in the lighter is below the
> vapour pressure then any liquid coming in will evaporate, and once it's
> at the vapour pressure then no more liquid will flow in due to the
> pressures being equal. But what I think happens is that when the first
> bit of liquid evaporates inside the lighter it reduces the temperature
> (eg it drops to 1.5 bar after a 10 degress C drop in temperature). What
> this means is that once the pressure in the lighter has reached 1.5 bar,
> the liquid entering it will no longer evaporate and will remain liquid.
> At this point liquid will continue to flow until the pressures (and
> temperatures?) have equalised.

I am not sure that I follow your logic. Are you saying that initially 
only gas flows then liquid?

-- 

Regards
     Stephen

Post a reply to this message

Le 19/11/2014 11:33, Stephen a écrit :
> On 19/11/2014 09:01, scott wrote:
>>> As Scott pointed out vapour
>>> pressure might have something to do with it as well.
>>
>> The vapour pressure of butane will determine the pressure of the refill
>> can. When you fill a totally empty can with butane the pressure will
>> build until it reaches the vapour pressure (about 2 bar absolute
>> pressure at room temperature for butane), at this point any more butane
>> you push in will condense out as liquid and the pressure will not
>> increase any further.
>>
>> The reverse happens if you were to slowly release the butane gas, this
>> causes the pressure to momentarily drop in the can which allows some of
>> the liquid to evaporate to restore the vapour pressure.
>>
> 
> So far so good.
> 
>> What you are doing in the refill situation though is to use the pressure
>> in the can to force the liquid up into an "empty" lighter (due to the
>> dip tube inside the refill can).
>>
>> When you connect the lighter and refill can together the pressure in the
>> can will force the liquid up the dip tube and into the lighter.
> 
> Oops! Are you using the photograph that Bald Eagle posted to work this
> out? That is a disposable non-refillable lighter. Refillable lighters
> have a different construction. The refill valve is on the bottom of the
> lighter in the section opposite to the dip tube and the internal wall is
> the other way round. So that the gap is at the bottom near the inlet valve.
> 
>> Initially the pressure in the lighter is below the vapour pressure so
>> the liquid will evaporate rapidly as it enters the lighter (the same as
>> if you just sprayed it into the atmosphere). This will continue until
>> the pressure is equalised and both the lighter and the refill can are at
>> the vapour pressure of butane.
>>
>> Based on that simple explanation there should never be any liquid
>> flowing into the lighter. If the pressure in the lighter is below the
>> vapour pressure then any liquid coming in will evaporate, and once it's
>> at the vapour pressure then no more liquid will flow in due to the
>> pressures being equal. But what I think happens is that when the first
>> bit of liquid evaporates inside the lighter it reduces the temperature
>> (eg it drops to 1.5 bar after a 10 degress C drop in temperature). What
>> this means is that once the pressure in the lighter has reached 1.5 bar,
>> the liquid entering it will no longer evaporate and will remain liquid.
>> At this point liquid will continue to flow until the pressures (and
>> temperatures?) have equalised.
> 
> I am not sure that I follow your logic. Are you saying that initially
> only gas flows then liquid?
> 

So far so good... but we can add a bit of complexity:

The pressure to liquify the butane is the partial pressure, not the
global pressure, whereas the flow to equilibrate pressure is about
global pressure.

In the empty lighter, global pressure is 1.0 bar (btw, it's now illegal,
should be in Pascal), and no partial pressure of butane.

In a filled lighter, all the pressure is from the butane, 2 bar when
unused. (but lower when lighted, as butane is going out)

In a refilling lighter, if any pressure is not from butane it is cooled
by the expensing butane and that system is not equilibrated, so it is a
bit difficult to know the global pressure, but it should be less than
1+butane.

In the refilling can, we have butane in liquid form pushed through a
pipe by: saturated butane gas and we can add some compressed nitrogen as
initial filling, for a global pressure that will be greater than the one
in the refilling lighter.

-- 
Just because nobody complains does not mean all parachutes are perfect.

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>>> When you connect the lighter and refill can together the pressure in the
>>> can will force the liquid up the dip tube and into the lighter.
>>
>> Oops! Are you using the photograph that Bald Eagle posted to work this
>> out? That is a disposable non-refillable lighter. Refillable lighters
>> have a different construction. The refill valve is on the bottom of the
>> lighter in the section opposite to the dip tube and the internal wall is
>> the other way round. So that the gap is at the bottom near the inlet valve.

I meant the dip tube inside the refill can, not the lighter.

>> I am not sure that I follow your logic. Are you saying that initially
>> only gas flows then liquid?

I am saying that initially the liquid butane evaporates as it enters the 
empty lighter, only after a certain pressure has built up in the lighter 
will the liquid from the refill can remain a liquid as it enters the 
lighter.

> The pressure to liquify the butane is the partial pressure, not the
> global pressure, whereas the flow to equilibrate pressure is about
> global pressure.

Correct, I had assumed only butane in the system in my working...

> In the empty lighter, global pressure is 1.0 bar (btw, it's now illegal,
> should be in Pascal), and no partial pressure of butane.

...wouldn't an "empty" lighter actually be full of butane gas at very 
slightly above 1 bar (often you can hear the gas escaping but it's not 
enough to make a flame)? Or should we assume some amount of air in there?

BTW I call it "total pressure" not "global pressure", so still legal 
here :-)

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On 19/11/2014 13:49, scott wrote:
> BTW I call it "total pressure" not "global pressure", so still legal
> here :-)

While I model it.
I prefer my pressure in "psi gauge".

As in 3-15 PSI ~ zero to full scale.

-- 

Regards
     Stephen

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I'm sorry, but Mr Stacey doesn't know the current location of Brains.

Are you SURE this is a job for International Rescue?

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On 20/11/2014 11:44, Orchid Win7 v1 wrote:
> I'm sorry, but Mr Stacey doesn't know the current location of Brains.
>

LOL
I said Big Brains not Wee Brains. ;-)

> Are you SURE this is a job for International Rescue?

Maybe not now you mention it. It is a job without any strings. :-)

-- 

Regards
     Stephen

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