Tank type atomizers... For new vapists - how they work
"Tank" type atomizers... For new vapists - how they work, and why it's a good idea to know this.
Thought I'd throw something up to help relatively new (and some not so new) vapists understand how "tank" type, or RTA atomizers work.
Bear in mind, in this instance, the word tank can be used to describe most any clearo, glasso or carto tank... as well as RTAs.
The common denominator is that all of the above tank devices are functionally dependent on what's called, a "pressure differential". A techno term meaning that both high, or positive (in this context, atmospheric) and low or negative (vacuum or, in this context, less than atmospheric) air pressure are in play.
There is high pressure in the air tube (or "chimney") that rises to the drip tip and down to the coil... and out the bottom to the 510/eGo connection, or adjustable air control orifice. In the tank with the juice - under normal operating conditions... we find low pressure, or vacuum.
Still with me? Good.
I can't go further without talking briefly about wicks. Wicks have a few jobs - one of course, to wick juice to the coil so it can be vaporized, and two, the lesser known... is to function as a pressure seal. Not a perfect seal mind you... but one with a slow leak, that works both ways.
Not all PD atomizers use a wick in the latter description, but instead may use a series of orifices, where the dimension controls the transfer of both pressure, and with that, juice. The Kayfun design is the best example of this design.
More with wicks in a bit... promise.
So, how does negative pressure get in the tank when all around us is atmospheric or negative pressure? Well, that would be dependent on you... drawing on the drip tip. The temporary vacuum you create pulls juice, and that positive pressure you started with in the tank, into the coil head area... and a modest vacuum in the tank is produced.
Draw again... vacuum is enforced and perhaps even enhanced. Not a tremendous amount of vacuum... because most of our "lung generated vacuum" is directed out the venting system - and remember, our wick/pressure seal - still has that slow leak.
All else being equal, as our fluid column lowers, the negative pressure you've established above that fluid level will continue to be enforced and enhanced as well.
If we close (or even restrict) the atmospheric venting system and take a draw, what happens? That's right... most to ALL our vacuum is directed to the liquid tank... and depending on our seal (or control orifice) design, we may end up drawing juice right past that and into our coil/atomizing chamber.
This may be advantageous... in that with some atomizers, increasing the vacuum - immediately after filling or refilling and closing the system up - is key to both preventing leakage and to a lesser degree, priming the wick.
Does the vacuum last forever? With a wick seal - unlikely. If you walk away from a wick seal type atty that you were using... the vacuum may be slowly supplanted by positive pressure. How much or how long is a variable of the atty and the wick/seal.
This may be why your atty can be a bit gurgly (or you may find the 510/eGo positive "well" a bit wet) when you pick it up again... until you reestablish a vacuum with a few draws.
Once again - The pressure differential, in concert with wick seals and/or control orifices is why tanks don't leak like sieves - and why, when you refill a tank and introduce positive pressure back into it, they may gurgle a bit until a vacuum is reestablished.
And now... more on that all important wick/seal. If you're using a clearo/glasso of the Kanger BCC variety, it's (very) common to play with wicks. Removing flavor wicks, changing wick thickness and materials - and generally tweaking the pressure differential "seal"... without much thought to the fact that it functions as a seal .
Take out too much and the atty gurgles and even leaks. Add too much, or to "tight" a compression - and you get dry hits - and if a cotton wick, burnt gym sock flavored hits.
When you start to fine tune wick systems, with ball cotton perhaps being the most currently popular DIY wick material... take a moment to consider - "Is this (dimensionally) enough, or too much wick for the channels it fits into?" Is this wick too heavily or too lightly wrapped - is the density such that, capillary action is sufficient to feed the coil, but not drown it?"
I mentioned earlier that some advanced RTAs (may) use the same physics as a $5 clearo. The Squape, Taifun GT, Ithaka, Fogger V's, Aqua and even the latest greatest GUS Estia, along with their clones and variations, all fall into this category to one degree or another... with their wicks exposed to the juice tank. This isn't a bad thing, if done correctly, it works well and consistently.
A Kayfun, as well as it's variations and clones, use the pressure differential concept, but without the wick functioning as a seal. Instead we use the method of "controlled orifice" juice passageways - and a neat balancing act known as a "boundary layer" - which is established by those specific orifice sizes, keeping the juice from flooding the atomizer chamber.
In this application, juice is fed in liquid form, all the way into the atomizing chamber, before it encounters the wick.
With some lower priced KF clones, where the design is copied but not understood, and the orifice passageways are not considered "important"... you may find a condition of perpetual flooding or dry hits, from those orifices being too large or small.
The wick can act as a sponge... where with lower priced clones, they may have overdone it a bit on the orifice dimensions - and so those atomizers may need more wick than the original to stay in balance.
I suspect that the designers of the Kayfun (and Russian) spent more time fine tuning this aspect than any other.
Even genesis tanks have a pressure differential, but due to the design of the (typically metal or ceramic) wick not really functioning as a transfer port seal... it's frequently very temporary, unless the re-builder is very clever, in both their wick design and how that wick fits into the port it passes through.
Before this gets so long that no one wants to read it... I'll stop.
I used to teach this stuff - but in a different application. However, the same, sometimes complicated and really quite impressive "Bernoulli Principle" fluid dynamics apply, so... there you go, differential pressure is alive and well in your atomizer.
That's it... take it for what it is, do with it what you will.
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