Manitoba Airbrake Practice Exam

The safety valve is designed to open when the air pressure in a system reaches a certain level to prevent any excess pressure from building up and causing damage. In this scenario, options A, B, and D all have lower pressure levels than C, meaning the safety valve would not open until the pressure reaches 150 PSI. This could potentially lead to an unsafe build-up of pressure before the valve opens. Option C, 150 PSI, is the correct answer as it is the highest pressure level listed and is most likely to trigger the safety valve to open at a safe level.