Gas supply for a plasma arc material processing system

A computer-implemented method for reducing wear on a nozzle in a gas-cooled plasma arc torch of a plasma arc material processing system, the method comprising:

• selecting, by a gas selector valve, a non-oxidizing gas for supply to the plasma arc torch via a torch lead;
• initiating, by the plasma arc torch, ignition of a plasma arc using the non-oxidizing gas during a pilot arc mode for operating the plasma arc torch;
• automatically monitoring, by an arc monitoring device, at least one operating parameter of the plasma arc torch to detect when the plasma arc is transferred to a workpiece to process the workpiece in a transferred arc mode for operating the plasma arc torch;
• automatically switching, by the gas selector valve, an oxidizing gas for supply to the plasma arc torch via the torch lead once the arc transfer is detected based on the monitoring;
• and
• switching, by the gas selector valve, back to the non-oxidizing gas upon detection of initiation of ignition of another plasma arc by the plasma arc torch.

A gas supply system for a gas-cooled plasma arc material processing system, the gas supply system comprising:

• control means for controlling pressure of a gas supplied to a gas-cooled plasma arc torch in the plasma arc material processing system;
• selector means for selecting the gas from one of at least two gas supplies for conduction to the plasma arc torch via a torch lead, the selector means located upstream from the torch lead, the control means, and the plasma arc torch;
• a monitoring means configured to monitor at least one operating condition of the plasma arc torch;
• and
• a switching means operably connected to the selector means, the switching means configured to manipulate the selector means to supply the gas from one of the at least two gas supplies to the plasma arc torch via the lead based on the at least one operating condition of the plasma arc torch from the monitoring means.