Introduction: The Significance of Fluids in Everyday Life
There are various fluids such as air, water, and gas around us. These fluids are closely related to people's daily life and social activities. The blood in the human body is circulating; the air around us is flowing; the daily life requires the supply of tap water and gas; the used water is discharged through the sewer and so on. For a running car, there are many kinds of fluids, such as gasoline as fuel, air to help gasoline burn, lubricating oil for engine, and exhaust gas. These fluids are closely related to people.
Fluid Flow Measurement: Necessity and Diverse Fields
When we work with various fluids, we often need to understand the properties and quantities or total value of these fluids. In most occasions, it is necessary to know the flow rate of the fluid, so the flow rate of the fluid under various flow states must be measured in various fields. For example, blood flow needs to be measured in order to study how changes in blood flow affect the functioning of the human body. In order to collect gas and water bills, it is necessary to measure the consumption of gas and tap water. From a management point of view, gas companies and water plants all need to measure gas and water totalized flow, and wastewater treatment plants also need to measure the sewage flow rate
for management. In order to measure the substances that pollute the atmosphere in automobile exhaust, it is necessary to measure the exhaust gas flow. At present, in order to further reduce the pollutants in the exhaust gas and save the consumption of gasoline, it is necessary to adjust the ratio of air to fuel of the engine. Therefore, the flow of air and fuel must be measured. From other production fields, the flow measurement of various fluids is also very important, and the flow measurement of various fluids must also be carried out in the management of production processes or in fluid transportation and business transactions.
Evolving Technological Landscape: Complex Fluid Measurement Demands
Recently, industrial technology has developed rapidly, requiring higher accuracy in flow measurement and diversification of the fluids to be measured. For example, the measurement fluids include gas, liquid, and mixed fluid, and the measurement conditions include a temperature range from high temperature flow meter to extremely low temperature (cryogenic flow meter, Liquid nitrogen flow meter.,etc ), and a pressure range from high pressure to low pressure. In addition, there are low-viscosity liquids (such as petro, diesel, alcohol flow meter) and very high-viscosity liquids ( such as butter flowmeter, asphalt flow meter, resin flow meter, honey flow meter
), and it is also required to be able to measure the flow rate from a small flow rate ( micro flow meter) to a large flow rate. The flow under various flow states such as laminar flow, case flow, pulsating flow, and miscible flow has become the measurement object. The current flow measurement is extremely complex and diverse, and it is impossible to measure all the flow with one flow measurement method.
Multitude of Flow Measurement Challenges and Solutions
There are different classification methods for flowmeters. There are more than 100 kinds of flowmeters in use at present. The measurement principles, measurement methods and structures have their own characteristics and features, and the measurement operations and use methods are also different. Therefore, when measuring the fluids flow, it is necessary to fully study the measurement conditions in advance, and select a flowmeter with a measurement method suitable for these conditions. In addition, the instruments technician must fully understand the various flow measurement methods and the features of the flowmeter.
Ensuring Accurate Flow Measurement: Factors and Precautions
When measuring flow rate and totalized total flow, if you just install a flowmeter
and read the measured value, you may not be able to obtain an accurate flow. Some flowmeters have different characteristics due to the different installation methods and the state of the pipelines before and after the flowmeter, and the flow state is affected flow measurement value. In order to measure the flow accurately, it is necessary not only to know the relevant knowledge of the flowmeter itself, but also to know the relevant precautions of the entire measurement system including the flowmeter. For example: as a general common knowledge when measuring the flow rate: the inflow part of the flowmeter should be rectified; in the case of liquid flow measurement, air bubbles should not be mixed. For this reason, it is often necessary to install a rectification device and a degassing device upstream of the flowmeter before measurement can be performed. In addition, when using the flowmeter device, there is a possibility that performance changes and failures may occur due to friction, corrosion, or the influence of adhered substances such as floating solids or particles in the fluid. So take action on it. Regular maintenance management is also extremely important for reliable flow measurement.There is also such a flowmeter: if the physical properties of the fluid to be measured, such as density, viscosity, compression ratio, heat capacity ratio, etc., are not obtained, it cannot measure the flow rate of the fluid. Therefore, it is sometimes necessary to know the method of measuring or obtaining the physical property values of these fluids.
Fluid Properties and Calibration: Calibration for Precision
The calibration of the flowmeter is also an important work for accurate flow measurement. As the fluid flows through the flowmeter, its flow is measured with a standard flowmeter (master flow meter) and a calibration device to calibrate the flowmeter. This method is widely used. During the use of the instrument, this calibration work needs to be carried out every appropriate period.
Holistic Approach: Beyond Flowmeters
In order to perform reliable flow measurement, it is of course necessary to master the knowledge of the flowmeter, but also pay attention to the accessories instrument and consider the entire assembly system. Especially in recent years, there has been great progress in flow measurement technology. New flow meters have been used one after another, and the flow that was difficult to measure in the past can now be measured. In addition, with the improvement of the accuracy of flow measurement, a new field of flow measurement has been opened up, a lot of digital flow meters
with pulse,4-20Ma or RS485, HART ,Profibus-DP are available now; at about the same time, with the development of electronic technology, the flow measurement method has been improved, the mass flow measuremen
t method has been adopted, etc., the flow measurement has recently developed amazingly . Therefore, a systematic summary of the data related to flow measurement (including the latest new data on flow measurement) will play a great role in the flow measurement work.