The pilot controls the flame with a blast valve. When he opens the blast valve, the liquid fuel under pressure in the cylinders expand down their fuel hoses. The liquid enters the burner, then proceeds through series of coils located at the base of the flame. Here the liquid is heated from previous ignitions, and changes into a gas. The gas is then sprayed onto the pilot light.
Pilots have the option of bypassing the coils and spraying liquid propane onto the burner.
This produces a less-powerful, less compact yellow flame that results in less heat, but also in less noise. It is useful when flying over livestock that are easily scared. The third, and surely most visible, part of the modern balloon system is the envelope, or balloon. The imagination and the pocketbook is about the only limit. The envelope is made of dozens of individual panels sewn together.