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 borders by Egypt to the north, the Red Sea to the northeast, Eritrea and Ethiopia to the east, South Sudan to the south, the Central African Republic to the southwest, Chad to the west, and Libya to the northwest. Sudan used to have the largest area of all the countries in Africa. However, on July 9, 2011, the southern part of the country left and became a new country, South Sudan. Sudan now has an area of 1,861,484 km2, and is the third largest country in Africa by area. The Nile flows through Sudan, providing water to crops.