The Kelvin scale is used to measure absolute temperature, i.e., temperature from absolute zero. The way it is defined, there are no negative temperatures on the Kelvin scale.
Absolute temperature and hence we won't mark degree as we write the temperature. At 4.2 K mercury would loose the resistivity totally and so it becomes super conductor.
The pH scale isn't used for measuring anything. It tells if a substance is an acid or a base. On the pH scale, 7 or more is considered a base. lower than 7, on the pH scale is considered an acid....
The Beaufort scale has been and still is used to describe wind conditions. The max on this scale is 12 which is described as 'hurricane'. However some countries now use an extended scale with numbers...