Liquid cooled plasma arc torch system and method for replacing a torch in such system

A cap for use in a plasma arc torch system having a plasma arc torch removably mounted to a torch receptacle and a cooling system including (i) a liquid storage tank, (ii) supply and return lines providing fluid communication paths between the tank and the receptacle, (iii) a pump for pumping liquid from the tank through the supply line, the receptacle, the torch, the return line and back to the tank, the cap comprising:

• a base section insertable into an orifice formed in a top surface of the tank;
• a flange section integral with the base section and having a larger diameter than the base section;
• and
• an inner section surrounded by the base and flange sections and having at least one passage extending therethrough for passing pressurized gas and thereby maintaining atmospheric pressure in the tank.

A method for cooling a plasma arc torch removably mounted to a torch receptacle, comprising:

• providing a storage tank which includes a cooling liquid;
• providing supply and return lines between the tank and the receptacle;
• directing liquid from the tank through supply line, the receptacle, the torch and the return line for cooling the torch;
• returning liquid to the tank through a valve having an input port and a nozzle extending from a valve body and in fluid communication with the tank, at least a portion of the nozzle being disposed at an angle of greater than zero degrees relative to a horizontal axis extending through a center of the input port and the valve body, the returning step including passing liquid through the nozzle toward an inside top surface of the tank.

A method for removing a plasma arc torch removably mounted to a torch receptacle in a plasma arc torch system having a cooling system including (i) a liquid storage tank, (ii) supply and return lines providing fluid communication paths between the tank and the receptacle, (iii) a pump for pumping liquid from the tank through the supply line, the receptacle, the torch, the return line and back to the tank, the method comprising:

• turning off the pump;
• passing pressurized gas into the supply line to force liquid from the receptacle, torch and return line into the tank, thereby substantially clearing the receptacle, torch and return line of liquid;
• and
• removing the torch.

A method for changing a plasma arc torch removably mounted to a torch receptacle in a plasma arc torch system having a cooling system including (i) a liquid storage tank, (ii) supply and return lines providing fluid communication paths between the tank and the receptacle, (iii) a check valve coupled to the supply line, and (iv) a pump for pumping liquid from the tank through the supply line, the receptacle, the torch, the return line and back to the tank, the method comprising:

• turning off the pump;
• directing liquid through an orifice in a flow restriction member, which provides a fluid communication path between the supply and return lines upstream of the check valve, to equalize a pressure in the supply line with atmospheric pressure;
• passing pressurized gas into the supply line to force liquid from the receptacle, torch and return line into the tank, thereby substantially clearing the receptacle, torch and return line of liquid;
• and
• removing and replacing the torch.

A cooling system for use in a plasma arc torch system having a torch removably mounted to a receptacle, comprising:

• supply and return lines providing fluid communication paths between a liquid storage tank and the receptacle;
• a pump for pumping liquid from the tank through the supply line, the receptacle, the torch and the return line;
• and
• a valve including a valve body having an input port coupled to the return line for receiving liquid therefrom and a nozzle extending from the body and providing a fluid communication rerum path to the tank, at least a portion of the nozzle disposed at an angle of greater than zero degrees relative to an axis extending through a center of the input port and through the valve body.