1. 8596. Which statement regarding an aircraft instrument vacuum system is true? A. Dry-type vacuum pumps with carbon vanes are very susceptible to damage from solid airborne particles and must take in only filtered air. B. Vacuum systems are generally more effective at high altitudes than positive pressure systems. C. If the air inlet to each vacuum instrument is connected to a common atmospheric pressure manifold, the system generally will be equipped with individual instrument filters only.