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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