Temp Control and Kanthal

[djvanlandingham]

Hey forum! Hows everybody doing. I have but one quick question. I have been vaping for a few years now and Im really looking at a DIY box mod with the 200 chip. So why do you need a different wire for temp control? Why ss or nickel or ti? I really like what Im reading about temp control and would like to move into that type of vaping but would like to understand it a little more. Anybody got a quick primer on why Kanthal is not used in temp control? Thanks!

[Jalcide]

Howdy. Sure, so...

Some wire predictably changes resistance as its temperature increases (and decreases).

It's this changing resistance, that's measured many times a second, that allows the chip to throttle the energy hitting the coil so that it can match a desired temperature.

Wire that has a large change in its resistance as its temperature changes -- a higher TCR (Temperature Coefficient of Resistance) -- is good wire for this job.

The base resistance of the wire also matters (the higher the value the more accurate TC precision is), but let's ignore that right now to keep it simple.

The complexity of the math that describes the change (linear, curved, s-curved, etc.) also factors in, but we'll ignore this, too. 

Kanthal has a very low TCR; its resistance doesn't change much as it gets hotter or cooler. This is why it's a poor TC wire.

Not only would the chip need to be extraordinarily sensitive to detect the changes, but the rest of the electrical connections in the mod and atomizer would need to be in a near laboratory setting; gold plated connection, etc.

So, kanthal is at the bottom of the TC precision list.

Nickel has a very high TCR, but also very low base resistance, so it's a great TC wire, but actually not the best theoretical wire for TC.

Titanium is in the sweet spot of having a high TCR and also fairly high base resistance and some consider it the best for TC.

I think the best wire, in theory, is 430 SS, once you factor in the base resistance and TCR. It ends up having the highest TC precision value.

In practice, I don't know if this works out to be true. I have some 430 on order, but haven't been hands on with it yet.

My feeling right now is that Titanium probably is the most accurate TC wire, followed by Nickel, followed by SS.

[djvanlandingham]

Ok I now understand and that answers my question so thank you! I have read a lot about wire and I seem to get the ideal that SS is the safest out now. Anybody have input on this?

[Jalcide]

The only real info I've seen seems to suggest that not much of any of these alloys is ending up in the vape.

https://www.youtube.com/watch?v=Cvb4Wzf_xyk

The toxic Nickel compounds people talk about, don't occur at these temps or oxygenated conditions.

Titanium Dioxide -- "nano" versions of it -- the main worry -- also are not created under vape conditions.

I don't know the real answers and I don't think anyone does, but I suspect the safety looks something like this (my guesses from safest to least safe):

Titanium (because it's so very inert and is used in medical implants).
Stainless Steel (because it's so non-reactive and also used in medicine, food prep and cooking)
Nickel (because it's run via temp control and is keeping the overall vape safer)

These are just my feelings. Vape at your own risk. It's certainly not risk free.

But I worry about what's created from VG, PG and flavorings way more than the wire.

[Jaquith]

Jalcide said:

...flavorings way more than the wire.

Yep, flavorings are the real culprit. PG, VG and Nicotine have been studied for years being inhaled. You do have long-term leaching issues with alloy metals (wires); eg Ni200, SS3XXX, etc. I try to avoid metals with Nickel, Aluminum, Chromium, etc. Titanium Grade 1 is by far by favorite wire; it's biocompatibile meaning it doesn't penetrate the cellular membrane nor react on a cellular level. The "bad" form of TiO2 is formed commercially and in a acidic bath, not the larger nanoparticles formed on a super heated (>2,100° F) wire. Wires with a higher TCR, eg Titanium, are more accurately temperature controlled; (Resistance, Temperature) changes are greater and therefore more easily and accurately regulated. Probably the best metal might very well be Platinum or Titanium with a Platinum coating (TiPt). Platinum is a nontoxic, noble metal which doesn't oxidize. However, at $50-$70 per coil is exceedingly cost prohibited for most people.