Techrite Controls Australia...
An 1807 Limiting Orifice Valve is used to set air/gas ratio on a nozzle-mix burner. It has a V-port plug that can be adjusted sensitively and accurately with a screwdriver. Turning the screw counter clockwise increases flow. A cap conceals the adjustment and discourages tampering with the setting. If an adjustment is needed, replace top cap on valve body to reduce air or gas leaks. The V-port adjustment is in a removable gas cartridge assembly, simplifying inspection or replacement. 1807 Valves have brass internals; 1807- -K Valves have iron internals for coke gas and others corrosive to brass; 1807- -TK Valves are for hot gases.