是一种使用简单、读数方便、用途十分广泛的瞬时流量测量仪表。 The glass rotor flowmeter is a kind of instantaneous flow measuring instrument which is simple to use, convenient to read and very versatile. In the field of environmental protection equipment and instruments, the amount is more than 30,000 units / year. Therefore, it is extremely important to choose and use this instrument.
I. Variety and selection of glass to flowmeter
The glass rotor flowmeter can be divided into eight types: ordinary type, ribbed vascular type, micro flow and small outline type, corrosion resistance, laboratory type, thermal insulation type, alarm type and high pressure resistance type according to its use and applicable range. series. According to the instrument series spectrum developed by the country, no matter which series includes a maximum of 12 calibers from 1mm to 100mm, the measurable flow range is: liquid (water) 0.1ml / min ～ 40m3 / hour, gas (Air) 1 ml / min to 1000 cubic meters / hour. The glass rotor flowmeter used for environmental protection instruments generally has a diameter of no more than 10 mm, and the measured flow belongs to a small flow range.
The selection of glass rotor flowmeter can be considered from the following aspects.
1. The object of measurement. That is to measure the type of medium, pressure, and chemical properties. For liquid and gaseous media, for corrosive media, a corrosion-resistant flowmeter should be selected. 2. The performance of the flow meter itself. After the above conditions are determined, generally speaking, if there is no major change in price, the needle valve is preferred to be placed on the upper part of the flowmeter; those with larger flow holes are directly flow-scaled; simple structures; smaller external dimensions, etc . If it is a small flow range, you can use the ball float type, because it is stable during measurement, not easy to accumulate dust, high accuracy, and good interchangeability. 3． Select based on price. Generally speaking, high accuracy and high price. To select the accuracy level of the instrument according to the measurement purpose, if you only need to control the throughput of the measurement medium and adjust it after trial operation, you must always stabilize the throughput in the future, then the accuracy is secondary.
的刻度修正 Calibration of glass rotor flowmeter
The calibration of the glass rotor flowmeter is obtained by the factory under the conditions of the factory using water and dry air close to the ideal fluid as the medium. However, there are two situations where the scale value of the flowmeter cannot be used directly: one is that the measurement medium is not water and air, and the other is that the medium is water and air, but its state (temperature, pressure) and scale The status is different. In this way, when using a flow meter, in order to obtain a correct measurement result, a problem arises that the scale value needs to be corrected. Therefore, solving the calibration of the glass rotor flowmeter is the key to using this instrument. Considering that environmental protection instruments use rotor flowmeters to measure the flow of gaseous media, only the density correction in gaseous media measurement is discussed below. Because the viscosity of the gaseous medium is small, the viscosity effect is omitted in the discussion. Practice has proved that this does not affect the accuracy after the correction. The glass tube rotor flowmeter has a simple structure and a glass tube rotor flowmeter. It is easy to use and has the disadvantage of low pressure resistance and a greater risk of fragility of the glass tube; suitable for small diameters and low flow rates; low pressure loss. Also known as fixed displacement flowmeter, referred to as PD flowmeter, the flow meter is the highest accuracy type. The mechanical measuring element is used to continuously and continuously divide the fluid into a single known volume part, and the total volume of the fluid is measured according to the number of times the measuring chamber is repeatedly filled and discharged. Can be divided into elliptical gear flowmeter, scraper flowmeter, double rotor flowmeter, rotary piston flowmeter, reciprocating piston flowmeter, disc flowmeter, liquid-sealed drum flowmeter, wet gas meter and membrane gas meter, etc. . Glass tube rotor flowmeters are classified according to their measuring elements. They are often used for total measurement of expensive media (oil, natural gas, etc.). Glass tube rotor flowmeters are ranked as the three most used flowmeters with differential pressure flowmeters and float flowmeters.
工业发达国家近年PD流量计(不包括家用煤气表和家用水表)销售金额占流量仪表的13%~23%;国约占20%.其中椭圆齿轮式和腰轮式分别约占70%和20%。 In 1990, the output (excluding domestic gas meters) was estimated to be 340,000 units. In recent years, the industrial sales of PD pipe flowmeters (excluding domestic gas meters and household water meters) in developed countries of glass tube rotor flow meters accounted for 13% to 23% of flow meters; The country accounts for about 20%. Among them, the oval gear type and the waist wheel type account for about 70% and 20%, respectively. The main type of speed type flowmeter is a glass tube rotor flowmeter. A meter that uses a multi-blade rotor (turbine) to sense the average flow velocity of a fluid, and derive the flow rate or total amount. Can also be made monolithic. Generally, it consists of two parts: a sensor and a display. As one of the ten types of flowmeters, turbine flowmeters and volumetric flowmeters, Coriolis mass flowmeters are called three types of flowmeters with the best repeatability and accuracy. Products. Its products have developed into a multi-variety, multi-series mass production scale. High accuracy, among all flowmeters, it is the most accurate flowmeter; large-caliber meters are mostly used in water supply and drainage projects; small- and medium-caliber meters are often used in high-demand or difficult-to-measure applications, and glass tube rotor flowmeters have a wide range of applications. Air outlet cooling water control, paper industry measures pulp and black liquor, strong corrosive liquid in chemical industry, non-ferrous metallurgy industry's pulp; small and small calibers are often used in places with health requirements such as pharmaceutical industry, food industry, biochemistry. The fluid is alternately separated on both sides of the generator to release two series of regularly staggered vortex meters. The glass tube rotor flowmeter is a non-streamline vortex generator placed in the fluid. According to the frequency detection method, the glass tube rotor flowmeter can be divided into: stress type, strain type, capacitive type, thermal type, vibrating body type, and photoelectric type. And ultrasound. But its rapid development, glass tube rotor flowmeter is the youngest type of flowmeter. It has become a universal type of flowmeter. An ultrasonic flow meter is an instrument that measures the flow by detecting the effect of fluid flow on an ultrasonic beam (or ultrasonic pulse).