With the enterprise to the market, enterprise production and management will be further deepened, the flow measurement is more important, it is not only to improve product quality assurance, but also an important means of improving the economic efficiency of enterprises.
To play the role of the flow meter, in its selection of strict requirements, that is, to determine the measurement method, and then analyse the performance requirements, and then choose a specific instrument. Therefore, automation instrumentation professionals in the premise of a certain degree of professional knowledge, it is necessary to understand the flow measurement instrumentation requirements of the performance, and combined with the specific measurement of the correct choice of instrumentation. Only in this way, to meet the requirements of enterprises, so that the flow measurement to play an important role.
Flow meter is one of the process automation instruments and devices in the large class of instruments, and level measurement instruments occupy the vast majority of chemical production in the field, in the chemical industry, petroleum, transport, food, medicine, agriculture and people's daily lives and other areas of the national economy have played an important role, is the development of industrial and agricultural production, improve product quality, improve economic efficiency and management level of the important means and tools in the national economy occupies an important position. National economy occupies an important position. The more common types of electromagnetic flowmeter, turbine flowmeter and other types of instruments, in the chemical instrumentation device, flow meter has two major functions: as a process automation control system for detecting the instrumentation and measuring the quantity of materials in the total number of tables. It is not only to improve product quality assurance, but also an important means of improving economic efficiency of enterprises, in chemical production plays a vital role.
First of all, the flow meter is to improve product quality assurance. Product quality is the key to survival and development of enterprises, and flow meter measurement results is the basic guarantee of product quality, in the chemical production process, from raw materials into the plant testing and analysis, to the production process in the quality of each process monitoring and control, until the finished product, semi-finished product inspection, must be measured and tested layer by layer, strict control. If there is no flow of testing, supervision and assurance, product quality can not be guaranteed. Because any quality characteristics are characterised by a certain measurement characteristics. Everything to use data to speak, and data must be accurate and reliable, which depends on the perfect measurement and testing equipment to achieve. If the measuring instruments used by the enterprise is not qualified, the product geometry is not qualified, the pressure gauge is not allowed to destroy the equipment. Thus affecting product quality, so product quality must be controlled by precision testing, in order to make the enterprise product quality to reach the advanced level, invincible, it is necessary to strengthen the measurement of detection means, no measurement of detection, there is no product quality.
Secondly, the flow meter is also an important means of improving economic efficiency in the production process. In most industrial enterprises to measure the instrumentation as a way to improve business management, improve product quality, and promote technological progress in the basic work to grasp. Improve the measurement and detection means, strengthen the measurement of management, so that the rational and effective allocation of resources to avoid waste of resources, reduce the consumption of raw materials and energy, improve the economic efficiency of enterprises. There are also some enterprises due to product development and manufacturing management and other aspects of measurement and detection means and production management is not matching, measuring instruments are not fully equipped, inaccurate, so that the manufacturing process out of control, resulting in poor product quality, high consumption, low efficiency.
In view of the importance of measuring instruments, each enterprise in each section of the use of a large number of measuring instruments, they are responsible for measuring a variety of intermediate products, end-products measurement, according to the nature of the product can be divided into many different kinds of measuring instruments, we can choose different types of flow meters according to the actual situation. As many types of flow meters, and selection involves many technical and economic factors. Must be a comprehensive consideration of these factors, it is possible to achieve both technically feasible and economically reasonable.
For a particular use of the occasion, the choice of flowmeter depends on the measurement of the importance of the subject in different aspects (for example: flowmeter in the field under the conditions of the accuracy of the installation, energy costs, installation conditions of the limitations of the special characteristics of the medium to be measured, etc.), therefore, it is necessarily a separate judgement based on engineering and professional knowledge of the matter. In a specific field with similar working conditions, the technical advantages of a certain flowmeter is usually the basis for the initial selection. Obviously, in the specific use of the occasion has not done a detailed understanding of the various constraints, trying to measure, can only be self-righteous assumptions. The following is to help us make the right flow meter, a reasonable selection of the five categories of problems. For the first three categories of problems, only a limited choice, using them to determine whether a flow meter is suitable. After the two categories of problems is difficult, because it involves price and performance comparison and after the decision. The following are the five major categories of problems.
1. Type of fluid to be measured.
2.Working conditions of the process. Instrument selection should not only consider the process, but also according to the temperature and pressure thresholds are determined.
3.Installation conditions of the flowmeter.4.General requirements in terms of flowmeter performance and flow measurement capabilities.
5.Flowmeter installation and operation should be a combination of issues and costs.
All of the above are factors that determine the choice of a particular flowmeter. In comparing the costs of various flowmeters, there are a number of factors that should be taken into account in addition to the actual purchase cost, and the following important factors should be weighed before a decision is made:
Flow meter classification method is also many, there is no uniform classification standard. Usually according to its measurement principle, the flow measurement method is divided into four categories, the use of Bernoulli's equation principle to measure the flow of differential pressure type flow measurement method; the use of measuring the flow rate to get the flow of velocity flow measurement method; the use of a small volume of a standard continuous measurement of the flow of volumetric flow measurement method; in order to measure the quality of fluid quality for the purpose of measuring the quality of the flow measurement method, the use of the principle of electromagnetic induction for the work of the Electromagnetic flowmeter.
Measurement method is determined, the choice of flow instrumentation in the performance requirements need to consider the main factors are: instantaneous flow or measurement of the total amount of accuracy, repeatability, linearity, the upper limit of the flow rate and flow range, range, pressure loss, output signal characteristics and response time. The purpose of measurement of different measurement objects are different, in terms of instrument performance also has its different focus. For example, trade accounting and storage and transport of high accuracy requirements; continuous measurement process control usually only require good reliability and repeatability, and sometimes also require a wide range of degrees, while the measurement of the accuracy requirements of the second; batch ratio production is expected to have good accuracy and so on. Therefore, we are in the measurement method to determine a good, combined with the specific measurement of the object of each performance requirements of the instrument to do item-by-item analysis, on the basis of the correct choice of the required instrumentation.
There are more than 100 kinds of flow meter, but most of them are specific objects of the special flow meter, in the national economy for the general application of the ten categories of general-purpose flow meter, they are:
Hangzhou Economic Development Area，Hangzhou 310018，China
