A fast-burning, heat-producing chemical compound used in rocket motor igniters. When an electrical current heats a bridge wire, the pyrogen coating flashes into a hot flame, which in turn ignites the main solid propellant grain. It ensures a rapid, uniform, and reliable start to the combustion process, preventing hard starts or uneven burning.
Heard on the job
The telemetry showed a failure in the igniter circuit before the pyrogen could even flash.