What is the function of the storage tank of a thermal oil heater?

Functions and precautions of the storage tank of a thermal oil heater:

The storage tank is used to store the heat medium oil of the heating system;
The storage tank is used to receive the overrunning heat medium oil;
The storage tank is used to supplement heat medium oil for the heating system;
The storage tank should be placed at the lowest position of the system;
A firewall should be placed between the storage tank and the thermal oil heater;
The storage tank should be operated at a low liquid level.