The pneumatic system should be purged periodically  to remove the contamination, moisture, or oil from the  components and lines. Purging the system is accomplished  by pressurizing it and removing the plumbing from  various components throughout the system. Removal of  the pressurized lines causes a high rate of airflow through  the system, causing foreign matter to be exhausted from  the system. If an excessive amount of foreign matter,  particularly oil, is exhausted from any one system, the lines  and components should be removed and cleaned or replaced. Upon completion of pneumatic system purging and after  reconnecting all the system components, the system air  bottles should be drained to exhaust any moisture or  impurities that may have accumulated there. After draining the air bottles, service the system with nitrogen  or clean, dry compressed air. The system should then be  given a thorough operational check and an inspection for  leaks and security. 12-53