A HIGH ACCURACY, PORTABLE CALIBRATION STANDARD FOR LOW MASS FLOW

The devices used to control and measure low mass flows of gases in many critical industrial processes must be calibrated regularly. The systems traditionally used for calibration have low response time, limited performance at very low flow and are not readily portable. A mass flow calibration system has been developed to provide an easy to use, compact and rugged, high accuracy calibration source. It is founded on well established laminar flow theory and the known thermodynamic properties of gases. A new design of laminar flow element combined with today's modern materials, sensor, mathematical modeling and data processing technologies results in new levels of performance for laminar flow element based measurements. The system is calibrated using a gravimetric technique and a complete uncertainty analysis has been performed. Over the past several years, numerous intercomparisons with other standards have been made.