Running rich
Running rich turns up in 2 fields: heat treating, boilers. Here is what it means to the people in each one.
Running rich in heat treating
Shop talk for a furnace atmosphere carrying more carbon than its setpoint and heading toward soot.
Said of an endothermic or carburizing atmosphere whose carbon potential or enriching gas flow is higher than intended. Symptoms are a sooty, yellow effluent flame, black parts and climbing surface carbon, which leads to retained austenite and carbide networks. The opposite, running lean, risks low surface carbon and decarb.
"Effluent flame's yellow and smoky, she's running rich, back the natural gas down before the parts soot."
Running rich in boilers
Burning with too much fuel for the air available, so combustion is incomplete.
A rich burner shows low O2, rising CO, a lazy yellow flame and eventually soot. Causes include high gas pressure, a slipped linkage, a dirty fan wheel, a blocked air intake or a hot-day drop in air density. The opposite, running lean, wastes heat with excess air and can make flames lift off the burner. Rich is the more dangerous side, because CO builds quickly.
"It's running rich at low fire, 0.8 O2 and the CO's climbing, open up the air on the first cam screw."