Vacuum System is responsible for generating the suction required to operate the vacuum flight instruments (horizon, directional gyro, turn coordinator ...) The vacuum can be generated by a vacuum pump coupled to the engine or by a Venturi. The Venturi is installed on the exterior of the aircraft and aligned with the longitudinal axis. To circulate air through the venturi creates a suction pressure that the instruments connected to suction drum spinning internal gyro. You must install a vacuum regulator and an air filter for proper operation of the vacuum system. The vacuum gauge is useful to verify that the whole system works correctly.