== EGR vacuum switching valve == Despite the rather lengthy name the EGR-VSV (exhaust gas recirculation vacuum switching valve) does little more than allow vacuum to flow through the system depending on engine coolant temperature.
A double bond in chemistry is a chemical bond between two chemical elements involving four bonding electrons instead of the usual two. The most common double bond, that is between two carbon atoms, can be found in alkenes. Many types of double bonds exist between two different elements. For example, in a carbonyl group with a carbon atom and an oxygen atom. Other common double bonds are found in azo compounds (N=N), imines (C=N) and sulfoxides (S=O).
Definition: A single bond is a chemical link between two atoms in which electrons are shared between them. Examples: There is a single bond between the oxygen and each hydrogen in a water molecule (H 2 O). Each of the covalent bonds contains two electrons-one from a hydrogen atom and one from the oxygen atom.