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

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

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.