surface mix/premix

istandalone24/7 · #1 2012-07-27, 3:26am

i've just got a couple questions regarding the differences between a premix and surface mix torch.
i know about flame chemistries and how/why they do what they do and i know how to set them...with a surface mix torch that is.
my midrange/premix came in, and i've got no idea how to use the premix torch.
is there any sort of faq about the similarities/differences and when it's best to use premix or surface mix?

i know premix is good for concentrated heat, pinpoint flame if needed. good for fuming silver. very bad for soft glass also.

but when besides fuming and tearing boro tubing, is it a good idea to use the premix in place of the main burner??

also, what about candle length with this? it's the ox4 tip, and i'm running it on two m15 oxycons.

LarryC · #2 2012-07-27, 10:20am

Quote:

Originally Posted by istandalone24/7

i know premix is good for concentrated heat, pinpoint flame if needed. good for fuming silver. very bad for soft glass also.

My Surface mix Mirage does all of those things extremely well. Guess THEY don't know as much as THEY think, huh? I would just start using it and experiment with it. I never read instruction manuals

istandalone24/7 · #3 2012-07-27, 11:28am

i guess my main question is, do i look at the candle tip for flame chem? short blue for oxidizing, slightly unfocused tips neutral, and longer yellow tips reducing.

is this the same for the premix, save for it only has one candle of couse?

Dragonharper · #4 2012-07-28, 5:26am

A premix is like, actually is, a welding torch. A neutral flame will have a sharp focused inner cone with no yellow what so ever. After you achieve that you adjust for either reducing or oxidizing flame. A reducing flame may or may not have yellow but the inner cone will not be as well defined. One thing about premix, the hottest part of the flame is at the tip of the inner cone. AND you can work there and be assured that your flame chemistry is where you set it. Also with premix it is advisable to use flash back arrestors.

istandalone24/7 · #5 2012-07-29, 4:45am

THANK YOU. that's exactly the info i was looking for, thank you so much!!

i've got an fba on the propane side, on the oxycons no fba. i need one with oxycons?

Dragonharper · #6 2012-07-29, 12:59pm

No you shouldn't need an FBA for the oxy cons. The typical reasons that flash backs occur are: torch malfunction and more commonly, running the tank completely empty. In a premix torch the fuel is mixed inside the torch. If you let either the fuel or the oxy tank go completely empty it's possible for the flame to recede into the torch as the pressure diminishes, and then with the pressure from the remaining gas, to travel back the torch hose to the regulator and tank. While a flash back traveling beyond the torch is rare it can happen with serious out comes. This is why most welding text books advise against running your tanks completely empty. Besides the fact that it is damn inconvenient to run out in the middle of a critical operation.

istandalone24/7 · #7 2012-07-30, 5:35pm

used my premix for my first ever fume job, first ever boro marble over 1" too.
i'm pretty proud of it

cheng076 · #8 2012-08-02, 10:20am

Well done. Love the blue swirl effect.
PJH

istandalone24/7 · #9 2012-08-02, 1:39pm

thank you.

istandalone24/7 · #10 2012-08-17, 6:22am

my only other question at this time is, how long can i get the candle on the premix? is it safe to just crank it up as far as i can (when i need that much) until i meet the oxycon's limit, volume wise? any melted torch faces doing that?