Let's go on with the new vaping hype: the temperature control and the DNA40.
Before these flamboyant mods other alloys and metal for coils were used to make coils, out of the usual suspects: Kanthal type A-1 and nichrome. The DNA40 has introduced us a new actor to the scene: pure nickel (99,99% and commercially named Ni-200).
It has been said that could pose some risks if it is managed at high temperatures. Anyway, the vaporization process to get an aerosol or spray over 400 ºF surely poses a serious risk of getting harmful decomposition chemicals, mostly from the dehydration process of VG and PG, which everybody fears. That's a bit over 200 ºC, if you've got a next-gen DNA40 with Celsius arrangement.
Before these flamboyant mods other alloys and metal for coils were used to make coils, out of the usual suspects: Kanthal type A-1 and nichrome. The DNA40 has introduced us a new actor to the scene: pure nickel (99,99% and commercially named Ni-200).
It has been said that could pose some risks if it is managed at high temperatures. Anyway, the vaporization process to get an aerosol or spray over 400 ºF surely poses a serious risk of getting harmful decomposition chemicals, mostly from the dehydration process of VG and PG, which everybody fears. That's a bit over 200 ºC, if you've got a next-gen DNA40 with Celsius arrangement.
About nickel toxicities, it might be said it is utilized on surgeries. Some people are allergic to nickel and its compounds, but apart from that... we've been using alloys that, if you ask me, could be even less safer than nickel alloys.
Nichrome, as its name suggests, is an alloy formed with nickel and chromium. This alloy is even more resistant to chemical attack than its components alone. What is more, it has interesting properties in the field of thermal exploitation, like kanthal. As a matter of fact, it is less likely to be corroded by humidity and PG/VG at moderate temperatures, if it is compared to kanthal. Its ability to withstand corrosion makes possible its use as a cheaper alternative to platinum (one of the most chemical resistant metals) in microbiology (seed of bacteria over Petri dishes) and in the chemical laboratory. If money is a serious constraint, or fluoride compounds are involved (they eat platinum...), platinum hardware is inconvenient and nichrome is preferred.
Almost all food industry uses pure nickel and some of its alloys for high temperature boilers involved in evaporation and condensed extracts, as it is corrosion-resistant. At less temperature stainless steels of high food grade (AISI 316L/Ti) are preferred, but that is because of costs, and those steels are, in fact, alloys of iron with chromium and molybdenum/nickel in several degrees. In the non-food chemical industry they can get the luxury of pure titanium and its alloys, but usually this happens only in big petrochemical manufacturings. A Kg of pure titanium of chemical grade for tubing costs a lot!
Nichrome, as its name suggests, is an alloy formed with nickel and chromium. This alloy is even more resistant to chemical attack than its components alone. What is more, it has interesting properties in the field of thermal exploitation, like kanthal. As a matter of fact, it is less likely to be corroded by humidity and PG/VG at moderate temperatures, if it is compared to kanthal. Its ability to withstand corrosion makes possible its use as a cheaper alternative to platinum (one of the most chemical resistant metals) in microbiology (seed of bacteria over Petri dishes) and in the chemical laboratory. If money is a serious constraint, or fluoride compounds are involved (they eat platinum...), platinum hardware is inconvenient and nichrome is preferred.
Almost all food industry uses pure nickel and some of its alloys for high temperature boilers involved in evaporation and condensed extracts, as it is corrosion-resistant. At less temperature stainless steels of high food grade (AISI 316L/Ti) are preferred, but that is because of costs, and those steels are, in fact, alloys of iron with chromium and molybdenum/nickel in several degrees. In the non-food chemical industry they can get the luxury of pure titanium and its alloys, but usually this happens only in big petrochemical manufacturings. A Kg of pure titanium of chemical grade for tubing costs a lot!
Having said all this 'brief introduction' about uses and dangers, let's get to the point. We were talking about DNA40, weren't we? It uses nickel (Ni-200) because precisely with that material it has been calibrated by Evolv engineers to get temperature control with less than 10ºF of error. Or less than 5 ºC....
The variation of resistivity with temperature for Ni-200 is very well known, and it is easy to reproduce in all the world. More important, it is not a flat response curve, that is, it changes with temperature, opposed to kanthal and nichrome, which happens to show an almost flat curve. They do not change enough their resistivity in order to get accurate temperature readings.
It seems that Evolv has confirmed to some DNA40 users that a basic rule of thumb to manage non-nickel coils, like titanium coils, would be setting the temperature control set-point at half the normal, nickel-based, set-point. Well, it might be possible, but we will stay out of the calibrated curve stored in the chip, thus generating bigger errors in the measurements. Even though the number we put as set-point should not be crucial, if it is well set by trial and error ensuring a zero tolerance in the generation of thermolysis by-products we will gain full control about what matters, and for that we have the best 'quad pole mass detector chromatography analyser': our taste buds.
Following this very same rule, any metal or alloy that could be suitable to wind coils (that excludes lead!) and without a flat resistivity curve with temperature will serve us, just testing the good set-point. But the flat curve thing excludes kanthal, nichrome, and more exotic alloys like monel and inconel. Iron? Why not? Silver? Probably.
Think of kitchenware, like pans and pots, exceptuating aluminum ones because it has a low melting point, with high volativities, and we might have a go. Aluminum is pyrophoric (it burns with air if its powdered, often rendering explosions), but titanium also is .... both will burn, even being wires, if the flame applied is hot enough.
Surely Ni-200 should suffice, should not it?
Just to end, kanthal alloys have a significant percentage of aluminium, in a safe state as it is effectively alloyed. But if Alzheimer's disease rings some hysterical bells, let me remind you that the early association between aluminum and Alzheimer's has been refuted. The first study was compromised by the use of aluminum trays to move the brain tissue samples of deceased people... the aluminium contents were out of this world and utterly exceptional. When they used stainless on the trays, not so surprisingly, the aluminium contents were more palatable.....
But this does not mean that we should forget it. I can live with aluminium in my food containers (unless I'm a cave man), but I cannot cope with heated aluminium on my vaping hardware..... not sure of what is worse.....nichrome, kanthal? If corrosion factors enough to think twice about it, probably I would stay with nichrome......
But kanthal has better (higher) resistivity and it been said it is easier to work with it....
