In a sealed or recovery cooling system the recovery radiator cap (double seal) allows coolant to flow to and from the recovery or expansion tank, maintaining
the integrity of the cooling system. In a correctly operational recovery cooling system, coolant checks are only required at OEM recommended service intervals as the coolant is maintained within the system.
The radiator cap is designed to seal the cooling system to prevent coolant loss, maintain pressure within the cooling system and raise the boiling point of the coolant. Radiator caps are manufactured to a predetermined pressure rating, utilising either metal or plastic design.