sentences:  In Europe the design and the construction of expansion tanks are ruled by EN 13831 according to Pressure Equipment Directive (PED) 97/23/EC.An expansion tank, also known as "overflow bottle", is also used in the cooling system of most internal combustion engines, to allow the coolant, the antifreeze, and the air in the system to expand with rising temperature and pressure.The tank is also called a "coolant recovery tank", since it prevents venting and permanent loss of coolant, by allowing it to be sucked back into the cooling system as the engine cools.