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.
The length of Sudan's borders is 6,751 kilometers. Border countries are: 1  Central African Republic (175 km). 2  Chad (1,360 km). 3  Egypt (1,275 km). 4  Eritrea (605 km). 5  Ethiopia (769 km). 6  Libya (383 km).