The expansion tank serves to fill the system with coolant, with a volume that ensures the preservation of the liquid expanding with increasing temperature and the connection of the cooling system with the environment when the pressure in the cooling system rises or falls. In its design, it can be either removable or non-removable, made together with the radiator.
The opening pressure of the overpressure valve in the cap of the expansion tank is 1.10–0.80 kgf / cm2. The opening vacuum of the vacuum valve in the plug of the expansion tank is 0.1 kgf/cm2.