At 30 PSI (205 kPa), the Tridon CL30205 sits at the very top of the pressure range, well beyond the 13 to 18 PSI you'll find on most everyday cars. Some European engines, particularly many BMW models, are designed to run their cooling systems at this much higher pressure, and a cap rated any lower simply won't hold what the system needs.
Why does it matter? Every extra pound of pressure raises the coolant's boiling point by around 1.4°C, so a 30 PSI system has a far bigger buffer against boiling than a conventional one. That's how tightly packaged, hard-working engines stay protected. But it also means the cap is doing a lot of work. Once its seal or spring starts to fatigue, pressure can escape early, and the engine loses that safety margin without any obvious warning.
This plastic screw-on recovery cap is typically found on the coolant expansion tank rather than the radiator itself. Its double-seal design releases coolant into the tank as pressure builds, then allows it to return as the system cools, keeping everything full and air-free. Because the rating is so high, it should only ever be fitted where the manufacturer specifies a 30 PSI cap. Fitting it to a lower-pressure system could overstress hoses, the radiator and the tank.
- Series - CL
- Pressure - 30 (PSI), 205 (kPa)
- System - Recovery
- Cap Style - Plastic
- Connection Type - Plastic Screw
