Closing off your airflow when refilling tanks. ???

[Cliffyboy1962]

I have been vaping for a year now and one of the first things I remember picking up on was

"You gotta close off your airflow when refilling your top fill tanks"

When I first heard this I thought "Huh ?, what could that possibly do ?"

Well to cut a long story short, I sat and thought about this many times and kept coming up blank. Some people said "when you top fill your tank, the vacuum in the top of the tank that is helping stop your juice from moving through the juice holes, into the airflow section, is lost and closing off the airflow will somehow help this"

I thought "OK but that doesn't make any sense because the air pressure on the airflow side will not change regardless of airflow shut or open because the whole section is open to atmosphere, at the top (chimney end)"

Then I thought "maybe if juice leaks through into the airflow section, closing the airflow holes/slots will stop it coming out of the tank" yeah but only until you open them again, then it would just pour out anyway.

So please put an end to my misery and pain, explain to me why this is recommended and what it achieves because it is lost on me.

 

[nwhornet]

It's to stop the tank dumping it's contents when you open the top fill, change in pressure/vacuum. I found out from bitter experience. Didn't learn 'cause still occasionally forget to shut of juice & air flow . Some tanks are more susceptible than others.

 

[jsixtysix]

Got to use the plug before turning on the taps if you ever want to fill the bath

 

[speedfreek67]

I think of it like this:

As you vape and the level of juice goes down, in the air-space at the top of the tank the pressure in that space is slightly less than 1 atmosphere - so there is negative pressure above the juice.

As you vape and the juice level goes down, the air pressure inside tries to equalise with the pressure outside - hence the bubbles that come out of the wicking holes and travel up through the juice into the space above.

If you close the bottom air flow, the pressure cannot equalise. There is more pressure in the space below, between the airflow holes and the coil, than there is above, between the juice and the top of the tank.

If you open the top of the tank, you now have 1 atmosphere of pressure pushing down on the juice from above. Also, the juice will want to run down through the tank, due to the weight of the juice!

If the bottom airflow is open when you open the top of the tank, the juice will start to sink through the coil and out of the bottom, because there is no difference in the air pressure below the juice to the pressure above.

But... if the bottom airflow is closed, there is a constant air pressure below the juice. The weight of the juice pushing downwards will *increase* that pressure slightly, to slightly above 1 atmosphere.

Imagine a drinking straw - if you suck a little juice up a straw and then put your thumb over the bottom, the small amount of juice stays up the straw with air between it and your thumb below. Remove your thumb and it runs out...

{/end stupidly longwinded train of thought}

 

[mick brown]

It's not necessary on all tanks.
I don't on my cleito or my isub G ( this might be because the isub is bottom fill ) but on my rta's I have to. The only rta's that I don't are the Merlin and Kayfun v5 but you have to close the juice flow control before taking the top off.

 

[vandykevapes]

i have to on my limitless xl otherwise i end up with a puddle ! other then that amazing tank

 

[Arctic_Wolf]

I only do it with the Griffins.

Anything else, I don't bother .

 

[Screwball]

Never have on my tfv4 and never had a problem

 

[Richy]

Never have with my cleito's

 

[Cliffyboy1962]

Thank you for going to the trouble of attempting an explanation for this dilemma.

I think of it like this:

As you vape and the level of juice goes down, in the air-space at the top of the tank the pressure in that space is slightly less than 1 atmosphere - so there is negative pressure above the juice.

I am OK with this bit. This is the first part of the straw analogy.

As you vape and the juice level goes down, the air pressure inside tries to equalise with the pressure outside - hence the bubbles that come out of the wicking holes and travel up through the juice into the space above.

Firstly would you agree that air can travel freely through the airholes at the bottom, up through the coil and out of the chimney to the drip tip and out to your mouth ? After all, this is how it works.

If you close the bottom air flow, the pressure cannot equalise.

OK Now why can the pressure not equalise ?

There is still a direct connection betwen this chamber and atmosphere, through the coil and up to the chimney.

There is more pressure in the space below, between the airflow holes and the coil, than there is above, between the juice and the top of the tank.

Unlikely seeing as equalisation has been occuring all the time up to point of refill.

If you open the top of the tank, you now have 1 atmosphere of pressure pushing down on the juice from above. Also, the juice will want to run down through the tank, due to the weight of the juice!

Agreed.

If the bottom airflow is open when you open the top of the tank, the juice will start to sink through the coil and out of the bottom, because there is no difference in the air pressure below the juice to the pressure above.

Agreed, unless the coil has been designed to prevent this.

But... if the bottom airflow is closed, there is a constant air pressure below the juice. The weight of the juice pushing downwards will *increase* that pressure slightly, to slightly above 1 atmosphere.

Can't see how ?, as surely any increase in pressure here will vent to atmosphere up the chimney.

Imagine a drinking straw - if you suck a little juice up a straw and then put your thumb over the bottom, the small amount of juice stays up the straw with air between it and your thumb below. Remove your thumb and it runs out...

{/end stupidly longwinded train of thought}

The one thing I can think of that might affect this reasoning is the main variable here. The coil bore dimensions (much thinner on earlier coils and tending to get larger more recently) and coil design. But, no matter how small the hole trough the coil up to the chimney, there has to be an air gap, or the thing wouldn't work.

Still don't get what closing the airflow holes actually does. Is it voodoo ?