A product purpose and scope of 
 1.1 Features 
 In the production process of the petroleum, chemical, metallurgy, electric power, light industry, textile, scientific research, military, and other industries, is still a lot of use of various types of throttling device for measurement, control and regulation of fluid flow. In recent years, electromagnetic flowmeters, vortex flowmeters new instruments, but because of the throttling device has a simple structure, solid, reliable, stable performance, accuracy is moderate, low-cost advantages, making its usage still an absolute advantage. Throttling device supporting instruments - differential pressure transmitter will be the throttling device differential pressure into the current standard signal (~ 20mAD.C), the differential pressure transmitter of specifications, variety is very rich, can be adapted to each class of user needs. Is made of emerging smart differential pressure transmitter with the throttle device integration has brought great convenience and efficiency, not only to the installation, the user need not be laid to install pipelines, and can achieve temperature, pressure automatic compensation, fault diagnosis, the range is very wide field range adjustment, with the host computer and communications functions, and more to expand the scope of the throttling device. 
 Throttling device includes a standard orifice standard nozzle diameter nozzle, classical Venturi tube Venturi nozzle, a circular orifice, the fourth round nozzle (fourth hole board), tapered inlet orifice, circular orifice, eccentric orifice, double orifice, low pressure loss flow tubes, rectangular Venturi tube, V-cone flowmeter, wedge flow meter, built-in orifice plate, orifice plate, when the fluid Reynolds number lower or contain impurities, the choice of non-standard throttling device. 
 1.2 throttling device should meet the following fluid conditions 
 1.2.1 The fluid must be filled with pipes, and the flow is continuous. 
 1.2.2 The fluid must be Newtonian fluid (such as ordinary water, acid, alkali solution, superheated steam, all kinds of gases, dry saturated steam), the fluid near the throttling device should not occur phase change (from liquid to change gaseous or vice versa ); fluid should be single-phase (gas or liquid) or can be viewed as single-phase [for example, the gas stream does not exceed 2% (mass components) dispersed solid particles in the fluid flow does not exceed 5% (volume composition) dispersed bubbles. 
 1.2.3 The fluid flows through the throttling device before the jet must be parallel to the pipe axis, not a rotating flow or eccentric flow, not pulsatile flow or critical flow. 
 2 works with structure and parameters 
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