Pipe flowmeter measurement method
Ultrasonic waves carry information about the fluid flow rate as they propagate through the flowing fluid. Therefore, the flow rate of the fluid can be detected by the received ultrasonic wave, and converted into a flow rate. According to the detection method, it can be divided into different types of ultrasonic flowmeters such as propagation velocity difference method, Doppler method, beam offset method, noise method and correlation method. Ultrasonic flowmeter is a kind of application that has been applied since the rapid development of integrated circuit technology in the past decade.
Non-contact instrument for measuring fluids that are difficult to access and observe, as well as large pipe runoff. It is linked to a water level gauge for flow measurement of open water flow. The use of ultrasonic flow rate does not change the flow state of the fluid without installing the measuring element in the fluid, and does not generate additional resistance. The installation and maintenance of the instrument can not affect the operation of the production pipeline and is an ideal energy-saving flowmeter.
As we all know, industrial flow measurement generally has the problem of large diameter and large flow measurement difficulty. This is because the general flowmeter will bring difficulties in manufacturing and transportation with the increase of the measuring pipe diameter, and the cost will increase and the energy loss will increase. Installation is not only a disadvantage, but ultrasonic flowmeters can be avoided.
The structure of the electromagnetic flowmeter is mainly composed of a magnetic circuit system, a measuring conduit, an electrode, a casing, a lining, and a converter.
Magnetic circuit system: its role is to produce a uniform DC or AC magnetic field. The DC magnetic circuit is realized by a permanent magnet, which has the advantages of simple structure and less interference by the alternating magnetic field, but it is easy to polarize the electrolyte liquid in the measuring duct, so that the positive electrode is surrounded by negative ions, and the negative electrode is positive ion Surrounding, that is, the polarization phenomenon of the electrode, and causing an increase in internal resistance between the two electrodes, thus seriously affecting the normal operation of the meter. When the diameter of the pipe is large, the permanent magnets are correspondingly large, bulky and uneconomical, so the electromagnetic flowmeter generally adopts an alternating magnetic field and is generated by the excitation of a 50HZ power frequency power source.
Measuring catheter: its function is to let the conductive liquid to be tested pass. In order to make the magnetic flux diverted or short-circuited when the magnetic flux passes through the measuring catheter, the measuring catheter must be made of non-magnetic, low electrical conductivity, low thermal conductivity and mechanical strength. Non-magnetic stainless steel, FRP, high strength can be used. Plastic, aluminum, etc.
1. Requirements for straight pipe sections
Inlet/outlet straight pipe section: inlet should be ≥10×DN; outlet should be ≥5×DN
2. Grounding point requirement
In order to make the instrument work reliably, improve the measurement accuracy, free from external parasitic potential / the sensor should have good grounding, the grounding resistance is less than 10. (If the metal pipe is well grounded, no special grounding device is required) 3.3 Pair installation Location requirements as shown
Insert the electromagnetic flowmeter according to the situation of the pipeline in the field. If the flowmeter without the ball valve is installed, it should be installed on the pipeline without overpressure (that is, the flowmeter without the ball valve can be installed without pressure), and the hole is opened in the pipeline. Diameter 50, ready to weld the connecting welded pipe to the opening of the pipe; for occasions requiring constant flow loading or unloading or no media spillage, a ball valve must be installed, that is, a plug-in electromagnetic flowmeter with a ball valve structure is selected; With a diameter of 50, it is ready to weld the connecting welded pipe to the opening of the pipe.
Measuring range : Recommended range: 0.5m/s to 10m/s continuously adjustable. Maximum use range: continuously adjustable from 0.2m/s to 15m/s
Signal output: 1, the switch quantity can be set to: pulse output (up to 1000HZ); high/low flow alarm; empty pipe alarm; flow direction indication;
Fault alarm; 2, current output: 4-20mA output
Configuration method: 1. Field configuration through three manual keys. 2. Field configuration via remote control. 3. Perform on-site configuration through the handheld communicator.
Memory: The memory that the EEPROM does not disappear, no battery saving.