Barrel
Barrel turns up in 3 fields: thermal spray, HVAC, fiber optics. Here is what it means to the people in each one.
Barrel in thermal spray
The long tube on an HVOF or detonation gun where particles are heated and accelerated before exiting.
Extension of the nozzle on HVOF guns, and the full firing tube on a detonation gun, where gas and particles travel before leaving the gun. Barrel length controls dwell time and particle speed: longer barrels give faster, hotter particles. Molten material can build up inside a worn or overheated barrel and break loose as spits, so barrels are inspected and replaced as consumables.
"Put the 6-inch barrel on for the carbide, the short one won't get the particles fast enough."
Barrel in HVAC
Shop name for a chiller's shell-and-tube evaporator or condenser vessel.
Water runs through the tubes and refrigerant fills the shell, or the reverse, inside a long cylindrical vessel that looks like a barrel. Chiller techs talk about the evaporator barrel and the condenser barrel, pulling heads to brush tubes, and the danger of freezing the barrel when flow is lost while refrigerant temperature is low. A frozen barrel can split tubes and flood the refrigerant circuit with water.
"Lost chilled water flow and the low temp cutout was set too low, we froze the barrel and split six tubes."
Barrel in fiber optics
Installer slang for a fiber adapter, the double-ended bulkhead part that joins two connectors.
A small housing with a connector receptacle on each side and an alignment sleeve inside that centers the two ferrules. Singlemode adapters use zirconia split sleeves; the housing color follows the connector: blue UPC, green APC, beige multimode, aqua for laser-optimized multimode. Barrels snap into patch panel plates, and a worn or dirty sleeve adds loss to every connection made through it.
"Grab a couple of LC barrels so we can join these two jumpers and get the camera link up until the panel shows up."