What is the purpose of the safety (relief) valve on an air brake system's wet tank?

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1. It signals the compressor to shut off permanently
2. It lets the driver manually release all air from the tanks for cleaning, a maintenance step done once a year
3. It warms the air before it reaches the brake chambers
4. It releases air automatically if tank pressure rises dangerously high, protecting the system from over-pressurization

Correct!

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