Airbag having a stable pressure release device operated with a sphygmomanometer

An airbag having a stable pressure release device operated with a sphygmomanometer, and said sphygmomanometer having an interconnecting pipe, and said interconnecting pipe having a pressurizing device and an air escape valve, and the pressure release of an airflow through an air escape opening of said air escape valve being set according to a standard sized airbag, characterized in that:

• another end of said channel is coupled to a large airbag worn around an arm or a wrist of a user, and said large airbag includes a piston made of a porous material, such that when said sphygmomanometer is used, said pressurizing device pressurizes air and sends the air to said interconnecting pipe to pressurize said large airbag to a predetermined maximum pressure, and when a blood pressure is measured, the air in said airbag passes through said air escape opening of said air escape valve and tiny and even air holes in a piston of said large airbag and through air holes to the outside in a tiny quantity and a steady manner, without the need of adjusting the openness of said air escape opening of said air escape valve to increase the discharged airflow of said large airbag.