Lorne here is what one supplier says
KAFTON UK
PRESURE RATING SPEFICATIONS SIZE
13 PSI (0.9 Kg/cm2)
16 PSI (1.1 Kg/cm2) SAE -J-164 (Reaffirmed FEB97) MINI CAP [For 43 mm dia. Filler Neck]
7 PSI (0.5 Kg/cm2)*
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.
About Us
Welcome to Kafton UK. We sell a wide range of Cable ties & Fixings, Releasable Cable Ties, Screw Mounted Cable Ties, Push Mount Cable Ties, Double Loop Cable Ties, Stainless Steel Cable Ties, P Clips and Masonry Mount Screws at very competitive prices. We also have a range of Electrical Terminals and products associated with wiring and connections.
We are continually expanding our product portfolio and now offer a wide range of products. Our continuous focus and efforts is on Service, Quality and Competitiveness. Our products are sourced from manufacturers who are quality conscious and manufacture goods under UL,DIN, UKAS, BSI and RoHS compliance.
