Is that “whoooshhhh” sound the start of gas shielding pre-flow, or is it the sound of flushing money down the drain?
Unfortunately, it’s probably the latter, as gas surges during arc start are a common – yet accepted – problem in many welding operations.
After the solenoid valve on the welding machine or wire feeder closes, gas pressure in the hose continues to build up until back pressure stops the flow of gas. The gas hose may even expand a fraction of an inch. Like pinched fingers releasing a swollen balloon, the next opening of the solenoid valve allows a blast of compressed gas to exit the MIG gun or TIG torch at 80 to 120 CFH (2265 to 3398 l3/min) or more (Figure 1). As we’ll discuss later in this article, more is not better when it comes to gas flow.
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