In the lower end of the valve is a hole to prevent the burner going out if valve is entirely closed. This hole must not be enlarged.
The valve adjusting screw is slotted and has a setscrew inserted through the valve lever to keep the adjusting screw from turning. Between the head of the adjusting screw and under part of the lever is a spring which forces the head of adjusting screw against the cap of the valve. When tightening up on the adjusting nut the spring closes, releasing some of the pressure on the valve, permitting more gas to pass the valve. By loosening the adjusting nut the spring expands, forcing the valve down, cutting down the flow of gas to the burners.
To adjust thermostat, if metal is not hot enough, raise the adjusting screw by turning the adjusting nut farther down; if the metal is too hot, unscrew adjusting nut, allowing the adjusting screw to force the valve farther down.
The screw in the top of the expansion rod is for the purpose of making the rod longer, should occasion require. Do not change this screw unless necessary.
There are two sets of rods and valves on the regular equipment. One set regulates the gas to the pot burners and the other regulates the gas to the mouthpiece burner. Experience has shown that it is impractical to regulate the mouthpiece from the crucible, so cut off this part of the regulation and use a gas burner cock.
ELECTRIC POT DEFINITIONS
The circuit is that part of the equipment such as copper wires, resistance wires, switches, etc., which is intended to carry electric current. They are all insulated from the frame of the pot.
The current is the electricity passing through the equipment.
Amperes is the volume of current passing through.
Volts is the strength or pressure of the current.