Why is my oxy torch buzzing?

[Screwdriver]

I just set up a new (to me) oxy acetylene kit. Murex saffire 5 torch with number 5 nozzle. Six metres of hose fed from new flashback arrestors and almost full oxy acetylene tanks.

When I fire it up the torch buzzes a bit like water banging in taps. Then it goes away but comes back.

My first time with this setup. What sort of pressures should I be setting at the regulators? I assume this is where I am going wrong.

S.

 

[rory1]

Rough rule of thumb that I use is 5psi acet, 50 psi oxy.

Open the acet just a little and light it, then open it up until the black soot disappears before adding the oxy.

 

[Bill Edwards]

I think the OP is using a welding/brazing torch, not cutting!

Try 4 or 5 psi for both gasses. Never, ever exceed 15 psi on acetylene as it can become unstable. I don't think I've ever needed more than 5 even for cutting.

You should be able to open the acetylene valve fully on the torch and have the flame burn clean (no soot) but without jumping away from the nozzle, then add the oxygen. Turn off the acetylene first when extinguishing the torch.

 

[Kent]

Just check you haven't got something that's gone back up the nozzle in use and give it a clean with the right size cleaner as a double check

 

[gordon stephenson]

I was always taught, and it worked for me, that the Acet pressure for gas welding was "rule of thumb" set PSI the same as the nozzle size, and OXY a little higher,

 

[pedrobedro]

Turn the acetylene reg to about 5 psi and the oxygen to similar then when you light the acetylene flame turn the torch knob till it just stops sooting then open the oxygen slowly till you get the flame you need. You could open the torch knobs fully and set it with the regulators but if you change nozzles often you have to do it again every time.

 

[gordon stephenson]

Just out of interest what are you welding with a Number 5 tip?

 

[Screwdriver]

Thanks for the tips. I think I had it set way too high.

I'm not welding anything yet, just fired it up to see if it all works. I have a set of 2, 3, 5, 7 and 10 nozzles iirc. Not sure yet which nozzles are suitable for which materials. I picked 5 first because it was in the middle! A guide for nozzle selection would be very handy.

S.

 

[Sarto]

Hi.
In the following link (page 7-17) there is a table with suggested settings for the various
welding nozzles.

http://thermadyne.com/IM_Uploads/doclib_8063_DocLib_4119_0056-0138.pdf

But I don't know if they are universal or equipment specific.

SARTo

 

[sardine]

Pretty sure that buzzing happens when the gas pressures are too low for the nozzle.

 

[gordon stephenson]

For car bodywork metal thickness i always used a number 2 or 3,

 

[brightspark]

no 2 and 3 cover most aplications for welding. any thicker than that and u can arc weld unless u use them for heating things up

 

[backpurge]

Important to match your working pressures to the nozzle size, one of the biggest causes of flashbacks is not having a properly balanced flame

 

[Screwdriver]

Points taken, many thanks. I'll fit the number 2 and double check on the flow rate. I'll also do a proper leak test etc.

S.

 

[Screwdriver]

Wow. I made a number of (huge) mistakes! didn't open the valves when setting flow rate so that was pretty much maxed out. Have ordered some number ones for general use. Looks like my setup is gas tight because when I forgot to bleed the hose (!) next day it was still up to pressure. I did remember to close the bottle valves.

Anyhow, I found this on YouTube which for me as a beginner, is I think, excellent.

Never mind the slightly dodgy hat.

S.