The purpose of an air gap is not really to allow air to escape but rather to keep dirty water from back flowing into the DW. An autovent allows air into the system to allow for proper drainage and an air gap is not dependant on one or vice versa. The autovent takes the place of a vent stack to the roof.
Sudan is a member of the United Nations, the African Union, the Arab League, the Organisation of Islamic Cooperation and the Non-Aligned Movement, as well as an observer in the World Trade Organization. Its capital is Khartoum, the political, cultural and commercial centre of the nation.
Sudan is often referred to as North Sudan as South Sudan seceded in 2011 with the consent of Sudan. The last official census recording the population of Sudan included the populations of Eastern, Western and Northern Sudan in 2008 and recorded over 30 million citizens, which puts present estimates of the population of Sudan post-secession at 41.51 million.