A withdrawal tube (or dip tube) is fitted internally to the valve of a cylinder or drum tank. Withdrawal tubes are used for liquid phase product withdrawal from cylinders of liquefied products such as liquid hydrocarbon blends, carbon dioxide, propane, ammonia or various refrigerants to extract the liquid from the cylinder. The withdrawal tube runs down the centre of the pressurised cylinder and draws the liquid up through the valve. A dual port valve can also be used in combination with a withdrawal tube when additional head space pressurisation is required to remove the liquefied product, or it can allow the product to be withdrawn in either liquid phase with the withdrawal tube or through the vapour port.