Radiator Pressure Caps - Products - Aashirvad Auto Tech (Guj.) P. Ltd.

When the engine is started from cold conditions the temperature of coolant rises due to heating up the engine. Heat extracts from engine water jacket. As the temperature rises, the volume of coolant is expanding and positive pressure starts to take up. This goes on up to certain extent, which is prevented to avoid damages to the cooling system.

As the pressure exceeds , the set limit of system , pressure cap starts functioning and lower sealing discs is lifted releasing pressure and allowing the hot coolant to escape through the overflow tube provided in the fillerneck . If single sealing cap is there and no reservoir is in the system, then the coolant will be lost . However , if double sealing cap is there and the recovery reservoir is provided in the cooling system , then coolant escaped from overflow tube is collected in recovery reservoir and cooled down the temperature.

When the radiator is cooled, coolant inlet temperature reaches below boiling temperature , it contracts and the pressure inside the radiator reduces and reaches to negative pressure i.e vacuum is not broken , it damages the radiator and its hoses in extreme cases . The vacuum valve provided in the cap comes in operation and allows Air to enter into the radiator via overflow tube of fillerneck in case of single sealing , and coolant from recovery reservoir in case of double sealing and breaks the vacuum in the cooling system.