| 摘要 |
PURPOSE:To accurately measure the mass flow rate of any kind of gas, by measuring the pressure in a container at a predetermined time interval and successively calculating a mass flow rate. CONSTITUTION:A gas entering through an inlet 36 is controlled by a mass flow controller 30 so as to have a constant flow rate and introduced into a container 31 and then made to flow out from an outlet 37 through a valve 33. In measurement, the valve 33 is closed, and the pressure in the container 31 is successively measured by means of a pressure gauge 32 made of stainless steel at a predetermined time interval (e.g., 0.1sec). Since the volumes of the container 31 and the piping of the measuring circuit are previously set in a memory circuit 38, a mass flow rate is calculated by an arithmetic circuit 34 according to the Boyle-Charles' law and displayed on a display 35. According to this momentary flow rate, the mass flow controller 30 is calibrated and corrected. Upon completion of the measurement, the valve 33 is opened. Thus, the mass flow rate of any kind of gas can be accurately measured. |
