An ISO Tank is a tank container which is built to the ISO standard (International Organisation for Standardisation). ISO tanks are designed to carry hazardous liquids in bulk.The tank is made of stainless steel and is surrounded by various types of protective layers. Different skins can be used with an ISO tank depending on the type of bulk cargo it is carrying. It has a manhole on the top along with at least one valve and another valve on the bottom. They are shaped like a cylinder.Because ISO tanks are built to the ISO standard, the frame which the tank sits in measures about 6 metres long, 2.4 metres wide and between 2.4-2.5 metres high. The tanks vary in size and type and can carry between 21,000 and 40,000 litres of liquid.