The throttle device is a throttle device that flows through the pipe filled with fluid, the beam will form a local contraction at the throttle, so that the flow rate increases, the static pressure decreases, so that the pressure difference is generated before and after the throttle, the throttle device drains the installation of differential pressure transmitter or multi-parameter transmitter, the faster the flow rate, the greater the pressure difference, The size of the flow is proportional to the differential pressure square root, the throttle flow meter application range is particularly extensive, in the flow measurement of closed pipes have a variety of objects have applications, such as fluid: single phase, mixed phase, clean, dirty, viscous flow, etc. ; From a few mm to a few m; Its usage in various industrial sectors accounts for about 1/41/3 of the total amount of the flow meter.