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MAPP gas

Started by EllaBee, March 29, 2015, 04:49:03 PM

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EllaBee

Hi all,

I know this is a really basic question but I have been scouring the page for answers and can't find them.....when I use a diposable propane 400g canister my HH runs (albeit not as hot as the MAPP gas canister) fine, however when the MAPP canister is on it go's out within 30 seconds of torching, the canister is not even that cold - certainly not frozen. I cannot make 1 simple bead without the thing going out at least 3 times......what is wrong with my hothead? I noticed that the valve at the top turns slightly to the left or right, should this be set in a particular place?

Thanks in advance for any advice you can give

Carla

flame n fuse

Hello
Not sure if I can help, but by the 'valve' do you mean where the torch is screwed into the gas canister? this ought to be screwed in tight,with no movement. I haven't used it for ages, but I remember the torch was a bit tricky to light - if the gas flow was too high it would blow itself out. The brass knob (c 2 cm diameter) which rotates for increasing / decreasing the gas flow shouldn't wobble. The canisters get used up alarmingly quickly. I used to weigh mine so that I could work out how much was left. I think when full they weigh about 853 g, so an empty one will weigh about 450 g.
hope this helps!
Julia

cbeadies

#2
I haven't used Mapp gas but I know some people on here have had difficulties with it. I wonder if the cold weather is the problem, even if it doesn't seem 'frozen' perhaps it is cold enough to slow it down. Some folk recommend ways of warming it slightly, in these threads for example..
http://www.frit-happens.co.uk/forum/index.php?topic=29585.0

http://www.frit-happens.co.uk/forum/index.php?topic=22989.0

If you put 'mapp' in the search box from the home page (make sure you are logged in first) you should find a few more threads on this topic.

Hope you get sorted soon, it's so frustrating when you just want to get going with making the beads!

EllaBee

Thank you both of you, I'm just going to stick to the propane canisters from here- it saves me £6 a canister too....I just didn't want to waste the MAPP one.

Dietmar

MAPP gas is a mixture of methylacetylene and propadiene. Due to the fact beeing just technical grade this mix contains small amounts of lower boiling compounds. These compounds are smaller molecules and they need les oxygen per liter than the main ingreadients. This means the gas-air-mix is thinner than optimal for a stable burning flame. The torch head has a fix ratio of gas/air intake and a smaller flame is more diluted in fuel than a larger flame. If a larger flame is not wanted you can block one or more of the holes for air intake.

Look for the color of the flame. If it's pure blue or with a slight purple hue it is neutral or oxidizing. A reducing flame gas a slight turquoise or greenish hue. These colors help to see where in the possible range of stable flames your torch is burning.