At what psi is the safety valve in an air brake system set to relieve pressure?

At what psi is the safety valve in an air brake system set to relieve pressure?

• A. 100 psi
• B. 150 psi
• C. 120 psi
• D. 200 psi

Answer: (B)

The safety relief valve in an air brake system is designed to prevent over-pressurization by venting air when pressure reaches about 150 psi. In normal operation, the governor keeps system pressure cycling between roughly 100 psi (cut-in) and about 125 psi (cut-out). The safety valve stays closed during regular use, but if pressure climbs toward the maximum safe limit, it opens to vent air and protect components from damage. So, the standard setting to relieve pressure is about 150 psi, ensuring the system has a safety margin beyond normal operating ranges. Choices much lower than that would fail to protect against over-pressurization, and a much higher setting would risk exceeding safe pressures for the system.

The safety relief valve in an air brake system is designed to prevent over-pressurization by venting air when pressure reaches about 150 psi. In normal operation, the governor keeps system pressure cycling between roughly 100 psi (cut-in) and about 125 psi (cut-out). The safety valve stays closed during regular use, but if pressure climbs toward the maximum safe limit, it opens to vent air and protect components from damage. So, the standard setting to relieve pressure is about 150 psi, ensuring the system has a safety margin beyond normal operating ranges. Choices much lower than that would fail to protect against over-pressurization, and a much higher setting would risk exceeding safe pressures for the system.