When the new air separation plant is purged the first time, the air compressor pressure shall be increased to the quota pressure as far as possible. The purge valve should be fully opened as far as possible. Since the drain valve is connected together, the pressure is different. Therefore, when purging the drain valve, should purge one by one, and then close one after another for half an hour. After purging, do not fully close the purge and drain valves. Shut down the air compressor and wait until there is no pressure. Take all the valve bodies of the purge and discharge valves to check and clean, and then restore them. Only in this way can the purging be qualified.