Definition
A gerb is a fountain with a directed, dense jet: a thick tube with a strongly choked outlet that projects a sharply defined column of sparks under pressure, like a blowtorch. The French word passed into English unchanged to designate these display jets. An outdoor gerb rises 3 to 15 m for 5 to 60 seconds; hung upside down it becomes the building block of a waterfall; mounted on a wheel it drives the rotation. In stage pyrotechnics, T1 and T2 gerbs fire 1 to 8 m with very little incandescent fallout. They are fired singly to mark an accent, in a line for a curtain, in crossing pairs for a weave, or in a fast sequence to run along a stage or a bridge.
In practice, for the display company
A gerb is the effect most sensitive to synchronisation, because its jet starts and stops cleanly: a chase line of gerbs needs one cue per piece and delays to the tenth. PyroDesk chains those cues in the timeline, and PyroSimulator checks the visual run; the height and duration entered feed the safety distance on the site plan.