Nozzle
Nozzle turns up in 2 fields: thermal spray, boilers. Here is what it means to the people in each one.
Nozzle in thermal spray
In a plasma gun, the water-cooled copper anode the arc attaches to; in HVOF, the passage that shapes the jet.
In plasma spraying, the nozzle is the anode: a water-cooled copper part, often tungsten-lined, through which the plasma exits and to which the arc attaches. Arc erosion roughens its bore over time, causing unstable voltage, buildup and spitting, so nozzles and their matching tungsten cathodes are changed on a fixed arc-hour schedule. In HVOF and cold spray guns the nozzle is the converging-diverging section that accelerates the gas.
"Nozzle bore is pitted right at the arc root, swap it and the electrode together before the next lot."
Nozzle in boilers
The precision tip on an oil burner that atomizes oil into a fine cone-shaped spray, rated in gallons per hour.
Each nozzle is stamped with its flow rate in gallons per hour at 100 psi, spray angle such as 60 or 80 degrees, and pattern: hollow, solid or semi-solid. Raising pump pressure raises flow, so a 1.00 GPH nozzle fires more oil at 140 psi. Nozzles are replaced at every annual service because worn or partly plugged ones give poor spray, smoke and soot.
"Burner calls for a 0.85 80 degree hollow nozzle, somebody put in a 1.25 solid and wondered why it soots up."