Is the resistance change in square SS wire different than round wire?

[bombastinator]

so I got some .3x.3mm square sectional SS wire that was sub marked as being equivalent to 28ga because squares have a higher surface are to mass ratio than circles, and wrapped some simple spaced coils with them. The total resistance was higher than expected and I’m seeing a big enough resistance v. heat fluctuation that it is tripping the “did you change your atomizer?” Type reactions on my mod. This stuff is not acting like 28ga.

Anyone know anything about this stuff? It’s not behaving like I thought it would.

 

[Fredman1]

The coefficient for a specific st st would stay constant, no matter the shape of it I would think.

 

[Mordacai]

I know that composition, manufacturing processes and metal aging could affect the resistance.

But it's people such as Professor Mark Miodownik, a materials technologist who could give a much better answer than I.

 

[ScottP]

so I got some .3x.3mm square sectional SS wire that was sub marked as being equivalent to 28ga because squares have a higher surface are to mass ratio than circles, and wrapped some simple spaced coils with them. The total resistance was higher than expected and I’m seeing a big enough resistance v. heat fluctuation that it is tripping the “did you change your atomizer?” Type reactions on my mod. This stuff is not acting like 28ga.

Anyone know anything about this stuff? It’s not behaving like I thought it would.

I think the problem could lie in the fact that there isn't just one SS. SS has a number associated with it (304, 316, 316L, etc.) that determines the specific composition and each one has a different coefficient. So when they say it's "equivalent" to 28ga SS, do they mean SS 304 or 316 or something else?

The coefficient for a specific st st would stay constant, no matter the shape of it I would think.

Correct. It should remain constant. This is why people have been able to use SS Clapton's, and other SS exotic builds with TC just fine. Which is why I suspect that SS square stuff may be some completely different version of SS.

 

[ArminF]

I found that SS 304 has a bigger difference than 316.
And if you start glowing slow (low wattage) and raise it while preparing your coil it stays a bit better at the end.

And a square deliver more material than a round wire. So here the resistance will change anyway to a higher value. Would guess 5-10 percent then after dry glowing the coil again 5-10%


V4A Stainless Steel Square Wire
Mat.Nr.: 1.4404 (X2CrNiMo17-12-2), AISI 316L
resistance: 8,3 Ohm/m ..... 2.5 Ohm/ft
width & thickness: 0.3mm * 0.3mm / 0.012" * 0.012"
Temperature Coefficient: 100

Stainless Steel Wire V4A
Mat.Nr.: 1.4404 (X2CrNiMo17-12-2), AISI 316L
resistance: 9.3 Ohm/m ..... 2.83 Ohm/ft
wire diameter: 0.32mm / 0.013" / AWG 28
Temperature Coefficient: 100


Stainless Steel Wire V2A
Mat.Nr.: 1.4301 (X5CrNi18-10), AISI 304
resistance: 9.1 Ohm/m ..... 2.77 Ohm/ft
wire diameter: 0.32mm / 0.013" / AWG 28
Temperature Coefficient: 105

Source:
Zivipf.de

 

[bombastinator]

Stuff claims to be 316L numbers I’m getting are weird. Coils together should be around .5 ohm according to my calculator. At first I was getting above 2ohm. Closer to 3ohm. Then I got a dry hit, reset the wick, and now it’s .36ohm. Neither is close to what I would expect. It was eBay wire. I couldn’t find square wire anywhere else. The company that makes it only sells on eBay and I made as sure as I could that I was buying from the actual company by following their link to eBay from their website.
When firing the coil immediately jumps to around 2.5ohm, so I think the .36ohm is some sort of measurement artifact.

UPDATE: removed and replaced atty to reset mod reading. Now I’m getting 2.35ohm which raises to 2.55 under load.
I’d normally assume only one coil is connecting, but both coils are showing heat and coil schmutz. Also both wicks blackened a bit. Even if only 1 coil is connecting the ohms should still be less than half what I’m actually getting though.

Trying it on a different mod I’m getting very similar readings.

 

[ScottP]

Stuff claims to be 316L numbers I’m getting are weird. Coils together should be around .5 ohm according to my calculator. At first I was getting above 2ohm. Closer to 3ohm. Then I got a dry hit, reset the wick, and now it’s .36ohm. Neither is close to what I would expect. It was eBay wire. I couldn’t find square wire anywhere else. The company that makes it only sells on eBay and I made as sure as I could that I was buying from the actual company by following their link to eBay from their website.
When firing the coil immediately jumps to around 2.5ohm, so I think the .36ohm is some sort of measurement artifact.

UPDATE: removed and replaced atty to reset mod reading. Now I’m getting 2.35ohm which raises to 2.55 under load.

Jumping to 2.5 ohms from either .36 or even .5 ohms sounds like something isn't making a proper connection. The heat coefficient of SS is 0.00088, which means that the resistance will go up by that amount per degree (Celsius) of temp change. To get a full 2ohm difference would take an increase of over 2200 degrees C (over 4000 degrees F) of heat. I can assure you, that is not happening.

What happens if you fire the base of the tank with the coil and wet wick but without the top part of the tank attached?

 

[bombastinator]

Jumping to 2.5 ohms from either .36 or even .5 ohms sounds like something isn't making a proper connection. The heat coefficient of SS is 0.00088, which means that the resistance will go up by that amount per degree (Celsius) of temp change. To get a full 2ohm difference would take an increase of over 2200 degrees C (over 4000 degrees F) of heat. I can assure you, that is not happening.

What happens if you fire the base of the tank with the coil and wet wick but without the top part of the tank attached?

Same. I can check failed insulator. It’s an aromamizer and I’ve got one remaining new unused deck for it. Would have to be a new coil set which makes things a bit unknown though

 

[ShamrockPat]

ALL Stainless Steel is an alloy. NO hard specs, just ranges. Generally 316 will raise ~20% in vaping range temps. And notice the 4xx series has the lowest maximum Nickel content.

 

[Punk In Drublic]

Coming from e-bay how do you know it is SS316? Mislabeled wire has hit the market in the past!

Modeling a 0.5 ohm coil but obtaining a 0.3 ohm coil tells me something is amiss – but not necessarily a problem. HOWEVER, reaching 2 to 3 ohms while firing from 0.3ohms is what I consider a large problem. You either have an issue with your equipment or build, which you should be able to identify and rule out with another build, or you are not using SS316 wire

 

[score69]

I would try a new build on a different atomizer and see if you get more reasonable results.

If you've tried it on different mods and gotten the same result, then me thinks something is amiss with the build, or the topper.