TU21

The substance shall be protected by a protective agent in the following ways:

Protective agent	A layer of water in the tank	Degree of filling of the substance (including water if any) at a temperature of 60° C shall not exceed	Additional requirements for carriage at low ambient temperatures
Nitrogena	–	96 %	–
Water and nitrogena	–	98 %	The water shall contain sufficient anti- freeze agent to prevent it from freezing. The anti-freeze agent shall be free from corrosive action and not liable to react with the substance.
Water	not less than 12 cm	98 %

a The remaining space of the tank shall be filled with nitrogen in such a way that, even after cooling,

the pressure at no time falls below atmospheric pressure. The tank shall be closed in such a way that

no leakage of gas occurs.