的安装注意事项 Installation precautions for orifice flowmeters
1. The gas take-out port is preferably in the upper part of the pipe; the liquid take-out port is below the side but not directly below, and the sediment particles will block the take-out port; if it is steam, the take-out port is on the side of the pipe; 2. the direction of the orifice plate is not required Make a mistake. The ones marked "+" are positive, "-" are negative, and "+" is the direction in which the fluid is coming. 3. The pressure guiding tubes leading from the positive and negative pressure taking ports must be parallel in any case; 4. The orifice plate should generally be used with a differential pressure transmitter. Pay attention to the positive pressure when connecting the pressure guiding tube to the differential pressure transmitter. Negative pressure should not be reversed, "H" is positive, "L" is negative; 5. When measuring gas, the differential pressure device is recommended to be placed above the pipeline, and liquid is to be placed below the pipeline. If steam is equipped with a condensation tank, it should be Keep the condensation tank at the same level. 6. Straight pipe section is required. According to the calculation book, calculate the length of the straight pipe section required before and after installing the orifice plate, usually the first 20D and then 10D (D refers to the orifice plate diameter). Throttling device V cone flowmeter and orifice plate Flowmeter performance comparison: V-cone flowmeter (also known as inner cone, V-cone, V-cone flowmeter) is a new generation of differential pressure flowmeter measuring instrument. The transmitter and the secondary instrument are matched. The conical tube is a patented technical product. It has made great technical improvements to the old differential pressure device. It consists of a circular measuring tube and a special core that is placed in the measuring tube and coaxial with the measuring tube. The core and the cylindrical surface inside the measuring tube form a different-diameter ring-shaped overflow crack, which restricts the flow of the fluid. Its throttling history is similar to the throttling history of the annular orifice plate and the classic venturi tube. The special structure of the conical tube effectively eliminates the performance problems of the orifice plates and nozzles currently in use, making it not permanently abraded and contaminated by the sharp edges of throttle parts such as orifice plates during the application process, and can The velocity dispersion gradient of the fluid in the pipe before the flow and various non-axisymmetric velocity dispersions that are probably permanent for additional effective flow resolution (rectification), so that high-accuracy and high-level flow measurement can be achieved. The conical tube flowmeter can be used for the measurement of various liquids, gases and vapors. It is a dream replacement product of the old throttling meter such as the size orifice plate. It provides an effective, Reliable metering wrist.
与V锥形流量计技能性能特性 Orifice flowmeter and V-cone flowmeter technical performance characteristics
The V-cone flowmeter has a complete set of technical characteristics of high accuracy, high reliability and strong compliance (above referred to as double high and strong), which is suitable for the performance of the best contemporary measuring instruments. High accuracy: Outflow coefficient is not absolute ± 0.5% (range ratio 10: 1) Outflow coefficient is not absolute ± 0.3% (range ratio 4: 1) High reliability: simple, robust and long-term differential pressure device structure Durable, and good anti-blocking, the skills of supporting differential pressure transmitters are sophisticated, level and reliable. Product wins are applied to industries, energy industries, and various measurement sites. All of them have outstanding operating forms, measurement performance is chaotic, and the stagnation rate due to product leakage is zero. Strong compliance: Conical flowmeter products have strong compliance with measurement conditions, which is beyond the reach of other general flowmeters. This is also one of the first reasons why conical tube products can maintain high accuracy and reliability in the application process. The detailed list is as follows today: (1) Strong compliance with the nature, working conditions and on-site environmental conditions of the fluid being measured. It can not only measure clean ordinary fluids with high accuracy, but also measure high-viscosity fluids, high-moisture gases, Fluid containing solid particles and other dirty fluids, and can adapt to high-temperature, high-pressure, low-temperature, low-pressure working conditions and strong shocks and other harsh environmental conditions. (2) The scale of the suitable Reynolds number is wide, the upper limit of the Reynolds number is uncontrolled, and the lower limit can be very low. Therefore, it can measure both high flow velocity and low flow rate, and low Reynolds number flow rate. Junyi is the lower limit of its measurable flow rate. Value is much lower than the flowmeters such as precession vortex and vortex street. (3) Wide range ratio: more than 10: 1, which can fully meet the requirements of ordinary industry and energy measurement. (4) Begging low for the straight pipe section in front of the meter inlet, only 3D, far lower than orifice plates, nozzles and other speed-type flow meters such as vortex streets and turbines.
3.A brief analysis of product performance mechanism
Why can V-cone flowmeters have such excellent technical performance? The most basic reason is the simple and scientifically reasonable structure and the throttling mode caused by it. It should be said that the conical tube is a re-development of the skills of the annular orifice plate and the classic venturi tube. It combines the performance and characteristics of the annular orifice plate, the classic venturi tube, the wear-resistant orifice plate, and the conical inlet orifice plate. Eliminates the measurement performance problems of the orifice plate, making it a new type of throttling flow measurement instrument with complete "selective genetic hybridization" characteristics. The primary measurement performance problems of the size orifice plate: ① During the application process, the sharp edges of the outbreak throttle restrictor are abraded and contaminated, which causes the outflow coefficient to change slowly, resulting in a difficult flow measurement difference. ② In the middle and low Reynolds number measurement area, the outflow coefficient changes greatly with the change of flow conditions, resulting in a compiled measurement difference pool. ③ The excessively high requirements for the installation of straight pipe sections and the severe demands of the orifice plate installation are difficult to meet the standards, which often results in a large additional installation difference, which is often difficult to quantitatively evaluate. ④ Large pressure loss
形式上风：(1)有充足的实验数据表明，它对消除来自上游的流动扰攘所造成的非轴对称性速度散播的才能极强，对入口的直管段哀求低。 The orifice plate flowmeter has the advantages : (1) There is sufficient experimental data to show that it is very strong at eliminating the non-axisymmetric velocity dispersal caused by the flow disturbance from the upstream, and begging for a low straight inlet section. (2) The fouling of the throttling parts is not permanent, and the mixed-phase flow can be measured.
The classic Venturi tube has the advantages of metering performance: (1) Low requirements for the straight pipe section of the inlet. (2) Fouling is small and pressure loss is small. (3) Mixed phase flow can be measured. The metering performance of the wear-resistant orifice plate and the conical inlet orifice plate is advantageous: (1) there is no sharp edge abrasion, and the outflow coefficient is relatively flat and chaotic. (2) A small Reynolds number can also be measured with a conical inlet orifice.