MIG Regulators FAQs
Straight answers to the questions people ask most when choosing and using regulators for MIG shielding gas.
What does a MIG gas regulator do?
A regulator reduces the high pressure in the gas cylinder to a low, steady working pressure, and lets you set the flow that goes to the welding torch. Without it the gas would come out far too fast and the pressure would change as the cylinder emptied.
A steady, correctly set flow gives a good shielding gas cover over the weld pool, which protects the weld from the air. Too little gas lets air in and gives porous welds, while too much wastes gas and can cause turbulence that also draws air in.
How do I read the gauges or flow meter?
Many regulators have two gauges. One shows the pressure in the cylinder, which tells you roughly how much gas is left, and the other shows the outlet setting, often marked in litres per minute. Others use a tube with a floating ball to show the flow.
Flow scales are made for particular gases and conditions, so use the scale that matches your gas and read a flow tube at the point on the ball the maker shows. Treat the figure as a guide. If you want to know the true flow, measure it at the nozzle. Check your manual for how your own regulator should be read.
How do I fit a regulator safely?
Check that the regulator and its connection are clean and undamaged and are the right type for the cylinder. Briefly open and close the cylinder valve before fitting to blow out any dirt, then fit the regulator and tighten the connection firmly with a suitable spanner, without forcing it. Keep oil and grease away from the fittings.
Open the cylinder valve slowly, and check every joint for leaks using leak-detection fluid. Close the cylinder valve at the end of the day. Never use damaged regulators or repair them yourself.
Why does my gas run out quickly or the flow drop?
Leaks are the most common reason, so check every joint, hose and the regulator with leak-detection fluid. Other causes are leaving the gas flowing between welds, setting the flow too high, and a blocked or restricted nozzle or diffuser.
With carbon dioxide, a high flow can also cool the regulator enough to freeze it, which reduces the flow. A heater between the cylinder and the regulator prevents this. Turn the cylinder off whenever you finish welding.