① the reason why the pressure cooker makes food easy to cook: because the evaporated steam stays in the cooker, the air pressure above the liquid surface is increased, the boiling point of water is higher than 1℃, and the food is easy to cook when the temperature is above 1℃;

② Safety devices of pressure cooker: First, safety valve. When the air pressure in the cooker exceeds the specified air pressure value, the air pressure will jack up the safety valve to keep the air pressure in the cooker at a certain value; The second is the fusible sheet, which is made of alloy material with low melting point. Once the safety valve fails and the temperature in the pot reaches the melting point of the fusible sheet, the gas in the pot is ejected from the fusible sheet to prevent explosion accidents.