A pipe that releases gas to disperse into the atmosphere is called a vent. If the gas is burned at the tip, it is called a flare. In its simplest form, a vent or flare tip is a pipe. Sometimes the pipe diameter is reduced for the last 5 ft or so to increase exit velocity for better mixing with the air. The operating pressure of the vent scrubber can be adjusted by reducing the tip diameter to increase pressure drop across the tip. Fluidic seals also give increased pressure drop and can be used to reduce the infusion of air into the vent piping. There are a variety of vendor-supplied flare tips available with various back-pressures, velocities, and capacities.