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.
Test equipment: one 500MΩ insulation resistance tester, one multimeter.
(1) When the pipeline is filled with medium, measure the resistance between terminals A, B and C with a multimeter. The resistance between A-C and B-C should be equal. If the difference is more than 1 time, there may be leakage of the electrode, condensation on the outer wall of the measuring tube or the junction box.
(2) In the case of lining drying, measure the insulation resistance between A-C and B-C with MΩ meter (should be greater than 200MΩ). Then use a multimeter to measure the resistance of the two electrodes in terminals A and B and the measuring tube (should be in short-circuit communication). If the insulation resistance is small, indicating that the electrode is leaking, the entire flowmeter should be returned to the factory for repair. If the insulation is reduced but there is still more than 50 MΩ and the inspection result of step (1) is normal, the outer wall of the measuring tube may be damp, and the inside of the outer casing may be dried by a hot air blower.
(3) Use a multimeter to measure the resistance between X and Y. If it exceeds 200 Ω, the excitation coil and its lead wire may be open or poorly connected. Remove the terminal block check.
(4) Check the insulation resistance between X, Y and C, which should be above 200 MΩ. If it is lowered, dry the inside of the casing with hot air. In actual operation, the decrease in coil insulation will result in increased measurement error and unstable instrument output signal.
(5) If it is determined that the sensor is faulty, please contact the manufacturer of the electromagnetic flowmeter. The general site cannot be solved and needs to be repaired by the manufacturer.
Selection of measurement types for special industrial and commercial users
At present, there are some special users in the supply of industrial and commercial users. On the one hand, the gas points are more dispersed, and the amount of gas used in a single combustion device is small (generally 2 to 9 m3/h); on the other hand, the total amount of gas used is Very large, there are many problems with the accurate measurement of the natural gas supply of such users. This type of industrial and commercial users have multiple fuel appliances with different gas consumption. Different gas consumption at different time periods brings certain difficulties to the accurate measurement of natural gas. Under the condition of satisfying the maximum gas consumption, it cannot be measured under the condition of small flow. The problem.
1. Case 1: A large shopping and entertainment mall
The mall has 22 gas points distributed on the second, fourth and fifth floors. In order to ensure the accuracy of natural gas measurement, the gas supply system has a master meter (turbine flow meter Q650) and 22 sets of compensation functions. As a metering table, the flow meter usually has a gas consumption of about 400m3/d and a holiday of about 800m3/d. It is found through the data collection that the total number of meters and sub-meters is about 17m3 per day; in the initial 54d. The cumulative gas consumption of the master meter and the minute meter differs by 11511.80 m3.