Oxy/Acetylene torch usage

Recently, I purchased an oxy/acetylene torch to use for melting gold that I have purified using AR and dropped with SMB, then re dissolved with Acid/Bleach and dropped with oxalic acid. The torch came with a rosebud tip, but no instructions. I don't know what pressures to set the oxygen and acetylene to. Right now, I can only guess the acetylene should be between 3 and 5 psi and the oxygen should be between 20 and 25 psi. Am I in the ballpark, or do I need to make further adjustments?

Thank you in advance.

Hey...
You are at a good starting point with presures...
TEST it... take a bowl and put some baby powder in it or similar powder and practice heating without blowing it out of the bowl...

Make adjustments as your experience dictates....
The gages sound about right range wise... 20lb O2 and about 7lbs Acet.
Now on the handle you should have knobs to fine tune the flame...
Blue is Hot as heck while yellow gives soot.
For small stuff you don't need a full roaring burn everything flame. The less O2 you use, the less blowing you have...Pressure out of the tip...
Hope this helps..

BS.
Remembering the days when I'd melt a car before starting it a fire...

use the valves on the torch. turn on the fuel and light the torch. open the oxygen enough to turn the flame blue. adjust the flame to where the blue flame is very gentle with very little noise. it doesnt take extreme heat from a torch to melt gold. there should be two parts of the flame. a light blue flame that big and long and then theres a small darker blue flame right near the metal. adjust the dark blue flame as long as possible without a flameout. this is a reducing flame rich in fuel and lean on oxygen. if you have it adjusted right, the flux will turn black when melting and then clears when the dish turns red.

For all oxy-acet torch use EXCEPT FOR CUTTING the pressures should be roughly equal. 4-4 to 6-6 for a 0-1-2 heating tip. Maybe a little higher 8-8 if you have a big fat rosebud tip (which could cause you problems...you want a smaller one) or a 3-4-5 heating tip of large size. It is (only) when you are cutting that you want the higher oxygen pressure which is applied through the secondary valve, the lever on the cutting head. Some folks, kadriver comes to mind, use the cutting head but do not use the high-pressure cutting lever. He only uses the "pre-heat" aspect of the cutting tip, thus, in effect, he is using a mini-rosebud tip. Sometimes a real full-sized rosebud tip will be too powerful for a small melting dish and have a tendency to blow your charge away. ANY tip must have at least enough pressure/flow to prevent pre-ignition of acetylene. Big pop. Got check valves on your torch lines? Got chains holding up your tanks? Important safety stuff.

Thanks all. The instruction which came with the torch listed pressures for gasses when cutting, but didn't mention pressures for the rosebud tip. Now I have somewhere to start.

Please please PLEASE heed element47.5's safety warnings. It sounds like you are new to the oxy/acetylene rig (congratulations on getting one by the way!) Spend some time using it on stuff you don't care about. Even experienced users will get the occasional POP. Be sure you have nice clean components before you start a melt. You could lose a large portion of you hard work with an improperly set or dirty piece of equipment. Good luck! Looking forward to seeing your button

Today my old man gifted his old welding rig to me. Maybe I should invest in some new hoses sooner or later.

Are all necessary safety valves/flashback arrestors present?

Which of the tips would probably be the best for melting 1-10g amounts of goldpowder?

Can I use those tips succesfully with propane/butane and oxygen instead of acetylene and oxygen?

Thank you for any hint!

It can only flashback if there's oxygen mixed in with it and this usually happens at lower gas pressures/velocities. Keep your tips clean, as the acetylene will soot up. I really think propane is preferable--you can still carbon black your molds but it's less dangerous than acetylene. Remember, no tape on the CGA fittings.

You want to use the lowest flame possible to sinter and partially melt the gold to form a crust, then work your way around the sides until it all melts. Don't overheat the gold and wear safety glasses with a slight tint, especially if you're using borax. If the gold is pure, it should melt pretty quickly and with no scum and leave nothing more than a light purple glaze.

I usually like to spray smaller crucibles for gold/silver melting with a spray bottle containing a teaspoon of carbonate (to help the borax stick and glaze) and 5 tablespoons of borax to two pints of distilled water. Bake it, then take the torch to it and glaze the surface, then melt your gold.

Melt your pure gold/silver with a neutral flame; excess oxygen and the silver will be crabby and the gold, if not highly pure, will discolor.

Lou said:

I usually like to spray smaller crucibles for gold/silver melting with a spray bottle containing a teaspoon of carbonate (to help the borax stick and glaze) and 5 tablespoons of borax to two pints of distilled water. Bake it, then take the torch to it and glaze the surface, then melt your gold.

Click to expand...

That sounds like a neat trick Lou! That's the first time I've read that one.

Dave

Ive got 2 torch setups here at home,
Others at a shop at a friends.
One is a standard H/D Victor & the other is a mini jewelers oxy/Ace setup that also has the adjustment valves on the torch handle just is tiny in size. Safety here is the main issue im getting at since the OP stated he has no instructions, Ill set forth a few. Both setups I have Ive placed the tanks in a poly case so no way can they fall over accidently but even a dolly with straps will do on larger tanks & I have the poly cart strapped to a dolly for easy movement about, also on both. next thing is do not even consider to use a torch that also uses Oxygen unless it has check valves AND flashbacks on the regulators period. One note, always, always start the flame using the gas fuel first THEN turn on the Oxy. Do the reverse when turning the torch off, Oxy first then the gas.
Also, so you do not damage the regulators diaphragms slightly open them BEFORE opening the main tanks, otherwise damage may occour to the regulators. Keep the torch handle valves closed when doing all this then, at the point your ready open the Ace handle valve & let it run till you smell gas then shut down the valve. next open the Oxy just for a sec or so to purge that line then also close the valve, now you are ready to ignite the Ace & adjust the flame. Turn the gas down till it stops smoking than slowly add Oxy & adjust both for a neutral flame, that is a nice pencil point blue flame within a outer flame. If it pops you set the torch vale too low or your too close to your work. The torch head will dictate the pressure needed, smaller means less pressure such as on my jewelers torch which only requires 1 or 2 lbs pressure, the regular standard torch will use 4-6lbs on the Ace & 8-11lbs on the Oxy for say a #6 tip size. Unless your melting a huge amount a smaller tip will be better since the blow pressure is much less, intense heat not pressure is what you want that is why I like the mini jewelers torch so much for PM recovery projects. Reaches over 6,000 degrees with a tiny flame & uses almost no fuels. Well worth buying one over a conventional torch IF your only using it for PM use. You can get a nib jewelers torch setup on Ebay for about $60 complete with several tips & the mini 1/4" hoses that do hook up to a regular regulator.

I weld with a mig & an arc & the Ace/Oxy, all have their particular usefulness, mig is nice due to minimual sparks & really solid hard weld, can almost weld in a teeshirt also. Arc is fast & dirty but fast, gas is nice for melting & heating things. Best of luck & if nothing else download a manual & get those flashbacks & checkvalves ASAP if you do not have them. Some torches have built in check valves but the flash backs attach at the regulators then to the hoses.
I hope ive helped from a safety standpoint.



Dave

i use the oxygen acetylene setup for assaying and melting and a size o gas welding tip works nicely for both applications