Dear Peter in Auz
Thanks for the shout. >I think the nozzle of an oxygen-acetylene cutting torch is identical to a propane-oxygen ditto. The ring of small premixed flames serves to preheat the workpiece (steel) to a temperature where the central jet of oxygen can begin to burn, heat, melt and disperse the molten steel. They 'work' in the same way but the flame pattern is different. The Oxy-Acet has perhaps 6 holes and the propane-oxy has perhaps 10-20 little ones. There is a great picture of the two at http://www.cousesteel.com/AndysPlace/PropaneAcetylene.html That is the smallest number of holes I have seen for propane. And the shape is odd to. Usually the whole circumference is like a W bent around in a circle: wwwwwwww like that. The explanation about cutting and welding with propane is incorrect but the pictures are good. I am including a small portion of a zoomed photo from http://www.alibaba.com/product-gs/433428317/Cutting_Torch_Welding_Torch/show image.html The left part is a sleeve and the right part is the brass core. There are linear grooves cut perhaps 40mm long leading to the tip. The sleeve closes over the grooves providing a number of high velocity jets of propane around the central O2 hole. I think the reason for them is that the flame speed of the propane is higher than the acetylene and the increased velocity through small holes prevents flashbacks when hot. Starting a cut with propane is more difficult because of the higher velocity gas stream (more than double the air is needed) so localising the heating at the beginning is important. The multi-jet approach might assist that. Regards Crispin the (long suffering) welder
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