Dewar flask is a vacuum insulated stainless steel pressure vessel designed for the storage, transport and use of low temperature liquid CO2. It has excellent adiabatic properties and can maintain a low temperature state of liquid CO2 for a long time to prevent it from vaporizing due to temperature increase. At the same time, it is also equipped with a variety of safety devices, such as safety valves, bursting disks, etc., to ensure that when the pressure in the bottle exceeds the safety limit, it can automatically exhaust pressure relief and prevent the occurrence of safety accidents such as explosions.