The hammering action of an impact wrench makes life easier when loosening stubborn nuts and bolts. Using one to tighten a fastener into position again at the proper torque is a bit harder to do. The amount of force applied by an impact wrench to the fastener depends upon the amount of air pressure available. While some manufacturers equip their wrenches with air regulators, many do not. In these cases, you have two options that will allow you to adjust the torque.
Turn on your compressor and allow it to run until it reaches its shutoff pressure.
Attach the impact wrench to the compressor with an air hose.
Reduce the working pressure available to the line by adjusting the pressure regulator on the compressor.
Attach the tool air regulator to the impact wrench.
Attach the air hose to the tool air regulator.
Adjust the tool air regulator to achieve the desired amount of torque.
Reducing the air pressure at the compressor reduces the amount of pressure available to all tools operating on the compressor. In a shop where several tools operate at the same time off one compressor, a tool air regulator is a better option. This operation will only reduce the amount of torque produced by an impact wrench. The maximum amount of torque delivered by your wrench is determined by the working pressure of your compressor and the tool manufacturer's pressure rating. In applications that demand narrow tolerances, check your settings with a calibrated torque wrench.
Never exceed the manufacturer's maximum recommended operating pressure for any tool. Always wear proper eye and hearing protection when working with power tools.