... equipment, the basic procedure is to set the proper gas flow to the torch with the regulators, crack open the valves on the torch, light the flame with a friction-sparking lighter and then adjust the ... utilizing arc or MIG welding equipment.2-9 Haynes Welding Manual There are two basic types of arc-welders, relating to the polarity of the elec-tricity they produce, AC or DC. The DC machines are ... gas welding, where you haveto operate the torch with one hand while feeding the filler rod with the other hand,there is only one piece to control with arc -welding, the rod-holder. However, the rod...