Disc
Disc turns up in 2 fields: valves, farming. Here is what it means to the people in each one.
Disc in valves
The movable closure element that seats to stop flow in globe, check, safety and butterfly valves.
In a globe valve the disc moves straight down onto the seat; in a swing check it hangs from a hinge; in a butterfly valve it is the rotating plate in the bore; in a safety valve it is held on the nozzle by the spring. Discs may be plug-shaped, flat, ball-shaped or composition-faced. Gate valves call the same part a gate or wedge, and control valves call it a plug.
"Disc nut backed off the stem on that globe, so the handwheel turns but nothing's moving."
Disc in farming
The act of breaking up soil clods and crop residue using a tractor-drawn implement with steel blades.
Running a disc harrow over a field to slice up leftover plant material, break down large soil clods, and level the ground. It is usually done after primary plowing to prepare a smooth, fine seedbed before planting.
"We need to disc the north forty tomorrow so it has time to dry out before we drill the beans."