When operating the pressure cooker, the safety valve always exhausts automatically. What happened?

The old pressure cooker needs automatic exhaust, and the electric pressure cooker can close the exhaust valve.

Operating steps:

Step 1: Turn the exhaust valve on the pressure cooker cover to the left (or right) position.

Step 2: Cover the pot cover on the pot body, and the gas in the pot will be discharged along the exhaust hole.

Step 3: Turn the pot cover to the locked side to ensure that the pot body is watertight.

Step 4: Align the exhaust valve in the middle of the three directions. At this time, the exhaust valve is locked, and it will not automatically exhaust except for the initial hot air upwelling.