Ullage

Under ullage (English, among other things for " free space ", " filling up tank top " ) is understood in shipping the free space between the surface of a liquid in a tank and the upper end of the tank. Analogously, also the ullage measured value of the vertical distance from the upper top of the tank to the level.

Particulars

In general, one is committed on ships, tanks only completely full or completely empty drive to reduce the stability- reducing effect of free surfaces. However, to give fluids the ability to expand when the temperature rises, filling ship tanks (including tank on land ) only to a certain percentage (eg 98%). With a 100% fill tank otherwise there is a danger that a warming during the trip charge liquid ( oil, gasoline, chemicals ) are so strong stretching that it passes through the tank overflows to the outside ( called overflow ). The remaining space to be selected depends on the expansion of the liquid restrained from ( palm oil a value of about 1.5% is assumed, for example ).

But ullage is not a fixed amount, but also pays off when the tank for various reasons are driven only partly filled. For Direction Finding of the ullage are located on deck tankers referred to as Ullageluken openings.