What does the little red button on the handle of a traditional pressure cooker that jumps up mean?

That's the pressure cooker's air vent. On either side of the handle are air vents, which expel air first when the pressure cooker heats up.

The lid and body of a pressure cooker snap together. There is a gas outlet hole in the center of the lid, and the hole is covered with a pressure limiting valve, when the gas pressure in the pot reaches a limited value, the pressure limiting valve is pushed up by the pot to release some of the gas, which realizes the control of the pressure of the gas in the pot. So you can see the pressure cooker in the cooking things, the pressure limiting valve in the nuisance of gas, is in the control of the pot gas pressure.

Safety valve is used for emergency exhaust, safety valve in the middle of a layer of aluminum tin material metal, when the pot is too much air pressure, high temperature. Aluminum tin sheet will melt in order to achieve the role of emergency safety exhaust.

Extended information

Pressure cooker explosion is usually caused by improper use.

If these two holes are plugged and the cooker continues to heat up and the pressure keeps rising, then the cooker will not be able to withstand it and cause an explosion. This is why most pressure cookers explode.

Some people cook green beans, green beans blossom, bean skin blocking air holes, pressure cooker will explode. Or when stewing meat, meat put too much will also block the air holes, resulting in pressure cooker explosion.