The HDF category(including the 300,500,600 and 800 series)ultrasonic flowmeters is based on the principle of speed difference and is used to measure the flow of a liquid in a round pipe.Meters of this category feature an advanced design technology relating to micro power dissipation featuring digitalization such as digital transmission,receipt,analysis,output,ete.The meter features accurate measurement and reliable operation,making it more suitable for needs of industrial sites.The product manufacture standard is CJ/T3063-1997 and calibration code is JJG198-1994