差压式流量计 ． Throttling flowmeter is a typical differential pressure flowmeter . 、 气体和蒸气流量的最常用的一种流量仪表 ． It is the most commonly used flow meter for measuring liquid , gas and vapor flow in industrial production . 是 节流式流量计的主要优点。 Easy to use, simple structure and long life are the main advantages of throttling flowmeter. 这大大提高的工作的效率， 这是其它流量计难以具备的 ，所以它的使用非常广泛，备受工厂的青睐。 The standard throttling device is designed and manufactured according to the technical standards prescribed by the country, and can be applied without calibration. This greatly improves the efficiency of work. This is difficult for other flowmeters to use, so it is widely used and favored by factories. 它的适用性广，对各种工况下的单相流体、管径在 50 ～ 1000mm 范围内都可使用。 In addition, it has wide applicability, and can be used for single-phase fluids and tube diameters in the range of 50 to 1000 mm under various working conditions . 还有一些需要注意的问题。 The disadvantage is that the range is relatively narrow, and there are some issues that need attention.
要有专业的基础知识。 The pressure loss of the throttling device is large and requires a certain amount of power; strict requirements for installation require professional basic knowledge. 需要足够长的直管段。 Installation requires a long enough straight pipe section. Despite this, it is still the most widely used flow measurement instrument.
常用节流装置是孔板，其次是喷嘴，文丘里管应用要少一些，应针对具体情况的不同，首先要尽可能选择标准节流装置， 万 不得已才选择特殊节流装置。 At present, the most commonly used throttling devices are orifice plates, followed by nozzles. Venturi tubes are less commonly used. Depending on the specific situation, firstly select the standard throttling device as much as possible, and choose a special throttling device. From the perspective of use, the main points for the selection of the throttling device should consider the following aspects:
Throttle device allows pressure loss. 50 ％～ 90 ％，喷嘴也可达 30 ％～ 80 ％，文丘里管可达 10 ％～ 20 ％。 The pressure loss of the orifice plate is large, which can reach 50 % to 90 % of the maximum pressure difference , the nozzle can also reach 30 % to 80 %, and the Venturi tube can reach 10 % to 20 %. The type of throttling device is selected according to the pipeline transportation pressure and the allowable pressure loss on the production pipeline. If the pressure loss permits, the orifice plate should be considered first.
The difficulty of processing the throttling device. 当然 造价也是文丘里最高，故一般情况下选用孔板。 In terms of ease of processing and assembly, orifice plates are the simplest, nozzles are second, and Venturi is the most complicated. Of course, the cost is also the highest in Venturi, so in general, orifice plates are used.